test-util-inspect.js

// Flags: --expose-internals
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'use strict';
const common = require('../common');
const assert = require('assert');
const { internalBinding } = require('internal/test/binding');
const JSStream = internalBinding('js_stream').JSStream;
const util = require('util');
const vm = require('vm');
const v8 = require('v8');
const { previewEntries } = internalBinding('util');
const { inspect } = util;
const { MessageChannel } = require('worker_threads');

assert.strictEqual(util.inspect(1), '1');
assert.strictEqual(util.inspect(false), 'false');
assert.strictEqual(util.inspect(''), "''");
assert.strictEqual(util.inspect('hello'), "'hello'");
assert.strictEqual(util.inspect(function abc() {}), '[Function: abc]');
assert.strictEqual(util.inspect(() => {}), '[Function (anonymous)]');
assert.strictEqual(
  util.inspect(async function() {}),
  '[AsyncFunction (anonymous)]'
);
assert.strictEqual(util.inspect(async () => {}), '[AsyncFunction (anonymous)]');

// Special function inspection.
{
  const fn = (() => function*() {})();
  assert.strictEqual(
    util.inspect(fn),
    '[GeneratorFunction (anonymous)]'
  );
  assert.strictEqual(
    util.inspect(async function* abc() {}),
    '[AsyncGeneratorFunction: abc]'
  );
  Object.setPrototypeOf(fn, Object.getPrototypeOf(async () => {}));
  assert.strictEqual(
    util.inspect(fn),
    '[GeneratorFunction (anonymous)] AsyncFunction'
  );
  Object.defineProperty(fn, 'name', { value: 5, configurable: true });
  assert.strictEqual(
    util.inspect(fn),
    '[GeneratorFunction: 5] AsyncFunction'
  );
  Object.defineProperty(fn, Symbol.toStringTag, {
    value: 'Foobar',
    configurable: true
  });
  assert.strictEqual(
    util.inspect({ ['5']: fn }),
    "{ '5': [GeneratorFunction: 5] AsyncFunction [Foobar] }"
  );
  Object.defineProperty(fn, 'name', { value: '5', configurable: true });
  Object.setPrototypeOf(fn, null);
  assert.strictEqual(
    util.inspect(fn),
    '[GeneratorFunction (null prototype): 5] [Foobar]'
  );
  assert.strictEqual(
    util.inspect({ ['5']: fn }),
    "{ '5': [GeneratorFunction (null prototype): 5] [Foobar] }"
  );
}

assert.strictEqual(util.inspect(undefined), 'undefined');
assert.strictEqual(util.inspect(null), 'null');
assert.strictEqual(util.inspect(/foo(bar\n)?/gi), '/foo(bar\\n)?/gi');
assert.strictEqual(
  util.inspect(new Date('Sun, 14 Feb 2010 11:48:40 GMT')),
  new Date('2010-02-14T12:48:40+01:00').toISOString()
);
assert.strictEqual(util.inspect(new Date('')), (new Date('')).toString());
assert.strictEqual(util.inspect('\n\x01'), "'\\n\\x01'");
assert.strictEqual(
  util.inspect(`${Array(75).fill(1)}'\n\x1d\n\x03\x85\x7f\x7e\x9f\xa0`),
  // eslint-disable-next-line no-irregular-whitespace
  `"${Array(75).fill(1)}'\\n" +\n  '\\x1D\\n' +\n  '\\x03\\x85\\x7F~\\x9F '`
);
assert.strictEqual(util.inspect([]), '[]');
assert.strictEqual(util.inspect(Object.create([])), 'Array {}');
assert.strictEqual(util.inspect([1, 2]), '[ 1, 2 ]');
assert.strictEqual(util.inspect([1, [2, 3]]), '[ 1, [ 2, 3 ] ]');
assert.strictEqual(util.inspect({}), '{}');
assert.strictEqual(util.inspect({ a: 1 }), '{ a: 1 }');
assert.strictEqual(util.inspect({ a: function() {} }), '{ a: [Function: a] }');
assert.strictEqual(util.inspect({ a: () => {} }), '{ a: [Function: a] }');
// eslint-disable-next-line func-name-matching
assert.strictEqual(util.inspect({ a: async function abc() {} }),
                   '{ a: [AsyncFunction: abc] }');
assert.strictEqual(util.inspect({ a: async () => {} }),
                   '{ a: [AsyncFunction: a] }');
assert.strictEqual(util.inspect({ a: function*() {} }),
                   '{ a: [GeneratorFunction: a] }');
assert.strictEqual(util.inspect({ a: 1, b: 2 }), '{ a: 1, b: 2 }');
assert.strictEqual(util.inspect({ 'a': {} }), '{ a: {} }');
assert.strictEqual(util.inspect({ 'a': { 'b': 2 } }), '{ a: { b: 2 } }');
assert.strictEqual(util.inspect({ 'a': { 'b': { 'c': { 'd': 2 } } } }),
                   '{ a: { b: { c: [Object] } } }');
assert.strictEqual(
  util.inspect({ 'a': { 'b': { 'c': { 'd': 2 } } } }, false, null),
  '{\n  a: { b: { c: { d: 2 } } }\n}');
assert.strictEqual(util.inspect([1, 2, 3], true), '[ 1, 2, 3, [length]: 3 ]');
assert.strictEqual(util.inspect({ 'a': { 'b': { 'c': 2 } } }, false, 0),
                   '{ a: [Object] }');
assert.strictEqual(util.inspect({ 'a': { 'b': { 'c': 2 } } }, false, 1),
                   '{ a: { b: [Object] } }');
assert.strictEqual(util.inspect({ 'a': { 'b': ['c'] } }, false, 1),
                   '{ a: { b: [Array] } }');
assert.strictEqual(util.inspect(new Uint8Array(0)), 'Uint8Array(0) []');
assert(inspect(new Uint8Array(0), { showHidden: true }).includes('[buffer]'));
assert.strictEqual(
  util.inspect(
    Object.create(
      {},
      { visible: { value: 1, enumerable: true }, hidden: { value: 2 } }
    )
  ),
  '{ visible: 1 }'
);
assert.strictEqual(
  util.inspect(
    Object.assign(new String('hello'), { [Symbol('foo')]: 123 }),
    { showHidden: true }
  ),
  "[String: 'hello'] { [length]: 5, [Symbol(foo)]: 123 }"
);

assert.match(util.inspect((new JSStream())._externalStream),
             /^\[External: [0-9a-f]+\]$/);

{
  const regexp = /regexp/;
  regexp.aprop = 42;
  assert.strictEqual(util.inspect({ a: regexp }, false, 0), '{ a: /regexp/ }');
}

assert.match(
  util.inspect({ a: { a: { a: { a: {} } } } }, undefined, undefined, true),
  /Object/
);
assert.doesNotMatch(
  util.inspect({ a: { a: { a: { a: {} } } } }, undefined, null, true),
  /Object/
);

{
  const showHidden = true;
  const ab = new Uint8Array([1, 2, 3, 4]).buffer;
  const dv = new DataView(ab, 1, 2);
  assert.strictEqual(
    util.inspect(ab, showHidden),
    'ArrayBuffer { [Uint8Contents]: <01 02 03 04>, byteLength: 4 }'
  );
  assert.strictEqual(util.inspect(new DataView(ab, 1, 2), showHidden),
                     'DataView {\n' +
                     '  byteLength: 2,\n' +
                     '  byteOffset: 1,\n' +
                     '  buffer: ArrayBuffer {' +
                      ' [Uint8Contents]: <01 02 03 04>, byteLength: 4 }\n}');
  assert.strictEqual(
    util.inspect(ab, showHidden),
    'ArrayBuffer { [Uint8Contents]: <01 02 03 04>, byteLength: 4 }'
  );
  assert.strictEqual(util.inspect(dv, showHidden),
                     'DataView {\n' +
                     '  byteLength: 2,\n' +
                     '  byteOffset: 1,\n' +
                     '  buffer: ArrayBuffer { [Uint8Contents]: ' +
                       '<01 02 03 04>, byteLength: 4 }\n}');
  ab.x = 42;
  dv.y = 1337;
  assert.strictEqual(util.inspect(ab, showHidden),
                     'ArrayBuffer { [Uint8Contents]: <01 02 03 04>, ' +
                       'byteLength: 4, x: 42 }');
  assert.strictEqual(util.inspect(dv, showHidden),
                     'DataView {\n' +
                     '  byteLength: 2,\n' +
                     '  byteOffset: 1,\n' +
                     '  buffer: ArrayBuffer { [Uint8Contents]: <01 02 03 04>,' +
                       ' byteLength: 4, x: 42 },\n' +
                     '  y: 1337\n}');
}

{
  const ab = new ArrayBuffer(42);
  assert.strictEqual(ab.byteLength, 42);
  new MessageChannel().port1.postMessage(ab, [ ab ]);
  assert.strictEqual(ab.byteLength, 0);
  assert.strictEqual(util.inspect(ab),
                     'ArrayBuffer { (detached), byteLength: 0 }');
}

// Truncate output for ArrayBuffers using plural or singular bytes
{
  const ab = new ArrayBuffer(3);
  assert.strictEqual(util.inspect(ab, { showHidden: true, maxArrayLength: 2 }),
                     'ArrayBuffer { [Uint8Contents]' +
                      ': <00 00 ... 1 more byte>, byteLength: 3 }');
  assert.strictEqual(util.inspect(ab, { showHidden: true, maxArrayLength: 1 }),
                     'ArrayBuffer { [Uint8Contents]' +
                      ': <00 ... 2 more bytes>, byteLength: 3 }');
}

// Now do the same checks but from a different context.
{
  const showHidden = false;
  const ab = vm.runInNewContext('new ArrayBuffer(4)');
  const dv = vm.runInNewContext('new DataView(ab, 1, 2)', { ab });
  assert.strictEqual(
    util.inspect(ab, showHidden),
    'ArrayBuffer { [Uint8Contents]: <00 00 00 00>, byteLength: 4 }'
  );
  assert.strictEqual(util.inspect(new DataView(ab, 1, 2), showHidden),
                     'DataView {\n' +
                     '  byteLength: 2,\n' +
                     '  byteOffset: 1,\n' +
                     '  buffer: ArrayBuffer { [Uint8Contents]: <00 00 00 00>,' +
                       ' byteLength: 4 }\n}');
  assert.strictEqual(
    util.inspect(ab, showHidden),
    'ArrayBuffer { [Uint8Contents]: <00 00 00 00>, byteLength: 4 }'
  );
  assert.strictEqual(util.inspect(dv, showHidden),
                     'DataView {\n' +
                     '  byteLength: 2,\n' +
                     '  byteOffset: 1,\n' +
                     '  buffer: ArrayBuffer { [Uint8Contents]: <00 00 00 00>,' +
                       ' byteLength: 4 }\n}');
  ab.x = 42;
  dv.y = 1337;
  assert.strictEqual(util.inspect(ab, showHidden),
                     'ArrayBuffer { [Uint8Contents]: <00 00 00 00>, ' +
                       'byteLength: 4, x: 42 }');
  assert.strictEqual(util.inspect(dv, showHidden),
                     'DataView {\n' +
                     '  byteLength: 2,\n' +
                     '  byteOffset: 1,\n' +
                     '  buffer: ArrayBuffer { [Uint8Contents]: <00 00 00 00>,' +
                       ' byteLength: 4, x: 42 },\n' +
                     '  y: 1337\n}');
}

[ Float32Array,
  Float64Array,
  Int16Array,
  Int32Array,
  Int8Array,
  Uint16Array,
  Uint32Array,
  Uint8Array,
  Uint8ClampedArray ].forEach((constructor) => {
  const length = 2;
  const byteLength = length * constructor.BYTES_PER_ELEMENT;
  const array = new constructor(new ArrayBuffer(byteLength), 0, length);
  array[0] = 65;
  array[1] = 97;
  assert.strictEqual(
    util.inspect(array, { showHidden: true }),
    `${constructor.name}(${length}) [\n` +
      '  65,\n' +
      '  97,\n' +
      `  [BYTES_PER_ELEMENT]: ${constructor.BYTES_PER_ELEMENT},\n` +
      `  [length]: ${length},\n` +
      `  [byteLength]: ${byteLength},\n` +
      '  [byteOffset]: 0,\n' +
      `  [buffer]: ArrayBuffer { byteLength: ${byteLength} }\n]`);
  assert.strictEqual(
    util.inspect(array, false),
    `${constructor.name}(${length}) [ 65, 97 ]`
  );
});

// Now check that declaring a TypedArray in a different context works the same.
[ Float32Array,
  Float64Array,
  Int16Array,
  Int32Array,
  Int8Array,
  Uint16Array,
  Uint32Array,
  Uint8Array,
  Uint8ClampedArray ].forEach((constructor) => {
  const length = 2;
  const byteLength = length * constructor.BYTES_PER_ELEMENT;
  const array = vm.runInNewContext(
    'new constructor(new ArrayBuffer(byteLength), 0, length)',
    { constructor, byteLength, length }
  );
  array[0] = 65;
  array[1] = 97;
  assert.strictEqual(
    util.inspect(array, true),
    `${constructor.name}(${length}) [\n` +
      '  65,\n' +
      '  97,\n' +
      `  [BYTES_PER_ELEMENT]: ${constructor.BYTES_PER_ELEMENT},\n` +
      `  [length]: ${length},\n` +
      `  [byteLength]: ${byteLength},\n` +
      '  [byteOffset]: 0,\n' +
      `  [buffer]: ArrayBuffer { byteLength: ${byteLength} }\n]`);
  assert.strictEqual(
    util.inspect(array, false),
    `${constructor.name}(${length}) [ 65, 97 ]`
  );
});

{
  const brokenLength = new Float32Array(2);
  Object.defineProperty(brokenLength, 'length', { value: -1 });
  assert.strictEqual(inspect(brokenLength), 'Float32Array(2) [ 0n, 0n ]');
}

assert.strictEqual(
  util.inspect(Object.create({}, {
    visible: { value: 1, enumerable: true },
    hidden: { value: 2 }
  }), { showHidden: true }),
  '{ visible: 1, [hidden]: 2 }'
);
// Objects without prototype.
assert.strictEqual(
  util.inspect(Object.create(null, {
    name: { value: 'Tim', enumerable: true },
    hidden: { value: 'secret' }
  }), { showHidden: true }),
  "[Object: null prototype] { name: 'Tim', [hidden]: 'secret' }"
);

assert.strictEqual(
  util.inspect(Object.create(null, {
    name: { value: 'Tim', enumerable: true },
    hidden: { value: 'secret' }
  })),
  "[Object: null prototype] { name: 'Tim' }"
);

// Dynamic properties.
{
  assert.strictEqual(
    util.inspect({ get readonly() { return 1; } }),
    '{ readonly: [Getter] }');

  assert.strictEqual(
    util.inspect({ get readwrite() { return 1; }, set readwrite(val) {} }),
    '{ readwrite: [Getter/Setter] }');

  assert.strictEqual(
    // eslint-disable-next-line accessor-pairs
    util.inspect({ set writeonly(val) {} }),
    '{ writeonly: [Setter] }');

  const value = {};
  value.a = value;
  assert.strictEqual(util.inspect(value), '<ref *1> { a: [Circular *1] }');
  const getterFn = {
    get one() {
      return null;
    }
  };
  assert.strictEqual(
    util.inspect(getterFn, { getters: true }),
    '{ one: [Getter: null] }'
  );
}

// Array with dynamic properties.
{
  const value = [1, 2, 3];
  Object.defineProperty(
    value,
    'growingLength',
    {
      enumerable: true,
      get: function() { this.push(true); return this.length; }
    }
  );
  Object.defineProperty(
    value,
    '-1',
    {
      enumerable: true,
      value: -1
    }
  );
  assert.strictEqual(util.inspect(value),
                     "[ 1, 2, 3, growingLength: [Getter], '-1': -1 ]");
}

// Array with inherited number properties.
{
  class CustomArray extends Array {}
  CustomArray.prototype[5] = 'foo';
  CustomArray.prototype[49] = 'bar';
  CustomArray.prototype.foo = true;
  const arr = new CustomArray(50);
  arr[49] = 'I win';
  assert.strictEqual(
    util.inspect(arr),
    "CustomArray(50) [ <49 empty items>, 'I win' ]"
  );
  assert.strictEqual(
    util.inspect(arr, { showHidden: true }),
    'CustomArray(50) [\n' +
    '  <49 empty items>,\n' +
    "  'I win',\n" +
    '  [length]: 50,\n' +
    "  '5': 'foo',\n" +
    '  foo: true\n' +
    ']'
  );
}

// Array with extra properties.
{
  const arr = [1, 2, 3, , ]; // eslint-disable-line no-sparse-arrays
  arr.foo = 'bar';
  assert.strictEqual(util.inspect(arr),
                     "[ 1, 2, 3, <1 empty item>, foo: 'bar' ]");

  const arr2 = [];
  assert.strictEqual(util.inspect([], { showHidden: true }), '[ [length]: 0 ]');
  arr2['00'] = 1;
  assert.strictEqual(util.inspect(arr2), "[ '00': 1 ]");
  assert.strictEqual(util.inspect(arr2, { showHidden: true }),
                     "[ [length]: 0, '00': 1 ]");
  arr2[1] = 0;
  assert.strictEqual(util.inspect(arr2), "[ <1 empty item>, 0, '00': 1 ]");
  assert.strictEqual(util.inspect(arr2, { showHidden: true }),
                     "[ <1 empty item>, 0, [length]: 2, '00': 1 ]");
  delete arr2[1];
  assert.strictEqual(util.inspect(arr2), "[ <2 empty items>, '00': 1 ]");
  assert.strictEqual(util.inspect(arr2, { showHidden: true }),
                     "[ <2 empty items>, [length]: 2, '00': 1 ]");
  arr2['01'] = 2;
  assert.strictEqual(util.inspect(arr2),
                     "[ <2 empty items>, '00': 1, '01': 2 ]");
  assert.strictEqual(util.inspect(arr2, { showHidden: true }),
                     "[ <2 empty items>, [length]: 2, '00': 1, '01': 2 ]");
  delete arr2['00'];
  arr2[0] = 0;
  assert.strictEqual(util.inspect(arr2),
                     "[ 0, <1 empty item>, '01': 2 ]");
  assert.strictEqual(util.inspect(arr2, { showHidden: true }),
                     "[ 0, <1 empty item>, [length]: 2, '01': 2 ]");
  delete arr2['01'];
  arr2[2 ** 32 - 2] = 'max';
  arr2[2 ** 32 - 1] = 'too far';
  assert.strictEqual(
    util.inspect(arr2),
    "[ 0, <4294967293 empty items>, 'max', '4294967295': 'too far' ]"
  );

  const arr3 = [];
  arr3[-1] = -1;
  assert.strictEqual(util.inspect(arr3), "[ '-1': -1 ]");
}

// Indices out of bounds.
{
  const arr = [];
  arr[2 ** 32] = true; // Not a valid array index.
  assert.strictEqual(util.inspect(arr), "[ '4294967296': true ]");
  arr[0] = true;
  arr[10] = true;
  assert.strictEqual(util.inspect(arr),
                     "[ true, <9 empty items>, true, '4294967296': true ]");
  arr[2 ** 32 - 2] = true;
  arr[2 ** 32 - 1] = true;
  arr[2 ** 32 + 1] = true;
  delete arr[0];
  delete arr[10];
  assert.strictEqual(util.inspect(arr),
                     ['[',
                      '<4294967294 empty items>,',
                      'true,',
                      "'4294967296': true,",
                      "'4294967295': true,",
                      "'4294967297': true\n]",
                     ].join('\n  '));
}

// Function with properties.
{
  const value = () => {};
  value.aprop = 42;
  assert.strictEqual(util.inspect(value), '[Function: value] { aprop: 42 }');
}

// Anonymous function with properties.
{
  const value = (() => function() {})();
  value.aprop = 42;
  assert.strictEqual(
    util.inspect(value),
    '[Function (anonymous)] { aprop: 42 }'
  );
}

// Regular expressions with properties.
{
  const value = /123/ig;
  value.aprop = 42;
  assert.strictEqual(util.inspect(value), '/123/gi { aprop: 42 }');
}

// Dates with properties.
{
  const value = new Date('Sun, 14 Feb 2010 11:48:40 GMT');
  value.aprop = 42;
  assert.strictEqual(util.inspect(value),
                     '2010-02-14T11:48:40.000Z { aprop: 42 }');
}

// Test the internal isDate implementation.
{
  const Date2 = vm.runInNewContext('Date');
  const d = new Date2();
  const orig = util.inspect(d);
  Date2.prototype.foo = 'bar';
  const after = util.inspect(d);
  assert.strictEqual(orig, after);
}

// Test positive/negative zero.
assert.strictEqual(util.inspect(0), '0');
assert.strictEqual(util.inspect(-0), '-0');
// Edge case from check.
assert.strictEqual(util.inspect(-5e-324), '-5e-324');

// Test for sparse array.
{
  const a = ['foo', 'bar', 'baz'];
  assert.strictEqual(util.inspect(a), "[ 'foo', 'bar', 'baz' ]");
  delete a[1];
  assert.strictEqual(util.inspect(a), "[ 'foo', <1 empty item>, 'baz' ]");
  assert.strictEqual(
    util.inspect(a, true),
    "[ 'foo', <1 empty item>, 'baz', [length]: 3 ]"
  );
  assert.strictEqual(util.inspect(new Array(5)), '[ <5 empty items> ]');
  a[3] = 'bar';
  a[100] = 'qux';
  assert.strictEqual(
    util.inspect(a, { breakLength: Infinity }),
    "[ 'foo', <1 empty item>, 'baz', 'bar', <96 empty items>, 'qux' ]"
  );
  delete a[3];
  assert.strictEqual(
    util.inspect(a, { maxArrayLength: 4 }),
    "[ 'foo', <1 empty item>, 'baz', <97 empty items>, ... 1 more item ]"
  );
  // test 4 special case
  assert.strictEqual(util.inspect(a, {
    maxArrayLength: 2
  }), "[ 'foo', <1 empty item>, ... 99 more items ]");
}

// Test for Array constructor in different context.
{
  const map = new Map();
  map.set(1, 2);
  // Passing only a single argument to indicate a set iterator.
  const valsSetIterator = previewEntries(map.entries());
  // Passing through true to indicate a map iterator.
  const valsMapIterEntries = previewEntries(map.entries(), true);
  const valsMapIterKeys = previewEntries(map.keys(), true);

  assert.strictEqual(util.inspect(valsSetIterator), '[ 1, 2 ]');
  assert.strictEqual(util.inspect(valsMapIterEntries), '[ [ 1, 2 ], true ]');
  assert.strictEqual(util.inspect(valsMapIterKeys), '[ [ 1 ], false ]');
}

// Test for other constructors in different context.
{
  let obj = vm.runInNewContext('(function(){return {}})()', {});
  assert.strictEqual(util.inspect(obj), '{}');
  obj = vm.runInNewContext('const m=new Map();m.set(1,2);m', {});
  assert.strictEqual(util.inspect(obj), 'Map(1) { 1 => 2 }');
  obj = vm.runInNewContext('const s=new Set();s.add(1);s.add(2);s', {});
  assert.strictEqual(util.inspect(obj), 'Set(2) { 1, 2 }');
  obj = vm.runInNewContext('fn=function(){};new Promise(fn,fn)', {});
  assert.strictEqual(util.inspect(obj), 'Promise { <pending> }');
}

// Test for property descriptors.
{
  const getter = Object.create(null, {
    a: {
      get: function() { return 'aaa'; }
    }
  });
  const setter = Object.create(null, {
    b: { // eslint-disable-line accessor-pairs
      set: function() {}
    }
  });
  const getterAndSetter = Object.create(null, {
    c: {
      get: function() { return 'ccc'; },
      set: function() {}
    }
  });
  assert.strictEqual(
    util.inspect(getter, true),
    '[Object: null prototype] { [a]: [Getter] }'
  );
  assert.strictEqual(
    util.inspect(setter, true),
    '[Object: null prototype] { [b]: [Setter] }'
  );
  assert.strictEqual(
    util.inspect(getterAndSetter, true),
    '[Object: null prototype] { [c]: [Getter/Setter] }'
  );
}

// Exceptions should print the error message, not '{}'.
{
  [
    new Error(),
    new Error('FAIL'),
    new TypeError('FAIL'),
    new SyntaxError('FAIL'),
  ].forEach((err) => {
    assert.strictEqual(util.inspect(err), err.stack);
  });
  assert.throws(
    () => undef(), // eslint-disable-line no-undef
    (e) => {
      assert.strictEqual(util.inspect(e), e.stack);
      return true;
    }
  );

  const ex = util.inspect(new Error('FAIL'), true);
  assert(ex.includes('Error: FAIL'));
  assert(ex.includes('[stack]'));
  assert(ex.includes('[message]'));
}

{
  const falsyCause1 = new Error('', { cause: false });
  delete falsyCause1.stack;
  const falsyCause2 = new Error(undefined, { cause: null });
  falsyCause2.stack = '';
  const undefinedCause = new Error('', { cause: undefined });
  undefinedCause.stack = '';

  assert.strictEqual(util.inspect(falsyCause1), '[Error] { [cause]: false }');
  assert.strictEqual(util.inspect(falsyCause2), '[Error] { [cause]: null }');
  assert.strictEqual(
    util.inspect(undefinedCause),
    '[Error] { [cause]: undefined }'
  );
}

{
  const tmp = Error.stackTraceLimit;
  Error.stackTraceLimit = 0;
  const err = new Error('foo');
  const err2 = new Error('foo\nbar');
  assert.strictEqual(util.inspect(err, { compact: true }), '[Error: foo]');
  assert(err.stack);
  delete err.stack;
  assert(!err.stack);
  assert.strictEqual(util.inspect(err, { compact: true }), '[Error: foo]');
  assert.strictEqual(
    util.inspect(err2, { compact: true }),
    '[Error: foo\nbar]'
  );

  err.bar = true;
  err2.bar = true;

  assert.strictEqual(
    util.inspect(err, { compact: true }),
    '{ [Error: foo] bar: true }'
  );
  assert.strictEqual(
    util.inspect(err2, { compact: true }),
    '{ [Error: foo\nbar]\n  bar: true }'
  );
  assert.strictEqual(
    util.inspect(err, { compact: true, breakLength: 5 }),
    '{ [Error: foo]\n  bar: true }'
  );
  assert.strictEqual(
    util.inspect(err, { compact: true, breakLength: 1 }),
    '{ [Error: foo]\n  bar:\n   true }'
  );
  assert.strictEqual(
    util.inspect(err2, { compact: true, breakLength: 5 }),
    '{ [Error: foo\nbar]\n  bar: true }'
  );
  assert.strictEqual(
    util.inspect(err, { compact: false }),
    '[Error: foo] {\n  bar: true\n}'
  );
  assert.strictEqual(
    util.inspect(err2, { compact: false }),
    '[Error: foo\nbar] {\n  bar: true\n}'
  );

  Error.stackTraceLimit = tmp;
}

// Prevent enumerable error properties from being printed.
{
  let err = new Error();
  err.message = 'foobar';
  let out = util.inspect(err).split('\n');
  assert.strictEqual(out[0], 'Error: foobar');
  assert(out[out.length - 1].startsWith('    at '));
  // Reset the error, the stack is otherwise not recreated.
  err = new Error();
  err.message = 'foobar';
  err.name = 'Unique';
  Object.defineProperty(err, 'stack', { value: err.stack, enumerable: true });
  out = util.inspect(err).split('\n');
  assert.strictEqual(out[0], 'Unique: foobar');
  assert(out[out.length - 1].startsWith('    at '));
  err.name = 'Baz';
  out = util.inspect(err).split('\n');
  assert.strictEqual(out[0], 'Unique: foobar');
  assert.strictEqual(out[out.length - 2], "  name: 'Baz'");
  assert.strictEqual(out[out.length - 1], '}');
}

// Doesn't capture stack trace.
{
  function BadCustomError(msg) {
    Error.call(this);
    Object.defineProperty(this, 'message',
                          { value: msg, enumerable: false });
    Object.defineProperty(this, 'name',
                          { value: 'BadCustomError', enumerable: false });
  }
  Object.setPrototypeOf(BadCustomError.prototype, Error.prototype);
  Object.setPrototypeOf(BadCustomError, Error);
  assert.strictEqual(
    util.inspect(new BadCustomError('foo')),
    '[BadCustomError: foo]'
  );
}

// Tampered error stack or name property (different type than string).
// Note: Symbols are not supported by `Error#toString()` which is called by
// accessing the `stack` property.
[
  [404, '404: foo', '[404]'],
  [0, '0: foo', '[RangeError: foo]'],
  [0n, '0: foo', '[RangeError: foo]'],
  [null, 'null: foo', '[RangeError: foo]'],
  [undefined, 'RangeError: foo', '[RangeError: foo]'],
  [false, 'false: foo', '[RangeError: foo]'],
  ['', 'foo', '[RangeError: foo]'],
  [[1, 2, 3], '1,2,3: foo', '[1,2,3]'],
].forEach(([value, outputStart, stack]) => {
  let err = new RangeError('foo');
  err.name = value;
  assert(
    util.inspect(err).startsWith(outputStart),
    util.format(
      'The name set to %o did not result in the expected output "%s"',
      value,
      outputStart
    )
  );

  err = new RangeError('foo');
  err.stack = value;
  assert.strictEqual(util.inspect(err), stack);
});

// https://github.com/nodejs/node-v0.x-archive/issues/1941
assert.strictEqual(util.inspect(Object.create(Date.prototype)), 'Date {}');

// https://github.com/nodejs/node-v0.x-archive/issues/1944
{
  const d = new Date();
  d.toUTCString = null;
  util.inspect(d);
}

// Should not throw.
{
  const d = new Date();
  d.toISOString = null;
  util.inspect(d);
}

// Should not throw.
{
  const r = /regexp/;
  r.toString = null;
  util.inspect(r);
}

// See https://github.com/nodejs/node-v0.x-archive/issues/2225
{
  const x = { [util.inspect.custom]: util.inspect };
  assert(util.inspect(x).includes(
    '[Symbol(nodejs.util.inspect.custom)]: [Function: inspect] {\n'));
}

// `util.inspect` should display the escaped value of a key.
{
  const w = {
    '\\': 1,
    '\\\\': 2,
    '\\\\\\': 3,
    '\\\\\\\\': 4,
    '\n': 5,
    '\r': 6
  };

  const y = ['a', 'b', 'c'];
  y['\\\\'] = 'd';
  y['\n'] = 'e';
  y['\r'] = 'f';

  assert.strictEqual(
    util.inspect(w),
    "{ '\\\\': 1, '\\\\\\\\': 2, '\\\\\\\\\\\\': 3, " +
    "'\\\\\\\\\\\\\\\\': 4, '\\n': 5, '\\r': 6 }"
  );
  assert.strictEqual(
    util.inspect(y),
    "[ 'a', 'b', 'c', '\\\\\\\\': 'd', " +
    "'\\n': 'e', '\\r': 'f' ]"
  );
}

// Escape unpaired surrogate pairs.
{
  const edgeChar = String.fromCharCode(0xd799);

  for (let charCode = 0xD800; charCode < 0xDFFF; charCode++) {
    const surrogate = String.fromCharCode(charCode);

    assert.strictEqual(
      util.inspect(surrogate),
      `'\\u${charCode.toString(16)}'`
    );
    assert.strictEqual(
      util.inspect(`${'a'.repeat(200)}${surrogate}`),
      `'${'a'.repeat(200)}\\u${charCode.toString(16)}'`
    );
    assert.strictEqual(
      util.inspect(`${surrogate}${'a'.repeat(200)}`),
      `'\\u${charCode.toString(16)}${'a'.repeat(200)}'`
    );
    if (charCode < 0xdc00) {
      const highSurrogate = surrogate;
      const lowSurrogate = String.fromCharCode(charCode + 1024);
      assert(
        !util.inspect(
          `${edgeChar}${highSurrogate}${lowSurrogate}${edgeChar}`
        ).includes('\\u')
      );
      assert.strictEqual(
        (util.inspect(
          `${highSurrogate}${highSurrogate}${lowSurrogate}`
        ).match(/\\u/g) ?? []).length,
        1
      );
    } else {
      assert.strictEqual(
        util.inspect(`${edgeChar}${surrogate}${edgeChar}`),
        `'${edgeChar}\\u${charCode.toString(16)}${edgeChar}'`
      );
    }
  }
}

// Test util.inspect.styles and util.inspect.colors.
{
  function testColorStyle(style, input, implicit) {
    const colorName = util.inspect.styles[style];
    let color = ['', ''];
    if (util.inspect.colors[colorName])
      color = util.inspect.colors[colorName];

    const withoutColor = util.inspect(input, false, 0, false);
    const withColor = util.inspect(input, false, 0, true);
    const expect = `\u001b[${color[0]}m${withoutColor}\u001b[${color[1]}m`;
    assert.strictEqual(
      withColor,
      expect,
      `util.inspect color for style ${style}`);
  }

  testColorStyle('special', function() {});
  testColorStyle('number', 123.456);
  testColorStyle('boolean', true);
  testColorStyle('undefined', undefined);
  testColorStyle('null', null);
  testColorStyle('string', 'test string');
  testColorStyle('date', new Date());
  testColorStyle('regexp', /regexp/);
}

// An object with "hasOwnProperty" overwritten should not throw.
util.inspect({ hasOwnProperty: null });

// New API, accepts an "options" object.
{
  const subject = { foo: 'bar', hello: 31, a: { b: { c: { d: 0 } } } };
  Object.defineProperty(subject, 'hidden', { enumerable: false, value: null });

  assert.strictEqual(
    util.inspect(subject, { showHidden: false }).includes('hidden'),
    false
  );
  assert.strictEqual(
    util.inspect(subject, { showHidden: true }).includes('hidden'),
    true
  );
  assert.strictEqual(
    util.inspect(subject, { colors: false }).includes('\u001b[32m'),
    false
  );
  assert.strictEqual(
    util.inspect(subject, { colors: true }).includes('\u001b[32m'),
    true
  );
  assert.strictEqual(
    util.inspect(subject, { depth: 2 }).includes('c: [Object]'),
    true
  );
  assert.strictEqual(
    util.inspect(subject, { depth: 0 }).includes('a: [Object]'),
    true
  );
  assert.strictEqual(
    util.inspect(subject, { depth: null }).includes('{ d: 0 }'),
    true
  );
  assert.strictEqual(
    util.inspect(subject, { depth: undefined }).includes('{ d: 0 }'),
    true
  );
}

{
  // "customInspect" option can enable/disable calling [util.inspect.custom]().
  const subject = { [util.inspect.custom]: () => 123 };

  assert.strictEqual(
    util.inspect(subject, { customInspect: true }).includes('123'),
    true
  );
  assert.strictEqual(
    util.inspect(subject, { customInspect: true }).includes('inspect'),
    false
  );
  assert.strictEqual(
    util.inspect(subject, { customInspect: false }).includes('123'),
    false
  );
  assert.strictEqual(
    util.inspect(subject, { customInspect: false }).includes('inspect'),
    true
  );

  // A custom [util.inspect.custom]() should be able to return other Objects.
  subject[util.inspect.custom] = () => ({ foo: 'bar' });

  assert.strictEqual(util.inspect(subject), "{ foo: 'bar' }");

  subject[util.inspect.custom] = common.mustCall((depth, opts, inspect) => {
    const clone = { ...opts };
    // This might change at some point but for now we keep the stylize function.
    // The function should either be documented or an alternative should be
    // implemented.
    assert.strictEqual(typeof opts.stylize, 'function');
    assert.strictEqual(opts.seen, undefined);
    assert.strictEqual(opts.budget, undefined);
    assert.strictEqual(opts.indentationLvl, undefined);
    assert.strictEqual(opts.showHidden, false);
    assert.strictEqual(inspect, util.inspect);
    assert.deepStrictEqual(
      new Set(Object.keys(inspect.defaultOptions).concat(['stylize'])),
      new Set(Object.keys(opts))
    );
    opts.showHidden = true;
    return { [inspect.custom]: common.mustCall((depth, opts2) => {
      assert.deepStrictEqual(clone, opts2);
    }) };
  });

  util.inspect(subject);

  // util.inspect.custom is a shared symbol which can be accessed as
  // Symbol.for("nodejs.util.inspect.custom").
  const inspect = Symbol.for('nodejs.util.inspect.custom');

  subject[inspect] = () => ({ baz: 'quux' });

  assert.strictEqual(util.inspect(subject), '{ baz: \'quux\' }');

  subject[inspect] = (depth, opts) => {
    assert.strictEqual(opts.customInspectOptions, true);
    assert.strictEqual(opts.seen, null);
    return {};
  };

  util.inspect(subject, { customInspectOptions: true, seen: null });
}

{
  const subject = { [util.inspect.custom]: common.mustCall((depth, opts) => {
    assert.strictEqual(depth, null);
    assert.strictEqual(opts.compact, true);
  }) };
  util.inspect(subject, { depth: null, compact: true });
}

{
  // Returning `this` from a custom inspection function works.
  const subject = { a: 123, [util.inspect.custom]() { return this; } };
  const UIC = 'nodejs.util.inspect.custom';
  assert.strictEqual(
    util.inspect(subject),
    `{\n  a: 123,\n  [Symbol(${UIC})]: [Function: [${UIC}]]\n}`
  );
}

// Verify that it's possible to use the stylize function to manipulate input.
assert.strictEqual(
  util.inspect([1, 2, 3], { stylize() { return 'x'; } }),
  '[ x, x, x ]'
);

// Using `util.inspect` with "colors" option should produce as many lines as
// without it.
{
  function testLines(input) {
    const countLines = (str) => (str.match(/\n/g) || []).length;
    const withoutColor = util.inspect(input);
    const withColor = util.inspect(input, { colors: true });
    assert.strictEqual(countLines(withoutColor), countLines(withColor));
  }

  const bigArray = new Array(100).fill().map((value, index) => index);

  testLines([1, 2, 3, 4, 5, 6, 7]);
  testLines(bigArray);
  testLines({ foo: 'bar', baz: 35, b: { a: 35 } });
  testLines({ a: { a: 3, b: 1, c: 1, d: 1, e: 1, f: 1, g: 1, h: 1 }, b: 1 });
  testLines({
    foo: 'bar',
    baz: 35,
    b: { a: 35 },
    veryLongKey: 'very long value',
    evenLongerKey: ['with even longer value in array']
  });
}

// Test boxed primitives output the correct values.
assert.strictEqual(util.inspect(new String('test')), "[String: 'test']");
assert.strictEqual(
  util.inspect(new String('test'), { colors: true }),
  "\u001b[32m[String: 'test']\u001b[39m"
);
assert.strictEqual(
  util.inspect(Object(Symbol('test'))),
  '[Symbol: Symbol(test)]'
);
assert.strictEqual(util.inspect(new Boolean(false)), '[Boolean: false]');
assert.strictEqual(
  util.inspect(Object.setPrototypeOf(new Boolean(true), null)),
  '[Boolean (null prototype): true]'
);
assert.strictEqual(util.inspect(new Number(0)), '[Number: 0]');
assert.strictEqual(
  util.inspect(
    Object.defineProperty(
      Object.setPrototypeOf(new Number(-0), Array.prototype),
      Symbol.toStringTag,
      { value: 'Foobar' }
    )
  ),
  '[Number (Array): -0] [Foobar]'
);
assert.strictEqual(util.inspect(new Number(-1.1)), '[Number: -1.1]');
assert.strictEqual(util.inspect(new Number(13.37)), '[Number: 13.37]');

// Test boxed primitives with own properties.
{
  const str = new String('baz');
  str.foo = 'bar';
  assert.strictEqual(util.inspect(str), "[String: 'baz'] { foo: 'bar' }");

  const bool = new Boolean(true);
  bool.foo = 'bar';
  assert.strictEqual(util.inspect(bool), "[Boolean: true] { foo: 'bar' }");

  const num = new Number(13.37);
  num.foo = 'bar';
  assert.strictEqual(util.inspect(num), "[Number: 13.37] { foo: 'bar' }");

  const sym = Object(Symbol('foo'));
  sym.foo = 'bar';
  assert.strictEqual(util.inspect(sym), "[Symbol: Symbol(foo)] { foo: 'bar' }");

  const big = Object(BigInt(55));
  big.foo = 'bar';
  assert.strictEqual(util.inspect(big), "[BigInt: 55n] { foo: 'bar' }");
}

// Test es6 Symbol.
if (typeof Symbol !== 'undefined') {
  assert.strictEqual(util.inspect(Symbol()), 'Symbol()');
  assert.strictEqual(util.inspect(Symbol(123)), 'Symbol(123)');
  assert.strictEqual(util.inspect(Symbol('hi')), 'Symbol(hi)');
  assert.strictEqual(util.inspect([Symbol()]), '[ Symbol() ]');
  assert.strictEqual(util.inspect({ foo: Symbol() }), '{ foo: Symbol() }');

  const options = { showHidden: true };
  let subject = {};

  subject[Symbol('sym\nbol')] = 42;

  assert.strictEqual(util.inspect(subject), '{ [Symbol(sym\\nbol)]: 42 }');
  assert.strictEqual(
    util.inspect(subject, options),
    '{ [Symbol(sym\\nbol)]: 42 }'
  );

  Object.defineProperty(
    subject,
    Symbol(),
    { enumerable: false, value: 'non-enum' });
  assert.strictEqual(util.inspect(subject), '{ [Symbol(sym\\nbol)]: 42 }');
  assert.strictEqual(
    util.inspect(subject, options),
    "{ [Symbol(sym\\nbol)]: 42, [Symbol()]: 'non-enum' }"
  );

  subject = [1, 2, 3];
  subject[Symbol('symbol')] = 42;

  assert.strictEqual(util.inspect(subject),
                     '[ 1, 2, 3, [Symbol(symbol)]: 42 ]');
}

// Test Set.
{
  assert.strictEqual(util.inspect(new Set()), 'Set(0) {}');
  assert.strictEqual(util.inspect(new Set([1, 2, 3])), 'Set(3) { 1, 2, 3 }');
  const set = new Set(['foo']);
  set.bar = 42;
  assert.strictEqual(
    util.inspect(set, { showHidden: true }),
    "Set(1) { 'foo', bar: 42 }"
  );
}

// Test circular Set.
{
  const set = new Set();
  set.add(set);
  assert.strictEqual(util.inspect(set), '<ref *1> Set(1) { [Circular *1] }');
}

// Test Map.
{
  assert.strictEqual(util.inspect(new Map()), 'Map(0) {}');
  assert.strictEqual(util.inspect(new Map([[1, 'a'], [2, 'b'], [3, 'c']])),
                     "Map(3) { 1 => 'a', 2 => 'b', 3 => 'c' }");
  const map = new Map([['foo', null]]);
  map.bar = 42;
  assert.strictEqual(util.inspect(map, true),
                     "Map(1) { 'foo' => null, bar: 42 }");
}

// Test circular Map.
{
  const map = new Map();
  map.set(map, 'map');
  assert.strictEqual(
    inspect(map),
    "<ref *1> Map(1) { [Circular *1] => 'map' }"
  );
  map.set(map, map);
  assert.strictEqual(
    inspect(map),
    '<ref *1> Map(1) { [Circular *1] => [Circular *1] }'
  );
  map.delete(map);
  map.set('map', map);
  assert.strictEqual(
    inspect(map),
    "<ref *1> Map(1) { 'map' => [Circular *1] }"
  );
}

// Test multiple circular references.
{
  const obj = {};
  obj.a = [obj];
  obj.b = {};
  obj.b.inner = obj.b;
  obj.b.obj = obj;

  assert.strictEqual(
    inspect(obj),
    '<ref *1> {\n' +
    '  a: [ [Circular *1] ],\n' +
    '  b: <ref *2> { inner: [Circular *2], obj: [Circular *1] }\n' +
    '}'
  );
}

// Test Promise.
{
  const resolved = Promise.resolve(3);
  assert.strictEqual(util.inspect(resolved), 'Promise { 3 }');

  const rejected = Promise.reject(3);
  assert.strictEqual(util.inspect(rejected), 'Promise { <rejected> 3 }');
  // Squelch UnhandledPromiseRejection.
  rejected.catch(() => {});

  const pending = new Promise(() => {});
  assert.strictEqual(util.inspect(pending), 'Promise { <pending> }');

  const promiseWithProperty = Promise.resolve('foo');
  promiseWithProperty.bar = 42;
  assert.strictEqual(util.inspect(promiseWithProperty),
                     "Promise { 'foo', bar: 42 }");
}

// Make sure it doesn't choke on polyfills. Unlike Set/Map, there is no standard
// interface to synchronously inspect a Promise, so our techniques only work on
// a bonafide native Promise.
{
  const oldPromise = Promise;
  global.Promise = function() { this.bar = 42; };
  assert.strictEqual(util.inspect(new Promise()), '{ bar: 42 }');
  global.Promise = oldPromise;
}

// Test Map iterators.
{
  const map = new Map([['foo', 'bar']]);
  assert.strictEqual(util.inspect(map.keys()), '[Map Iterator] { \'foo\' }');
  const mapValues = map.values();
  Object.defineProperty(mapValues, Symbol.toStringTag, { value: 'Foo' });
  assert.strictEqual(
    util.inspect(mapValues),
    '[Foo] [Map Iterator] { \'bar\' }'
  );
  map.set('A', 'B!');
  assert.strictEqual(util.inspect(map.entries(), { maxArrayLength: 1 }),
                     "[Map Entries] { [ 'foo', 'bar' ], ... 1 more item }");
  // Make sure the iterator doesn't get consumed.
  const keys = map.keys();
  assert.strictEqual(util.inspect(keys), "[Map Iterator] { 'foo', 'A' }");
  assert.strictEqual(util.inspect(keys), "[Map Iterator] { 'foo', 'A' }");
  keys.extra = true;
  assert.strictEqual(
    util.inspect(keys, { maxArrayLength: 0 }),
    '[Map Iterator] { ... 2 more items, extra: true }');
}

// Test Set iterators.
{
  const aSet = new Set([1]);
  assert.strictEqual(util.inspect(aSet.entries(), { compact: false }),
                     '[Set Entries] {\n  [\n    1,\n    1\n  ]\n}');
  aSet.add(3);
  assert.strictEqual(util.inspect(aSet.keys()), '[Set Iterator] { 1, 3 }');
  assert.strictEqual(util.inspect(aSet.values()), '[Set Iterator] { 1, 3 }');
  const setEntries = aSet.entries();
  Object.defineProperty(setEntries, Symbol.toStringTag, { value: 'Foo' });
  assert.strictEqual(util.inspect(setEntries),
                     '[Foo] [Set Entries] { [ 1, 1 ], [ 3, 3 ] }');
  // Make sure the iterator doesn't get consumed.
  const keys = aSet.keys();
  Object.defineProperty(keys, Symbol.toStringTag, { value: null });
  assert.strictEqual(util.inspect(keys), '[Set Iterator] { 1, 3 }');
  assert.strictEqual(util.inspect(keys), '[Set Iterator] { 1, 3 }');
  keys.extra = true;
  assert.strictEqual(
    util.inspect(keys, { maxArrayLength: 1 }),
    '[Set Iterator] { 1, ... 1 more item, extra: true }');
}

// Minimal inspection should still return as much information as possible about
// the constructor and Symbol.toStringTag.
{
  class Foo {
    get [Symbol.toStringTag]() {
      return 'ABC';
    }
  }
  const a = new Foo();
  assert.strictEqual(inspect(a, { depth: -1 }), 'Foo [ABC] {}');
  a.foo = true;
  assert.strictEqual(inspect(a, { depth: -1 }), '[Foo [ABC]]');
  Object.defineProperty(a, Symbol.toStringTag, {
    value: 'Foo',
    configurable: true,
    writable: true
  });
  assert.strictEqual(inspect(a, { depth: -1 }), '[Foo]');
  delete a[Symbol.toStringTag];
  Object.setPrototypeOf(a, null);
  assert.strictEqual(inspect(a, { depth: -1 }), '[Foo: null prototype]');
  delete a.foo;
  assert.strictEqual(inspect(a, { depth: -1 }), '[Foo: null prototype] {}');
  Object.defineProperty(a, Symbol.toStringTag, {
    value: 'ABC',
    configurable: true
  });
  assert.strictEqual(
    inspect(a, { depth: -1 }),
    '[Foo: null prototype] [ABC] {}'
  );
  Object.defineProperty(a, Symbol.toStringTag, {
    value: 'Foo',
    configurable: true
  });
  assert.strictEqual(
    inspect(a, { depth: -1 }),
    '[Object: null prototype] [Foo] {}'
  );
}

// Test alignment of items in container.
// Assumes that the first numeric character is the start of an item.
{
  function checkAlignment(container, start, lineX, end) {
    const lines = util.inspect(container).split('\n');
    lines.forEach((line, i) => {
      if (i === 0) {
        assert.strictEqual(line, start);
      } else if (i === lines.length - 1) {
        assert.strictEqual(line, end);
      } else {
        let expected = lineX.replace('X', i - 1);
        if (i !== lines.length - 2)
          expected += ',';
        assert.strictEqual(line, expected);
      }
    });
  }

  const bigArray = [];
  for (let i = 0; i < 100; i++) {
    bigArray.push(i);
  }

  const obj = {};
  bigArray.forEach((prop) => {
    obj[prop] = null;
  });

  checkAlignment(obj, '{', "  'X': null", '}');
  checkAlignment(new Set(bigArray), 'Set(100) {', '  X', '}');
  checkAlignment(
    new Map(bigArray.map((number) => [number, null])),
    'Map(100) {', '  X => null', '}'
  );
}


// Test display of constructors.
{
  class ObjectSubclass {}
  class ArraySubclass extends Array {}
  class SetSubclass extends Set {}
  class MapSubclass extends Map {}
  class PromiseSubclass extends Promise {}

  const x = new ObjectSubclass();
  x.foo = 42;
  assert.strictEqual(util.inspect(x),
                     'ObjectSubclass { foo: 42 }');
  assert.strictEqual(util.inspect(new ArraySubclass(1, 2, 3)),
                     'ArraySubclass(3) [ 1, 2, 3 ]');
  assert.strictEqual(util.inspect(new SetSubclass([1, 2, 3])),
                     'SetSubclass(3) [Set] { 1, 2, 3 }');
  assert.strictEqual(util.inspect(new MapSubclass([['foo', 42]])),
                     "MapSubclass(1) [Map] { 'foo' => 42 }");
  assert.strictEqual(util.inspect(new PromiseSubclass(() => {})),
                     'PromiseSubclass [Promise] { <pending> }');
  assert.strictEqual(
    util.inspect({ a: { b: new ArraySubclass([1, [2], 3]) } }, { depth: 1 }),
    '{ a: { b: [ArraySubclass] } }'
  );
  assert.strictEqual(
    util.inspect(Object.setPrototypeOf(x, null)),
    '[ObjectSubclass: null prototype] { foo: 42 }'
  );
}

// Empty and circular before depth.
{
  const arr = [[[[]]]];
  assert.strictEqual(util.inspect(arr), '[ [ [ [] ] ] ]');
  arr[0][0][0][0] = [];
  assert.strictEqual(util.inspect(arr), '[ [ [ [Array] ] ] ]');
  arr[0][0][0] = {};
  assert.strictEqual(util.inspect(arr), '[ [ [ {} ] ] ]');
  arr[0][0][0] = { a: 2 };
  assert.strictEqual(util.inspect(arr), '[ [ [ [Object] ] ] ]');
  arr[0][0][0] = arr;
  assert.strictEqual(util.inspect(arr), '<ref *1> [ [ [ [Circular *1] ] ] ]');
  arr[0][0][0] = arr[0][0];
  assert.strictEqual(util.inspect(arr), '[ [ <ref *1> [ [Circular *1] ] ] ]');
}

// Corner cases.
{
  const x = { constructor: 42 };
  assert.strictEqual(util.inspect(x), '{ constructor: 42 }');
}

{
  const x = {};
  Object.defineProperty(x, 'constructor', {
    get: function() {
      throw new Error('should not access constructor');
    },
    enumerable: true
  });
  assert.strictEqual(util.inspect(x), '{ constructor: [Getter] }');
}

{
  const x = new function() {}; // eslint-disable-line new-parens
  assert.strictEqual(util.inspect(x), '{}');
}

{
  const x = Object.create(null);
  assert.strictEqual(util.inspect(x), '[Object: null prototype] {}');
}

{
  const x = [];
  x[''] = 1;
  assert.strictEqual(util.inspect(x), "[ '': 1 ]");
}

// The following maxArrayLength tests were introduced after v6.0.0 was released.
// Do not backport to v5/v4 unless all of
// https://github.com/nodejs/node/pull/6334 is backported.
{
  const x = new Array(101).fill();
  assert(util.inspect(x).endsWith('1 more item\n]'));
  assert(!util.inspect(x, { maxArrayLength: 101 }).endsWith('1 more item\n]'));
  assert.strictEqual(
    util.inspect(x, { maxArrayLength: -1 }),
    '[ ... 101 more items ]'
  );
  assert.strictEqual(util.inspect(x, { maxArrayLength: 0 }),
                     '[ ... 101 more items ]');
}

{
  const x = Array(101);
  assert.strictEqual(util.inspect(x, { maxArrayLength: 0 }),
                     '[ ... 101 more items ]');
  assert(!util.inspect(x, { maxArrayLength: null }).endsWith('1 more item\n]'));
  assert(!util.inspect(
    x, { maxArrayLength: Infinity }
  ).endsWith('1 more item ]'));
}

{
  const x = new Uint8Array(101);
  assert(util.inspect(x).endsWith('1 more item\n]'));
  assert(!util.inspect(x, { maxArrayLength: 101 }).includes('1 more item'));
  assert.strictEqual(util.inspect(x, { maxArrayLength: 0 }),
                     'Uint8Array(101) [ ... 101 more items ]');
  assert(!util.inspect(x, { maxArrayLength: null }).includes('1 more item'));
  assert(util.inspect(x, { maxArrayLength: Infinity }).endsWith(' 0, 0\n]'));
}

{
  const obj = { foo: 'abc', bar: 'xyz' };
  const oneLine = util.inspect(obj, { breakLength: Infinity });
  // Subtract four for the object's two curly braces and two spaces of padding.
  // Add one more to satisfy the strictly greater than condition in the code.
  const breakpoint = oneLine.length - 5;
  const twoLines = util.inspect(obj, { breakLength: breakpoint });

  assert.strictEqual(oneLine, "{ foo: 'abc', bar: 'xyz' }");
  assert.strictEqual(
    util.inspect(obj, { breakLength: breakpoint + 1 }),
    twoLines
  );
  assert.strictEqual(twoLines, "{\n  foo: 'abc',\n  bar: 'xyz'\n}");
}

// util.inspect.defaultOptions tests.
{
  const arr = new Array(101).fill();
  const obj = { a: { a: { a: { a: 1 } } } };

  const oldOptions = { ...util.inspect.defaultOptions };

  // Set single option through property assignment.
  util.inspect.defaultOptions.maxArrayLength = null;
  assert.doesNotMatch(util.inspect(arr), /1 more item/);
  util.inspect.defaultOptions.maxArrayLength = oldOptions.maxArrayLength;
  assert.match(util.inspect(arr), /1 more item/);
  util.inspect.defaultOptions.depth = null;
  assert.doesNotMatch(util.inspect(obj), /Object/);
  util.inspect.defaultOptions.depth = oldOptions.depth;
  assert.match(util.inspect(obj), /Object/);
  assert.strictEqual(
    JSON.stringify(util.inspect.defaultOptions),
    JSON.stringify(oldOptions)
  );

  // Set multiple options through object assignment.
  util.inspect.defaultOptions = { maxArrayLength: null, depth: 2 };
  assert.doesNotMatch(util.inspect(arr), /1 more item/);
  assert.match(util.inspect(obj), /Object/);
  util.inspect.defaultOptions = oldOptions;
  assert.match(util.inspect(arr), /1 more item/);
  assert.match(util.inspect(obj), /Object/);
  assert.strictEqual(
    JSON.stringify(util.inspect.defaultOptions),
    JSON.stringify(oldOptions)
  );

  assert.throws(() => {
    util.inspect.defaultOptions = null;
  }, {
    code: 'ERR_INVALID_ARG_TYPE',
    name: 'TypeError',
    message: 'The "options" argument must be of type object. ' +
             'Received null'
  }
  );

  assert.throws(() => {
    util.inspect.defaultOptions = 'bad';
  }, {
    code: 'ERR_INVALID_ARG_TYPE',
    name: 'TypeError',
    message: 'The "options" argument must be of type object. ' +
             "Received type string ('bad')"
  }
  );
}

util.inspect(process);

// Setting custom inspect property to a non-function should do nothing.
{
  const obj = { [util.inspect.custom]: 'fhqwhgads' };
  assert.strictEqual(
    util.inspect(obj),
    "{ [Symbol(nodejs.util.inspect.custom)]: 'fhqwhgads' }"
  );
}

{
  // @@toStringTag
  const obj = { [Symbol.toStringTag]: 'a' };
  assert.strictEqual(
    util.inspect(obj),
    "{ [Symbol(Symbol.toStringTag)]: 'a' }"
  );
  Object.defineProperty(obj, Symbol.toStringTag, {
    value: 'a',
    enumerable: false
  });
  assert.strictEqual(util.inspect(obj), 'Object [a] {}');
  assert.strictEqual(
    util.inspect(obj, { showHidden: true }),
    "{ [Symbol(Symbol.toStringTag)]: 'a' }"
  );

  class Foo {
    constructor() {
      this.foo = 'bar';
    }

    get [Symbol.toStringTag]() {
      return this.foo;
    }
  }

  assert.strictEqual(util.inspect(
    Object.create(null, { [Symbol.toStringTag]: { value: 'foo' } })),
                     '[Object: null prototype] [foo] {}');

  assert.strictEqual(util.inspect(new Foo()), "Foo [bar] { foo: 'bar' }");

  assert.strictEqual(
    util.inspect(new (class extends Foo {})()),
    "Foo [bar] { foo: 'bar' }");

  assert.strictEqual(
    util.inspect(Object.create(Object.create(Foo.prototype), {
      foo: { value: 'bar', enumerable: true }
    })),
    "Foo [bar] { foo: 'bar' }");

  class ThrowingClass {
    get [Symbol.toStringTag]() {
      throw new Error('toStringTag error');
    }
  }

  assert.throws(() => util.inspect(new ThrowingClass()), /toStringTag error/);

  class NotStringClass {
    get [Symbol.toStringTag]() {
      return null;
    }
  }

  assert.strictEqual(util.inspect(new NotStringClass()),
                     'NotStringClass {}');
}

{
  const o = {
    a: [1, 2, [[
      'Lorem ipsum dolor\nsit amet,\tconsectetur adipiscing elit, sed do ' +
        'eiusmod tempor incididunt ut labore et dolore magna aliqua.',
      'test',
      'foo']], 4],
    b: new Map([['za', 1], ['zb', 'test']])
  };

  let out = util.inspect(o, { compact: true, depth: 5, breakLength: 80 });
  let expect = [
    '{ a:',
    '   [ 1,',
    '     2,',
    "     [ [ 'Lorem ipsum dolor\\nsit amet,\\tconsectetur adipiscing elit, " +
      "sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.',",
    "         'test',",
    "         'foo' ] ],",
    '     4 ],',
    "  b: Map(2) { 'za' => 1, 'zb' => 'test' } }",
  ].join('\n');
  assert.strictEqual(out, expect);

  out = util.inspect(o, { compact: false, depth: 5, breakLength: 60 });
  expect = [
    '{',
    '  a: [',
    '    1,',
    '    2,',
    '    [',
    '      [',
    "        'Lorem ipsum dolor\\n' +",
    "          'sit amet,\\tconsectetur adipiscing elit, sed do eiusmod " +
      "tempor incididunt ut labore et dolore magna aliqua.',",
    "        'test',",
    "        'foo'",
    '      ]',
    '    ],',
    '    4',
    '  ],',
    '  b: Map(2) {',
    "    'za' => 1,",
    "    'zb' => 'test'",
    '  }',
    '}',
  ].join('\n');
  assert.strictEqual(out, expect);

  out = util.inspect(o.a[2][0][0], { compact: false, breakLength: 30 });
  expect = [
    "'Lorem ipsum dolor\\n' +",
    "  'sit amet,\\tconsectetur adipiscing elit, sed do eiusmod tempor " +
      "incididunt ut labore et dolore magna aliqua.'",
  ].join('\n');
  assert.strictEqual(out, expect);

  out = util.inspect(
    '12345678901234567890123456789012345678901234567890',
    { compact: false, breakLength: 3 });
  expect = "'12345678901234567890123456789012345678901234567890'";
  assert.strictEqual(out, expect);

  out = util.inspect(
    '12 45 78 01 34 67 90 23 56 89 123456789012345678901234567890',
    { compact: false, breakLength: 3 });
  expect = [
    "'12 45 78 01 34 67 90 23 56 89 123456789012345678901234567890'",
  ].join('\n');
  assert.strictEqual(out, expect);

  o.a = () => {};
  o.b = new Number(3);
  out = util.inspect(o, { compact: false, breakLength: 3 });
  expect = [
    '{',
    '  a: [Function (anonymous)],',
    '  b: [Number: 3]',
    '}',
  ].join('\n');
  assert.strictEqual(out, expect);

  out = util.inspect(o, { compact: false, breakLength: 3, showHidden: true });
  expect = [
    '{',
    '  a: [Function (anonymous)] {',
    '    [length]: 0,',
    "    [name]: ''",
    '  },',
    '  b: [Number: 3]',
    '}',
  ].join('\n');
  assert.strictEqual(out, expect);

  o[util.inspect.custom] = () => 42;
  out = util.inspect(o, { compact: false, breakLength: 3 });
  expect = '42';
  assert.strictEqual(out, expect);

  o[util.inspect.custom] = () => '12 45 78 01 34 67 90 23';
  out = util.inspect(o, { compact: false, breakLength: 3 });
  expect = '12 45 78 01 34 67 90 23';
  assert.strictEqual(out, expect);

  o[util.inspect.custom] = () => ({ a: '12 45 78 01 34 67 90 23' });
  out = util.inspect(o, { compact: false, breakLength: 3 });
  expect = "{\n  a: '12 45 78 01 34 67 90 23'\n}";
  assert.strictEqual(out, expect);
}

// Check compact indentation.
{
  const typed = new Uint8Array();
  typed.buffer.foo = true;
  const set = new Set([[1, 2]]);
  const promise = Promise.resolve([[1, set]]);
  const map = new Map([[promise, typed]]);
  map.set(set.values(), map.values());

  let out = util.inspect(map, { compact: false, showHidden: true, depth: 9 });
  let expected = [
    'Map(2) {',
    '  Promise {',
    '    [',
    '      [',
    '        1,',
    '        Set(1) {',
    '          [',
    '            1,',
    '            2,',
    '            [length]: 2',
    '          ]',
    '        },',
    '        [length]: 2',
    '      ],',
    '      [length]: 1',
    '    ]',
    '  } => Uint8Array(0) [',
    '    [BYTES_PER_ELEMENT]: 1,',
    '    [length]: 0,',
    '    [byteLength]: 0,',
    '    [byteOffset]: 0,',
    '    [buffer]: ArrayBuffer {',
    '      byteLength: 0,',
    '      foo: true',
    '    }',
    '  ],',
    '  [Set Iterator] {',
    '    [',
    '      1,',
    '      2,',
    '      [length]: 2',
    '    ],',
    "    [Symbol(Symbol.toStringTag)]: 'Set Iterator'",
    '  } => <ref *1> [Map Iterator] {',
    '    Uint8Array(0) [',
    '      [BYTES_PER_ELEMENT]: 1,',
    '      [length]: 0,',
    '      [byteLength]: 0,',
    '      [byteOffset]: 0,',
    '      [buffer]: ArrayBuffer {',
    '        byteLength: 0,',
    '        foo: true',
    '      }',
    '    ],',
    '    [Circular *1],',
    "    [Symbol(Symbol.toStringTag)]: 'Map Iterator'",
    '  }',
    '}',
  ].join('\n');

  assert.strict.equal(out, expected);

  out = util.inspect(map, { compact: 2, showHidden: true, depth: 9 });

  expected = [
    'Map(2) {',
    '  Promise {',
    '    [',
    '      [',
    '        1,',
    '        Set(1) { [ 1, 2, [length]: 2 ] },',
    '        [length]: 2',
    '      ],',
    '      [length]: 1',
    '    ]',
    '  } => Uint8Array(0) [',
    '    [BYTES_PER_ELEMENT]: 1,',
    '    [length]: 0,',
    '    [byteLength]: 0,',
    '    [byteOffset]: 0,',
    '    [buffer]: ArrayBuffer { byteLength: 0, foo: true }',
    '  ],',
    '  [Set Iterator] {',
    '    [ 1, 2, [length]: 2 ],',
    "    [Symbol(Symbol.toStringTag)]: 'Set Iterator'",
    '  } => <ref *1> [Map Iterator] {',
    '    Uint8Array(0) [',
    '      [BYTES_PER_ELEMENT]: 1,',
    '      [length]: 0,',
    '      [byteLength]: 0,',
    '      [byteOffset]: 0,',
    '      [buffer]: ArrayBuffer { byteLength: 0, foo: true }',
    '    ],',
    '    [Circular *1],',
    "    [Symbol(Symbol.toStringTag)]: 'Map Iterator'",
    '  }',
    '}',
  ].join('\n');

  assert.strict.equal(out, expected);

  out = util.inspect(map, {
    showHidden: true, depth: 9, breakLength: 4, compact: true
  });
  expected = [
    'Map(2) {',
    '  Promise {',
    '    [ [ 1,',
    '        Set(1) {',
    '          [ 1,',
    '            2,',
    '            [length]: 2 ] },',
    '        [length]: 2 ],',
    '      [length]: 1 ] } => Uint8Array(0) [',
    '    [BYTES_PER_ELEMENT]: 1,',
    '    [length]: 0,',
    '    [byteLength]: 0,',
    '    [byteOffset]: 0,',
    '    [buffer]: ArrayBuffer {',
    '      byteLength: 0,',
    '      foo: true } ],',
    '  [Set Iterator] {',
    '    [ 1,',
    '      2,',
    '      [length]: 2 ],',
    '    [Symbol(Symbol.toStringTag)]:',
    "     'Set Iterator' } => <ref *1> [Map Iterator] {",
    '    Uint8Array(0) [',
    '      [BYTES_PER_ELEMENT]: 1,',
    '      [length]: 0,',
    '      [byteLength]: 0,',
    '      [byteOffset]: 0,',
    '      [buffer]: ArrayBuffer {',
    '        byteLength: 0,',
    '        foo: true } ],',
    '    [Circular *1],',
    '    [Symbol(Symbol.toStringTag)]:',
    "     'Map Iterator' } }",
  ].join('\n');

  assert.strict.equal(out, expected);
}

{ // Test WeakMap && WeakSet
  const obj = {};
  const arr = [];
  const weakMap = new WeakMap([[obj, arr], [arr, obj]]);
  let out = util.inspect(weakMap, { showHidden: true });
  let expect = 'WeakMap { [ [length]: 0 ] => {}, {} => [ [length]: 0 ] }';
  assert.strictEqual(out, expect);

  out = util.inspect(weakMap);
  expect = 'WeakMap { <items unknown> }';
  assert.strictEqual(out, expect);

  out = util.inspect(weakMap, { maxArrayLength: 0, showHidden: true });
  expect = 'WeakMap { ... 2 more items }';
  assert.strictEqual(out, expect);

  weakMap.extra = true;
  out = util.inspect(weakMap, { maxArrayLength: 1, showHidden: true });
  // It is not possible to determine the output reliable.
  expect = 'WeakMap { [ [length]: 0 ] => {}, ... 1 more item, extra: true }';
  let expectAlt = 'WeakMap { {} => [ [length]: 0 ], ... 1 more item, ' +
                  'extra: true }';
  assert(out === expect || out === expectAlt,
         `Found: "${out}"\nrather than: "${expect}"\nor: "${expectAlt}"`);

  // Test WeakSet
  arr.push(1);
  const weakSet = new WeakSet([obj, arr]);
  out = util.inspect(weakSet, { showHidden: true });
  expect = 'WeakSet { [ 1, [length]: 1 ], {} }';
  assert.strictEqual(out, expect);

  out = util.inspect(weakSet);
  expect = 'WeakSet { <items unknown> }';
  assert.strictEqual(out, expect);

  out = util.inspect(weakSet, { maxArrayLength: -2, showHidden: true });
  expect = 'WeakSet { ... 2 more items }';
  assert.strictEqual(out, expect);

  weakSet.extra = true;
  out = util.inspect(weakSet, { maxArrayLength: 1, showHidden: true });
  // It is not possible to determine the output reliable.
  expect = 'WeakSet { {}, ... 1 more item, extra: true }';
  expectAlt = 'WeakSet { [ 1, [length]: 1 ], ... 1 more item, extra: true }';
  assert(out === expect || out === expectAlt,
         `Found: "${out}"\nrather than: "${expect}"\nor: "${expectAlt}"`);
  // Keep references to the WeakMap entries, otherwise they could be GCed too
  // early.
  assert(obj && arr);
}

{ // Test argument objects.
  const args = (function() { return arguments; })('a');
  assert.strictEqual(util.inspect(args), "[Arguments] { '0': 'a' }");
}

{
  // Test that a long linked list can be inspected without throwing an error.
  const list = {};
  let head = list;
  // A linked list of length 100k should be inspectable in some way, even though
  // the real cutoff value is much lower than 100k.
  for (let i = 0; i < 100000; i++)
    head = head.next = {};
  assert.strictEqual(
    util.inspect(list),
    '{ next: { next: { next: [Object] } } }'
  );
  const longList = util.inspect(list, { depth: Infinity });
  const match = longList.match(/next/g);
  assert(match.length > 500 && match.length < 10000);
  assert(longList.includes('[Object: Inspection interrupted ' +
    'prematurely. Maximum call stack size exceeded.]'));
}

// Do not escape single quotes if no double quote or backtick is present.
assert.strictEqual(util.inspect("'"), '"\'"');
assert.strictEqual(util.inspect('"\''), '`"\'`');
// eslint-disable-next-line no-template-curly-in-string
assert.strictEqual(util.inspect('"\'${a}'), "'\"\\'${a}'");

// Errors should visualize as much information as possible.
// If the name is not included in the stack, visualize it as well.
[
  [class Foo extends TypeError {}, 'test'],
  [class Foo extends TypeError {}, undefined],
  [class BarError extends Error {}, 'test'],
  [class BazError extends Error {
    get name() {
      return 'BazError';
    }
  }, undefined],
].forEach(([Class, message], i) => {
  console.log('Test %i', i);
  const foo = new Class(message);
  const name = foo.name;
  const extra = Class.name.includes('Error') ? '' : ` [${foo.name}]`;
  assert(
    util.inspect(foo).startsWith(
      `${Class.name}${extra}${message ? `: ${message}` : '\n'}`),
    util.inspect(foo)
  );
  Object.defineProperty(foo, Symbol.toStringTag, {
    value: 'WOW',
    writable: true,
    configurable: true
  });
  const stack = foo.stack;
  foo.stack = 'This is a stack';
  assert.strictEqual(
    util.inspect(foo),
    '[This is a stack]'
  );
  foo.stack = stack;
  assert(
    util.inspect(foo).startsWith(
      `${Class.name} [WOW]${extra}${message ? `: ${message}` : '\n'}`),
    util.inspect(foo)
  );
  Object.setPrototypeOf(foo, null);
  assert(
    util.inspect(foo).startsWith(
      `[${name}: null prototype] [WOW]${message ? `: ${message}` : '\n'}`
    ),
    util.inspect(foo)
  );
  foo.bar = true;
  delete foo[Symbol.toStringTag];
  assert(
    util.inspect(foo).startsWith(
      `[${name}: null prototype]${message ? `: ${message}` : '\n'}`),
    util.inspect(foo)
  );
  foo.stack = 'This is a stack';
  assert.strictEqual(
    util.inspect(foo),
    '[[Error: null prototype]: This is a stack] { bar: true }'
  );
  foo.stack = stack.split('\n')[0];
  assert.strictEqual(
    util.inspect(foo),
    `[[${name}: null prototype]${message ? `: ${message}` : ''}] { bar: true }`
  );
});

// Verify that classes are properly inspected.
[
  /* eslint-disable spaced-comment, no-multi-spaces, brace-style */
  // The whitespace is intentional.
  [class   { }, '[class (anonymous)]'],
  [class extends Error { log() {} }, '[class (anonymous) extends Error]'],
  [class A { constructor(a) { this.a = a; } log() { return this.a; } },
   '[class A]'],
  [class
  // Random { // comments /* */ are part of the toString() result
  /* eslint-disable-next-line space-before-blocks */
  äß/**/extends/*{*/TypeError{}, '[class äß extends TypeError]'],
  /* The whitespace and new line is intended! */
  // Foobar !!!
  [class X   extends /****/ Error
  // More comments
  {}, '[class X extends Error]'],
  /* eslint-enable spaced-comment, no-multi-spaces, brace-style */
].forEach(([clazz, string]) => {
  const inspected = util.inspect(clazz);
  assert.strictEqual(inspected, string);
  Object.defineProperty(clazz, Symbol.toStringTag, {
    value: 'Woohoo'
  });
  const parts = inspected.slice(0, -1).split(' ');
  const [, name, ...rest] = parts;
  rest.unshift('[Woohoo]');
  if (rest.length) {
    rest[rest.length - 1] += ']';
  }
  assert.strictEqual(
    util.inspect(clazz),
    ['[class', name, ...rest].join(' ')
  );
  if (rest.length) {
    rest[rest.length - 1] = rest[rest.length - 1].slice(0, -1);
    rest.length = 1;
  }
  Object.setPrototypeOf(clazz, Map.prototype);
  assert.strictEqual(
    util.inspect(clazz),
    ['[class', name, '[Map]', ...rest].join(' ') + ']'
  );
  Object.setPrototypeOf(clazz, null);
  assert.strictEqual(
    util.inspect(clazz),
    ['[class', name, ...rest, 'extends [null prototype]]'].join(' ')
  );
  Object.defineProperty(clazz, 'name', { value: 'Foo' });
  const res = ['[class', 'Foo', ...rest, 'extends [null prototype]]'].join(' ');
  assert.strictEqual(util.inspect(clazz), res);
  clazz.foo = true;
  assert.strictEqual(util.inspect(clazz), `${res} { foo: true }`);
});

// "class" properties should not be detected as "class".
{
  // eslint-disable-next-line space-before-function-paren
  let obj = { class () {} };
  assert.strictEqual(
    util.inspect(obj),
    '{ class: [Function: class] }'
  );
  obj = { class: () => {} };
  assert.strictEqual(
    util.inspect(obj),
    '{ class: [Function: class] }'
  );
  obj = { ['class Foo {}']() {} };
  assert.strictEqual(
    util.inspect(obj),
    "{ 'class Foo {}': [Function: class Foo {}] }"
  );
  function Foo() {}
  Object.defineProperty(Foo, 'toString', { value: () => 'class Foo {}' });
  assert.strictEqual(
    util.inspect(Foo),
    '[Function: Foo]'
  );
  function fn() {}
  Object.defineProperty(fn, 'name', { value: 'class Foo {}' });
  assert.strictEqual(
    util.inspect(fn),
    '[Function: class Foo {}]'
  );
}

// Verify that throwing in valueOf and toString still produces nice results.
[
  [new String(55), "[String: '55']"],
  [new Boolean(true), '[Boolean: true]'],
  [new Number(55), '[Number: 55]'],
  [Object(BigInt(55)), '[BigInt: 55n]'],
  [Object(Symbol('foo')), '[Symbol: Symbol(foo)]'],
  [function() {}, '[Function (anonymous)]'],
  [() => {}, '[Function (anonymous)]'],
  [[1, 2], '[ 1, 2 ]'],
  // eslint-disable-next-line no-sparse-arrays
  [[, , 5, , , , ], '[ <2 empty items>, 5, <3 empty items> ]'],
  [{ a: 5 }, '{ a: 5 }'],
  [new Set([1, 2]), 'Set(2) { 1, 2 }'],
  [new Map([[1, 2]]), 'Map(1) { 1 => 2 }'],
  [new Set([1, 2]).entries(), '[Set Entries] { [ 1, 1 ], [ 2, 2 ] }'],
  [new Map([[1, 2]]).keys(), '[Map Iterator] { 1 }'],
  [new Date(2000), '1970-01-01T00:00:02.000Z'],
  [new Uint8Array(2), 'Uint8Array(2) [ 0, 0 ]'],
  [new Promise((resolve) => setTimeout(resolve, 10)), 'Promise { <pending> }'],
  [new WeakSet(), 'WeakSet { <items unknown> }'],
  [new WeakMap(), 'WeakMap { <items unknown> }'],
  [/foobar/g, '/foobar/g'],
].forEach(([value, expected]) => {
  Object.defineProperty(value, 'valueOf', {
    get() {
      throw new Error('valueOf');
    }
  });
  Object.defineProperty(value, 'toString', {
    get() {
      throw new Error('toString');
    }
  });
  assert.strictEqual(util.inspect(value), expected);
  value.foo = 'bar';
  assert.notStrictEqual(util.inspect(value), expected);
  delete value.foo;
  value[Symbol('foo')] = 'yeah';
  assert.notStrictEqual(util.inspect(value), expected);
});

// Verify that having no prototype still produces nice results.
[
  [[1, 3, 4], '[Array(3): null prototype] [ 1, 3, 4 ]'],
  [new Set([1, 2]), '[Set(2): null prototype] { 1, 2 }'],
  [new Map([[1, 2]]), '[Map(1): null prototype] { 1 => 2 }'],
  [new Promise((resolve) => setTimeout(resolve, 10)),
   '[Promise: null prototype] { <pending> }'],
  [new WeakSet(), '[WeakSet: null prototype] { <items unknown> }'],
  [new WeakMap(), '[WeakMap: null prototype] { <items unknown> }'],
  [new Uint8Array(2), '[Uint8Array(2): null prototype] [ 0, 0 ]'],
  [new Uint16Array(2), '[Uint16Array(2): null prototype] [ 0, 0 ]'],
  [new Uint32Array(2), '[Uint32Array(2): null prototype] [ 0, 0 ]'],
  [new Int8Array(2), '[Int8Array(2): null prototype] [ 0, 0 ]'],
  [new Int16Array(2), '[Int16Array(2): null prototype] [ 0, 0 ]'],
  [new Int32Array(2), '[Int32Array(2): null prototype] [ 0, 0 ]'],
  [new Float32Array(2), '[Float32Array(2): null prototype] [ 0, 0 ]'],
  [new Float64Array(2), '[Float64Array(2): null prototype] [ 0, 0 ]'],
  [new BigInt64Array(2), '[BigInt64Array(2): null prototype] [ 0n, 0n ]'],
  [new BigUint64Array(2), '[BigUint64Array(2): null prototype] [ 0n, 0n ]'],
  [new ArrayBuffer(16), '[ArrayBuffer: null prototype] {\n' +
     '  [Uint8Contents]: <00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00>,\n' +
     '  byteLength: undefined\n}'],
  [new DataView(new ArrayBuffer(16)),
   '[DataView: null prototype] {\n  byteLength: undefined,\n  ' +
     'byteOffset: undefined,\n  buffer: undefined\n}'],
  [new SharedArrayBuffer(2), '[SharedArrayBuffer: null prototype] ' +
     '{\n  [Uint8Contents]: <00 00>,\n  byteLength: undefined\n}'],
  [/foobar/, '[RegExp: null prototype] /foobar/'],
  [new Date('Sun, 14 Feb 2010 11:48:40 GMT'),
   '[Date: null prototype] 2010-02-14T11:48:40.000Z'],
].forEach(([value, expected]) => {
  assert.strictEqual(
    util.inspect(Object.setPrototypeOf(value, null)),
    expected
  );
  value.foo = 'bar';
  assert.notStrictEqual(util.inspect(value), expected);
  delete value.foo;
  value[Symbol('foo')] = 'yeah';
  assert.notStrictEqual(util.inspect(value), expected);
});

// Verify that subclasses with and without prototype produce nice results.
[
  [RegExp, ['foobar', 'g'], '/foobar/g'],
  [WeakSet, [[{}]], '{ <items unknown> }'],
  [WeakMap, [[[{}, {}]]], '{ <items unknown> }'],
  [BigInt64Array,
   [10],
   '[\n  0n, 0n, 0n, 0n, 0n,\n  0n, 0n, 0n, 0n, 0n\n]'],
  [Date, ['Sun, 14 Feb 2010 11:48:40 GMT'], '2010-02-14T11:48:40.000Z'],
  [Date, ['invalid_date'], 'Invalid Date'],
].forEach(([base, input, rawExpected]) => {
  class Foo extends base {}
  const value = new Foo(...input);
  const symbol = value[Symbol.toStringTag];
  const size = base.name.includes('Array') ? `(${input[0]})` : '';
  const expected = `Foo${size} ${symbol ? `[${symbol}] ` : ''}${rawExpected}`;
  const expectedWithoutProto =
    `[${base.name}${size}: null prototype] ${rawExpected}`;
  assert.strictEqual(util.inspect(value), expected);
  value.foo = 'bar';
  assert.notStrictEqual(util.inspect(value), expected);
  delete value.foo;
  assert.strictEqual(
    util.inspect(Object.setPrototypeOf(value, null)),
    expectedWithoutProto
  );
  value.foo = 'bar';
  let res = util.inspect(value);
  assert.notStrictEqual(res, expectedWithoutProto);
  assert.match(res, /foo: 'bar'/);
  delete value.foo;
  value[Symbol('foo')] = 'yeah';
  res = util.inspect(value);
  assert.notStrictEqual(res, expectedWithoutProto);
  assert.match(res, /\[Symbol\(foo\)]: 'yeah'/);
});

assert.strictEqual(inspect(1n), '1n');
assert.strictEqual(inspect(Object(-1n)), '[BigInt: -1n]');
assert.strictEqual(inspect(Object(13n)), '[BigInt: 13n]');
assert.strictEqual(inspect(new BigInt64Array([0n])), 'BigInt64Array(1) [ 0n ]');
assert.strictEqual(
  inspect(new BigUint64Array([0n])), 'BigUint64Array(1) [ 0n ]');

// Verify non-enumerable keys get escaped.
{
  const obj = {};
  Object.defineProperty(obj, 'Non\nenumerable\tkey', { value: true });
  assert.strictEqual(
    util.inspect(obj, { showHidden: true }),
    '{ [Non\\nenumerable\\tkey]: true }'
  );
}

// Check for special colors.
{
  const special = inspect.colors[inspect.styles.special];
  const string = inspect.colors[inspect.styles.string];

  assert.strictEqual(
    inspect(new WeakSet(), { colors: true }),
    `WeakSet { \u001b[${special[0]}m<items unknown>\u001b[${special[1]}m }`
  );
  assert.strictEqual(
    inspect(new WeakMap(), { colors: true }),
    `WeakMap { \u001b[${special[0]}m<items unknown>\u001b[${special[1]}m }`
  );
  assert.strictEqual(
    inspect(new Promise(() => {}), { colors: true }),
    `Promise { \u001b[${special[0]}m<pending>\u001b[${special[1]}m }`
  );

  const rejection = Promise.reject('Oh no!');
  assert.strictEqual(
    inspect(rejection, { colors: true }),
    `Promise { \u001b[${special[0]}m<rejected>\u001b[${special[1]}m ` +
    `\u001b[${string[0]}m'Oh no!'\u001b[${string[1]}m }`
  );
  rejection.catch(() => {});

  // Verify that aliases do not show up as key while checking `inspect.colors`.
  const colors = Object.keys(inspect.colors);
  const aliases = Object.getOwnPropertyNames(inspect.colors)
                  .filter((c) => !colors.includes(c));
  assert(!colors.includes('grey'));
  assert(colors.includes('gray'));
  // Verify that all aliases are correctly mapped.
  for (const alias of aliases) {
    assert(Array.isArray(inspect.colors[alias]));
  }
  // Check consistent naming.
  [
    'black',
    'red',
    'green',
    'yellow',
    'blue',
    'magenta',
    'cyan',
    'white',
  ].forEach((color, i) => {
    assert.deepStrictEqual(inspect.colors[color], [30 + i, 39]);
    assert.deepStrictEqual(inspect.colors[`${color}Bright`], [90 + i, 39]);
    const bgColor = `bg${color[0].toUpperCase()}${color.slice(1)}`;
    assert.deepStrictEqual(inspect.colors[bgColor], [40 + i, 49]);
    assert.deepStrictEqual(inspect.colors[`${bgColor}Bright`], [100 + i, 49]);
  });

  // Unknown colors are handled gracefully:
  const stringStyle = inspect.styles.string;
  inspect.styles.string = 'UNKNOWN';
  assert.strictEqual(inspect('foobar', { colors: true }), "'foobar'");
  inspect.styles.string = stringStyle;
}

assert.strictEqual(
  inspect([1, 3, 2], { sorted: true }),
  inspect([1, 3, 2])
);
assert.strictEqual(
  inspect({ c: 3, a: 1, b: 2 }, { sorted: true }),
  '{ a: 1, b: 2, c: 3 }'
);
assert.strictEqual(
  inspect(
    { a200: 4, a100: 1, a102: 3, a101: 2 },
    { sorted(a, b) { return b.localeCompare(a); } }
  ),
  '{ a200: 4, a102: 3, a101: 2, a100: 1 }'
);

// Non-indices array properties are sorted as well.
{
  const arr = [3, 2, 1];
  arr.b = 2;
  arr.c = 3;
  arr.a = 1;
  arr[Symbol('b')] = true;
  arr[Symbol('a')] = false;
  assert.strictEqual(
    inspect(arr, { sorted: true }),
    '[ 3, 2, 1, [Symbol(a)]: false, [Symbol(b)]: true, a: 1, b: 2, c: 3 ]'
  );
}

// Manipulate the prototype in weird ways.
{
  let obj = { a: true };
  let value = (function() { return function() {}; })();
  Object.setPrototypeOf(value, null);
  Object.setPrototypeOf(obj, value);
  assert.strictEqual(
    util.inspect(obj),
    'Object <[Function (null prototype) (anonymous)]> { a: true }'
  );
  assert.strictEqual(
    util.inspect(obj, { colors: true }),
    'Object <\u001b[36m[Function (null prototype) (anonymous)]\u001b[39m> ' +
      '{ a: \u001b[33mtrue\u001b[39m }'
  );

  obj = { a: true };
  value = [];
  Object.setPrototypeOf(value, null);
  Object.setPrototypeOf(obj, value);
  assert.strictEqual(
    util.inspect(obj),
    'Object <[Array(0): null prototype] []> { a: true }'
  );

  function StorageObject() {}
  StorageObject.prototype = Object.create(null);
  assert.strictEqual(
    util.inspect(new StorageObject()),
    'StorageObject <[Object: null prototype] {}> {}'
  );

  obj = [1, 2, 3];
  Object.setPrototypeOf(obj, Number.prototype);
  assert.strictEqual(inspect(obj), "Number { '0': 1, '1': 2, '2': 3 }");

  Object.setPrototypeOf(obj, Object.create(null));
  assert.strictEqual(
    inspect(obj),
    "Array <[Object: null prototype] {}> { '0': 1, '1': 2, '2': 3 }"
  );

  StorageObject.prototype = Object.create(null);
  Object.setPrototypeOf(StorageObject.prototype, Object.create(null));
  Object.setPrototypeOf(
    Object.getPrototypeOf(StorageObject.prototype),
    Object.create(null)
  );
  assert.strictEqual(
    util.inspect(new StorageObject()),
    'StorageObject <Object <Object <[Object: null prototype] {}>>> {}'
  );
  assert.strictEqual(
    util.inspect(new StorageObject(), { depth: 1 }),
    'StorageObject <Object <Object <Complex prototype>>> {}'
  );
}

// Check that the fallback always works.
{
  const obj = new Set([1, 2]);
  const iterator = obj[Symbol.iterator];
  Object.setPrototypeOf(obj, null);
  Object.defineProperty(obj, Symbol.iterator, {
    value: iterator,
    configurable: true
  });
  assert.strictEqual(util.inspect(obj), '[Set(2): null prototype] { 1, 2 }');
  Object.defineProperty(obj, Symbol.iterator, {
    value: true,
    configurable: true
  });
  Object.defineProperty(obj, 'size', {
    value: NaN,
    configurable: true,
    enumerable: true
  });
  assert.strictEqual(
    util.inspect(obj),
    '[Set(2): null prototype] { 1, 2, size: NaN }'
  );
}

// Check the getter option.
{
  let foo = 1;
  const get = { get foo() { return foo; } };
  const getset = {
    get foo() { return foo; },
    set foo(val) { foo = val; },
    get inc() { return ++foo; }
  };
  const thrower = { get foo() { throw new Error('Oops'); } };
  assert.strictEqual(
    inspect(get, { getters: true, colors: true }),
    '{ foo: \u001b[36m[Getter:\u001b[39m ' +
      '\u001b[33m1\u001b[39m\u001b[36m]\u001b[39m }');
  assert.strictEqual(
    inspect(thrower, { getters: true }),
    '{ foo: [Getter: <Inspection threw (Oops)>] }');
  assert.strictEqual(
    inspect(getset, { getters: true }),
    '{ foo: [Getter/Setter: 1], inc: [Getter: 2] }');
  assert.strictEqual(
    inspect(getset, { getters: 'get' }),
    '{ foo: [Getter/Setter], inc: [Getter: 3] }');
  assert.strictEqual(
    inspect(getset, { getters: 'set' }),
    '{ foo: [Getter/Setter: 3], inc: [Getter] }');
  getset.foo = new Set([[{ a: true }, 2, {}], 'foobar', { x: 1 }]);
  assert.strictEqual(
    inspect(getset, { getters: true }),
    '{\n  foo: [Getter/Setter] Set(3) { [ [Object], 2, {} ], ' +
      "'foobar', { x: 1 } },\n  inc: [Getter: NaN]\n}");
}

// Check compact number mode.
{
  let obj = {
    a: {
      b: {
        x: 5,
        c: {
          x: '10000000000000000 00000000000000000 '.repeat(1e1),
          d: 2,
          e: 3
        }
      }
    },
    b: [
      1,
      2,
      [ 1, 2, { a: 1, b: 2, c: 3 } ],
    ],
    c: ['foo', 4, 444444],
    d: Array.from({ length: 101 }).map((e, i) => {
      return i % 2 === 0 ? i * i : i;
    }),
    e: Array(6).fill('foobar'),
    f: Array(9).fill('foobar'),
    g: Array(21).fill('foobar baz'),
    h: [100].concat(Array.from({ length: 9 }).map((e, n) => (n))),
    long: Array(9).fill('This text is too long for grouping!')
  };

  let out = util.inspect(obj, { compact: 3, depth: 10, breakLength: 60 });
  let expected = [
    '{',
    '  a: {',
    '    b: {',
    '      x: 5,',
    '      c: {',
    "        x: '10000000000000000 00000000000000000 10000000000000000 " +
      '00000000000000000 10000000000000000 00000000000000000 ' +
      '10000000000000000 00000000000000000 10000000000000000 ' +
      '00000000000000000 10000000000000000 00000000000000000 ' +
      '10000000000000000 00000000000000000 10000000000000000 ' +
      '00000000000000000 10000000000000000 00000000000000000 ' +
      "10000000000000000 00000000000000000 ',",
    '        d: 2,',
    '        e: 3',
    '      }',
    '    }',
    '  },',
    '  b: [ 1, 2, [ 1, 2, { a: 1, b: 2, c: 3 } ] ],',
    "  c: [ 'foo', 4, 444444 ],",
    '  d: [',
    '       0,    1,    4,    3,   16,    5,   36,    7,   64,',
    '       9,  100,   11,  144,   13,  196,   15,  256,   17,',
    '     324,   19,  400,   21,  484,   23,  576,   25,  676,',
    '      27,  784,   29,  900,   31, 1024,   33, 1156,   35,',
    '    1296,   37, 1444,   39, 1600,   41, 1764,   43, 1936,',
    '      45, 2116,   47, 2304,   49, 2500,   51, 2704,   53,',
    '    2916,   55, 3136,   57, 3364,   59, 3600,   61, 3844,',
    '      63, 4096,   65, 4356,   67, 4624,   69, 4900,   71,',
    '    5184,   73, 5476,   75, 5776,   77, 6084,   79, 6400,',
    '      81, 6724,   83, 7056,   85, 7396,   87, 7744,   89,',
    '    8100,   91, 8464,   93, 8836,   95, 9216,   97, 9604,',
    '      99,',
    '    ... 1 more item',
    '  ],',
    '  e: [',
    "    'foobar',",
    "    'foobar',",
    "    'foobar',",
    "    'foobar',",
    "    'foobar',",
    "    'foobar'",
    '  ],',
    '  f: [',
    "    'foobar', 'foobar',",
    "    'foobar', 'foobar',",
    "    'foobar', 'foobar',",
    "    'foobar', 'foobar',",
    "    'foobar'",
    '  ],',
    '  g: [',
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz', 'foobar baz',",
    "    'foobar baz'",
    '  ],',
    '  h: [',
    '    100, 0, 1, 2, 3,',
    '      4, 5, 6, 7, 8',
    '  ],',
    '  long: [',
    "    'This text is too long for grouping!',",
    "    'This text is too long for grouping!',",
    "    'This text is too long for grouping!',",
    "    'This text is too long for grouping!',",
    "    'This text is too long for grouping!',",
    "    'This text is too long for grouping!',",
    "    'This text is too long for grouping!',",
    "    'This text is too long for grouping!',",
    "    'This text is too long for grouping!'",
    '  ]',
    '}',
  ].join('\n');

  assert.strictEqual(out, expected);

  obj = [
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 123456789,
  ];

  out = util.inspect(obj, { compact: 3 });

  expected = [
    '[',
    '  1, 1,         1, 1,',
    '  1, 1,         1, 1,',
    '  1, 1,         1, 1,',
    '  1, 1,         1, 1,',
    '  1, 1,         1, 1,',
    '  1, 1,         1, 1,',
    '  1, 1, 123456789',
    ']',
  ].join('\n');

  assert.strictEqual(out, expected);

  // Unicode support. あ has a length of one and a width of two.
  obj = [
    '123', '123', '123', '123', 'あああ',
    '123', '123', '123', '123', 'あああ',
  ];

  out = util.inspect(obj, { compact: 3 });

  expected = [
    '[',
    "  '123',    '123',",
    "  '123',    '123',",
    "  'あああ', '123',",
    "  '123',    '123',",
    "  '123',    'あああ'",
    ']',
  ].join('\n');

  assert.strictEqual(out, expected);

  // Array grouping should prevent lining up outer elements on a single line.
  obj = [[[1, 2, 3, 4, 5, 6, 7, 8, 9]]];

  out = util.inspect(obj, { compact: 3 });

  expected = [
    '[',
    '  [',
    '    [',
    '      1, 2, 3, 4, 5,',
    '      6, 7, 8, 9',
    '    ]',
    '  ]',
    ']',
  ].join('\n');

  assert.strictEqual(out, expected);

  // Verify that array grouping and line consolidation does not happen together.
  obj = {
    a: {
      b: {
        x: 5,
        c: {
          d: 2,
          e: 3
        }
      }
    },
    b: Array.from({ length: 9 }).map((e, n) => {
      return n % 2 === 0 ? 'foobar' : 'baz';
    })
  };

  out = util.inspect(obj, { compact: 1, breakLength: Infinity, colors: true });

  expected = [
    '{',
    '  a: {',
    '    b: { x: \u001b[33m5\u001b[39m, c: \u001b[36m[Object]\u001b[39m }',
    '  },',
    '  b: [',
    "    \u001b[32m'foobar'\u001b[39m, \u001b[32m'baz'\u001b[39m,",
    "    \u001b[32m'foobar'\u001b[39m, \u001b[32m'baz'\u001b[39m,",
    "    \u001b[32m'foobar'\u001b[39m, \u001b[32m'baz'\u001b[39m,",
    "    \u001b[32m'foobar'\u001b[39m, \u001b[32m'baz'\u001b[39m,",
    "    \u001b[32m'foobar'\u001b[39m",
    '  ]',
    '}',
  ].join('\n');

  assert.strictEqual(out, expected);

  obj = Array.from({ length: 60 }).map((e, i) => i);
  out = util.inspect(obj, { compact: 1, breakLength: Infinity, colors: true });

  expected = [
    '[',
    /* eslint-disable max-len */
    '   \u001b[33m0\u001b[39m,  \u001b[33m1\u001b[39m,  \u001b[33m2\u001b[39m,  \u001b[33m3\u001b[39m,',
    '   \u001b[33m4\u001b[39m,  \u001b[33m5\u001b[39m,  \u001b[33m6\u001b[39m,  \u001b[33m7\u001b[39m,',
    '   \u001b[33m8\u001b[39m,  \u001b[33m9\u001b[39m, \u001b[33m10\u001b[39m, \u001b[33m11\u001b[39m,',
    '  \u001b[33m12\u001b[39m, \u001b[33m13\u001b[39m, \u001b[33m14\u001b[39m, \u001b[33m15\u001b[39m,',
    '  \u001b[33m16\u001b[39m, \u001b[33m17\u001b[39m, \u001b[33m18\u001b[39m, \u001b[33m19\u001b[39m,',
    '  \u001b[33m20\u001b[39m, \u001b[33m21\u001b[39m, \u001b[33m22\u001b[39m, \u001b[33m23\u001b[39m,',
    '  \u001b[33m24\u001b[39m, \u001b[33m25\u001b[39m, \u001b[33m26\u001b[39m, \u001b[33m27\u001b[39m,',
    '  \u001b[33m28\u001b[39m, \u001b[33m29\u001b[39m, \u001b[33m30\u001b[39m, \u001b[33m31\u001b[39m,',
    '  \u001b[33m32\u001b[39m, \u001b[33m33\u001b[39m, \u001b[33m34\u001b[39m, \u001b[33m35\u001b[39m,',
    '  \u001b[33m36\u001b[39m, \u001b[33m37\u001b[39m, \u001b[33m38\u001b[39m, \u001b[33m39\u001b[39m,',
    '  \u001b[33m40\u001b[39m, \u001b[33m41\u001b[39m, \u001b[33m42\u001b[39m, \u001b[33m43\u001b[39m,',
    '  \u001b[33m44\u001b[39m, \u001b[33m45\u001b[39m, \u001b[33m46\u001b[39m, \u001b[33m47\u001b[39m,',
    '  \u001b[33m48\u001b[39m, \u001b[33m49\u001b[39m, \u001b[33m50\u001b[39m, \u001b[33m51\u001b[39m,',
    '  \u001b[33m52\u001b[39m, \u001b[33m53\u001b[39m, \u001b[33m54\u001b[39m, \u001b[33m55\u001b[39m,',
    '  \u001b[33m56\u001b[39m, \u001b[33m57\u001b[39m, \u001b[33m58\u001b[39m, \u001b[33m59\u001b[39m',
    /* eslint-enable max-len */
    ']',
  ].join('\n');

  assert.strictEqual(out, expected);

  out = util.inspect([1, 2, 3, 4], { compact: 1, colors: true });
  expected = '[ \u001b[33m1\u001b[39m, \u001b[33m2\u001b[39m, ' +
    '\u001b[33m3\u001b[39m, \u001b[33m4\u001b[39m ]';

  assert.strictEqual(out, expected);

  obj = [
    'Object', 'Function', 'Array',
    'Number', 'parseFloat', 'parseInt',
    'Infinity', 'NaN', 'undefined',
    'Boolean', 'String', 'Symbol',
    'Date', 'Promise', 'RegExp',
    'Error', 'EvalError', 'RangeError',
    'ReferenceError', 'SyntaxError', 'TypeError',
    'URIError', 'JSON', 'Math',
    'console', 'Intl', 'ArrayBuffer',
    'Uint8Array', 'Int8Array', 'Uint16Array',
    'Int16Array', 'Uint32Array', 'Int32Array',
    'Float32Array', 'Float64Array', 'Uint8ClampedArray',
    'BigUint64Array', 'BigInt64Array', 'DataView',
    'Map', 'BigInt', 'Set',
    'WeakMap', 'WeakSet', 'Proxy',
    'Reflect', 'decodeURI', 'decodeURIComponent',
    'encodeURI', 'encodeURIComponent', 'escape',
    'unescape', 'eval', 'isFinite',
    'isNaN', 'SharedArrayBuffer', 'Atomics',
    'globalThis', 'WebAssembly', 'global',
    'process', 'Buffer', 'URL',
    'URLSearchParams', 'TextEncoder', 'TextDecoder',
    'clearInterval', 'clearTimeout', 'setInterval',
    'setTimeout', 'queueMicrotask', 'clearImmediate',
    'setImmediate', 'module', 'require',
    'assert', 'async_hooks', 'buffer',
    'child_process', 'cluster', 'crypto',
    'dgram', 'dns', 'domain',
    'events', 'fs', 'http',
    'http2', 'https', 'inspector',
    'net', 'os', 'path',
    'perf_hooks', 'punycode', 'querystring',
    'readline', 'repl', 'stream',
    'string_decoder', 'tls', 'trace_events',
    'tty', 'url', 'v8',
    'vm', 'worker_threads', 'zlib',
    '_', '_error', 'util',
  ];

  out = util.inspect(
    obj,
    { compact: 3, breakLength: 80, maxArrayLength: 250 }
  );
  expected = [
    '[',
    "  'Object',          'Function',           'Array',",
    "  'Number',          'parseFloat',         'parseInt',",
    "  'Infinity',        'NaN',                'undefined',",
    "  'Boolean',         'String',             'Symbol',",
    "  'Date',            'Promise',            'RegExp',",
    "  'Error',           'EvalError',          'RangeError',",
    "  'ReferenceError',  'SyntaxError',        'TypeError',",
    "  'URIError',        'JSON',               'Math',",
    "  'console',         'Intl',               'ArrayBuffer',",
    "  'Uint8Array',      'Int8Array',          'Uint16Array',",
    "  'Int16Array',      'Uint32Array',        'Int32Array',",
    "  'Float32Array',    'Float64Array',       'Uint8ClampedArray',",
    "  'BigUint64Array',  'BigInt64Array',      'DataView',",
    "  'Map',             'BigInt',             'Set',",
    "  'WeakMap',         'WeakSet',            'Proxy',",
    "  'Reflect',         'decodeURI',          'decodeURIComponent',",
    "  'encodeURI',       'encodeURIComponent', 'escape',",
    "  'unescape',        'eval',               'isFinite',",
    "  'isNaN',           'SharedArrayBuffer',  'Atomics',",
    "  'globalThis',      'WebAssembly',        'global',",
    "  'process',         'Buffer',             'URL',",
    "  'URLSearchParams', 'TextEncoder',        'TextDecoder',",
    "  'clearInterval',   'clearTimeout',       'setInterval',",
    "  'setTimeout',      'queueMicrotask',     'clearImmediate',",
    "  'setImmediate',    'module',             'require',",
    "  'assert',          'async_hooks',        'buffer',",
    "  'child_process',   'cluster',            'crypto',",
    "  'dgram',           'dns',                'domain',",
    "  'events',          'fs',                 'http',",
    "  'http2',           'https',              'inspector',",
    "  'net',             'os',                 'path',",
    "  'perf_hooks',      'punycode',           'querystring',",
    "  'readline',        'repl',               'stream',",
    "  'string_decoder',  'tls',                'trace_events',",
    "  'tty',             'url',                'v8',",
    "  'vm',              'worker_threads',     'zlib',",
    "  '_',               '_error',             'util'",
    ']',
  ].join('\n');

  assert.strictEqual(out, expected);
}

{
  // Use a fake stack to verify the expected colored outcome.
  const stack = [
    'TypedError: Wonderful message!',
    '    at A.<anonymous> (/test/node_modules/foo/node_modules/bar/baz.js:2:7)',
    '    at Module._compile (node:internal/modules/cjs/loader:827:30)',
    '    at Fancy (node:vm:697:32)',
    // This file is not an actual Node.js core file.
    '    at tryModuleLoad (node:internal/modules/cjs/foo:629:12)',
    '    at Function.Module._load (node:internal/modules/cjs/loader:621:3)',
    // This file is not an actual Node.js core file.
    '    at Module.require [as weird/name] (node:internal/aaaaa/loader:735:19)',
    '    at require (node:internal/modules/cjs/helpers:14:16)',
    '    at /test/test-util-inspect.js:2239:9',
    '    at getActual (node:assert:592:5)',
  ];
  const isNodeCoreFile = [
    false, false, true, true, false, true, false, true, false, true,
  ];
  const err = new TypeError('Wonderful message!');
  err.stack = stack.join('\n');
  util.inspect(err, { colors: true }).split('\n').forEach((line, i) => {
    let actual = stack[i].replace(/node_modules\/([a-z]+)/g, (a, m) => {
      return `node_modules/\u001b[4m${m}\u001b[24m`;
    });
    if (isNodeCoreFile[i]) {
      actual = `\u001b[90m${actual}\u001b[39m`;
    }
    assert.strictEqual(actual, line);
  });
}

{
  // Cross platform checks.
  const err = new Error('foo');
  util.inspect(err, { colors: true }).split('\n').forEach((line, i) => {
    assert(i < 2 || line.startsWith('\u001b[90m'));
  });
}

{
  // Tracing class respects inspect depth.
  try {
    const trace = require('trace_events').createTracing({ categories: ['fo'] });
    const actualDepth0 = util.inspect({ trace }, { depth: 0 });
    assert.strictEqual(actualDepth0, '{ trace: [Tracing] }');
    const actualDepth1 = util.inspect({ trace }, { depth: 1 });
    assert.strictEqual(
      actualDepth1,
      "{ trace: Tracing { enabled: false, categories: 'fo' } }"
    );
  } catch (err) {
    if (err.code !== 'ERR_TRACE_EVENTS_UNAVAILABLE')
      throw err;
  }
}

// Inspect prototype properties.
{
  class Foo extends Map {
    prop = false;
    prop2 = true;
    get abc() {
      return true;
    }
    get def() {
      return false;
    }
    set def(v) {}
    get xyz() {
      return 'Should be ignored';
    }
    func(a) {}
    [util.inspect.custom]() {
      return this;
    }
  }

  class Bar extends Foo {
    abc = true;
    prop = true;
    get xyz() {
      return 'YES!';
    }
    [util.inspect.custom]() {
      return this;
    }
  }

  const bar = new Bar();

  assert.strictEqual(
    inspect(bar),
    'Bar(0) [Map] { prop: true, prop2: true, abc: true }'
  );
  assert.strictEqual(
    inspect(bar, { showHidden: true, getters: true, colors: false }),
    'Bar(0) [Map] {\n' +
    '  prop: true,\n' +
    '  prop2: true,\n' +
    '  abc: true,\n' +
    "  [xyz]: [Getter: 'YES!'],\n" +
    '  [def]: [Getter/Setter: false]\n' +
    '}'
  );
  assert.strictEqual(
    inspect(bar, { showHidden: true, getters: false, colors: true }),
    'Bar(0) [Map] {\n' +
    '  prop: \x1B[33mtrue\x1B[39m,\n' +
    '  prop2: \x1B[33mtrue\x1B[39m,\n' +
    '  abc: \x1B[33mtrue\x1B[39m,\n' +
    '  \x1B[2m[xyz]: \x1B[36m[Getter]\x1B[39m\x1B[22m,\n' +
    '  \x1B[2m[def]: \x1B[36m[Getter/Setter]\x1B[39m\x1B[22m\n' +
    '}'
  );

  const obj = Object.create({ abc: true, def: 5, toString() {} });
  assert.strictEqual(
    inspect(obj, { showHidden: true, colors: true }),
    '{ \x1B[2mabc: \x1B[33mtrue\x1B[39m\x1B[22m, ' +
      '\x1B[2mdef: \x1B[33m5\x1B[39m\x1B[22m }'
  );

  assert.strictEqual(
    inspect(Object.getPrototypeOf(bar), { showHidden: true, getters: true }),
    '<ref *1> Foo [Map] {\n' +
    '    [constructor]: [class Bar extends Foo] {\n' +
    '      [length]: 0,\n' +
    "      [name]: 'Bar',\n" +
    '      [prototype]: [Circular *1],\n' +
    '      [Symbol(Symbol.species)]: [Getter: <Inspection threw ' +
      "(Symbol.prototype.toString requires that 'this' be a Symbol)>]\n" +
    '    },\n' +
    "    [xyz]: [Getter: 'YES!'],\n" +
    '    [Symbol(nodejs.util.inspect.custom)]: ' +
      '[Function: [nodejs.util.inspect.custom]] {\n' +
    '      [length]: 0,\n' +
    "      [name]: '[nodejs.util.inspect.custom]'\n" +
    '    },\n' +
    '    [abc]: [Getter: true],\n' +
    '    [def]: [Getter/Setter: false]\n' +
    '  }'
  );

  assert.strictEqual(
    inspect(Object.getPrototypeOf(bar)),
    'Foo [Map] {}'
  );

  assert.strictEqual(
    inspect(Object.getPrototypeOf(new Foo())),
    'Map {}'
  );
}

// Check that prototypes with a null prototype are inspectable.
// Regression test for https://github.com/nodejs/node/issues/35730
{
  function Func() {}
  Func.prototype = null;
  const object = {};
  object.constructor = Func;

  assert.strictEqual(util.inspect(object), '{ constructor: [Function: Func] }');
}

// Test changing util.inspect.colors colors and aliases.
{
  const colors = util.inspect.colors;

  const originalValue = colors.gray;

  // "grey" is reference-equal alias of "gray".
  assert.strictEqual(colors.grey, colors.gray);

  // Assigninging one should assign the other. This tests that the alias setter
  // function keeps things reference-equal.
  colors.gray = [0, 0];
  assert.deepStrictEqual(colors.gray, [0, 0]);
  assert.strictEqual(colors.grey, colors.gray);

  colors.grey = [1, 1];
  assert.deepStrictEqual(colors.grey, [1, 1]);
  assert.strictEqual(colors.grey, colors.gray);

  // Restore original value to avoid side effects in other tests.
  colors.gray = originalValue;
  assert.deepStrictEqual(colors.gray, originalValue);
  assert.strictEqual(colors.grey, colors.gray);
}

// https://github.com/nodejs/node/issues/31889
{
  v8.setFlagsFromString('--allow-natives-syntax');
  const undetectable = vm.runInThisContext('%GetUndetectable()');
  v8.setFlagsFromString('--no-allow-natives-syntax');
  assert.strictEqual(inspect(undetectable), '{}');
}

// Truncate output for Primitives with 1 character left
{
  assert.strictEqual(util.inspect('bl', { maxStringLength: 1 }),
                     "'b'... 1 more character");
}

{
  const x = 'a'.repeat(1e6);
  assert(util.inspect(x).endsWith('... 990000 more characters'));
  assert.strictEqual(
    util.inspect(x, { maxStringLength: 4 }),
    "'aaaa'... 999996 more characters"
  );
  assert.match(util.inspect(x, { maxStringLength: null }), /a'$/);
}

{
  // Verify that util.inspect() invokes custom inspect functions on objects
  // from other vm.Contexts but does not pass data from its own Context to that
  // function.
  const target = vm.runInNewContext(`
    ({
      [Symbol.for('nodejs.util.inspect.custom')](depth, ctx) {
        this.depth = depth;
        this.ctx = ctx;
        try {
          this.stylized = ctx.stylize('🐈');
        } catch (e) {
          this.stylizeException = e;
        }
        return this.stylized;
      }
    })
  `, Object.create(null));
  assert.strictEqual(target.ctx, undefined);

  {
    // Subtest 1: Just try to inspect the object with default options.
    assert.strictEqual(util.inspect(target), '🐈');
    assert.strictEqual(typeof target.ctx, 'object');
    const objectGraph = fullObjectGraph(target);
    assert(!objectGraph.has(Object));
    assert(!objectGraph.has(Function));
  }

  {
    // Subtest 2: Use a stylize function that returns a non-primitive.
    const output = util.inspect(target, {
      stylize: common.mustCall((str) => {
        return {};
      })
    });
    assert.strictEqual(output, '[object Object]');
    assert.strictEqual(typeof target.ctx, 'object');
    const objectGraph = fullObjectGraph(target);
    assert(!objectGraph.has(Object));
    assert(!objectGraph.has(Function));
  }

  {
    // Subtest 3: Use a stylize function that throws an exception.
    const output = util.inspect(target, {
      stylize: common.mustCall((str) => {
        throw new Error('oops');
      })
    });
    assert.strictEqual(output, '🐈');
    assert.strictEqual(typeof target.ctx, 'object');
    const objectGraph = fullObjectGraph(target);
    assert(!objectGraph.has(Object));
    assert(!objectGraph.has(Function));
  }

  function fullObjectGraph(value) {
    const graph = new Set([value]);

    for (const entry of graph) {
      if ((typeof entry !== 'object' && typeof entry !== 'function') ||
          entry === null) {
        continue;
      }

      graph.add(Object.getPrototypeOf(entry));
      const descriptors = Object.values(
        Object.getOwnPropertyDescriptors(entry));
      for (const descriptor of descriptors) {
        graph.add(descriptor.value);
        graph.add(descriptor.set);
        graph.add(descriptor.get);
      }
    }

    return graph;
  }

  // Consistency check.
  assert(fullObjectGraph(global).has(Function.prototype));
}

{
  // Confirm that own constructor value displays correctly.

  function Fhqwhgads() {}

  const sterrance = new Fhqwhgads();
  sterrance.constructor = Fhqwhgads;

  assert.strictEqual(
    util.inspect(sterrance, { showHidden: true }),
    'Fhqwhgads {\n' +
      '  constructor: <ref *1> [Function: Fhqwhgads] {\n' +
      '    [length]: 0,\n' +
      "    [name]: 'Fhqwhgads',\n" +
      '    [prototype]: { [constructor]: [Circular *1] }\n' +
      '  }\n' +
      '}'
  );
}

{
  // Confirm null prototype of generator prototype displays as expected.

  function getProtoOfProto() {
    return Object.getPrototypeOf(Object.getPrototypeOf(function* () {}));
  }

  function* generator() {}

  const generatorPrototype = Object.getPrototypeOf(generator);
  const originalProtoOfProto = Object.getPrototypeOf(generatorPrototype);
  assert.strictEqual(getProtoOfProto(), originalProtoOfProto);
  Object.setPrototypeOf(generatorPrototype, null);
  assert.notStrictEqual(getProtoOfProto, originalProtoOfProto);

  // This is the actual test. The other assertions in this block are about
  // making sure the test is set up correctly and isn't polluting other tests.
  assert.strictEqual(
    util.inspect(generator, { showHidden: true }),
    '[GeneratorFunction: generator] {\n' +
    '  [length]: 0,\n' +
    "  [name]: 'generator',\n" +
    "  [prototype]: Object [Generator] { [Symbol(Symbol.toStringTag)]: 'Generator' },\n" + // eslint-disable-line max-len
    "  [Symbol(Symbol.toStringTag)]: 'GeneratorFunction'\n" +
    '}'
  );

  // Reset so we don't pollute other tests
  Object.setPrototypeOf(generatorPrototype, originalProtoOfProto);
  assert.strictEqual(getProtoOfProto(), originalProtoOfProto);
}

{
  // Test for when breakLength results in a single column.
  const obj = Array(9).fill('fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf');
  assert.strictEqual(
    util.inspect(obj, { breakLength: 256 }),
    '[\n' +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf',\n" +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf',\n" +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf',\n" +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf',\n" +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf',\n" +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf',\n" +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf',\n" +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf',\n" +
    "  'fhqwhgadshgnsdhjsdbkhsdabkfabkveybvf'\n" +
    ']'
  );
}

{
  assert.strictEqual(
    util.inspect({ ['__proto__']: { a: 1 } }),
    "{ ['__proto__']: { a: 1 } }"
  );
}

{
  const { numericSeparator } = util.inspect.defaultOptions;
  util.inspect.defaultOptions.numericSeparator = true;

  assert.strictEqual(
    // eslint-disable-next-line no-loss-of-precision
    util.inspect(1234567891234567891234),
    '1.234567891234568e+21'
  );
  assert.strictEqual(
    util.inspect(123456789.12345678),
    '123_456_789.123_456_78'
  );

  assert.strictEqual(util.inspect(10_000_000), '10_000_000');
  assert.strictEqual(util.inspect(1_000_000), '1_000_000');
  assert.strictEqual(util.inspect(100_000), '100_000');
  assert.strictEqual(util.inspect(99_999.9), '99_999.9');
  assert.strictEqual(util.inspect(9_999), '9_999');
  assert.strictEqual(util.inspect(999), '999');
  assert.strictEqual(util.inspect(NaN), 'NaN');
  assert.strictEqual(util.inspect(Infinity), 'Infinity');
  assert.strictEqual(util.inspect(-Infinity), '-Infinity');

  assert.strictEqual(
    util.inspect(new Float64Array([100_000_000])),
    'Float64Array(1) [ 100_000_000 ]'
  );
  assert.strictEqual(
    util.inspect(new BigInt64Array([9_100_000_100n])),
    'BigInt64Array(1) [ 9_100_000_100n ]'
  );

  assert.strictEqual(
    util.inspect(123456789),
    '123_456_789'
  );
  assert.strictEqual(
    util.inspect(123456789n),
    '123_456_789n'
  );

  util.inspect.defaultOptions.numericSeparator = numericSeparator;

  assert.strictEqual(
    util.inspect(123456789.12345678, { numericSeparator: true }),
    '123_456_789.123_456_78'
  );

  assert.strictEqual(
    util.inspect(-123456789.12345678, { numericSeparator: true }),
    '-123_456_789.123_456_78'
  );
}