update docs and tests

Author: SRHerzog

doc/api/fs.md

@@ -760,7 +760,8 @@ changes:
                  strings anymore.
 -->
 
-* `data` {string|Buffer|TypedArray|DataView|ArrayBuffer|AsyncIterable|Iterable|Stream}
+* `data` {string|Buffer|TypedArray|DataView|ArrayBuffer|AsyncIterable|
+  Iterable|Stream}
 * `options` {Object|string}
   * `encoding` {string|null} The expected character encoding when `data` is a
     string. **Default:** `'utf8'`
@@ -799,8 +800,8 @@ Write an array of {ArrayBufferView}s or {ArrayBuffer}s to the file.
 The promise is resolved with an object containing a two properties:
 
 * `bytesWritten` {integer} the number of bytes written
-* `buffers` {Buffer\[]|TypedArray\[]|DataView\[]|ArrayBuffer\[]} a reference to the `buffers`
-  input.
+* `buffers` {Buffer\[]|TypedArray\[]|DataView\[]|ArrayBuffer\[]} a reference
+  to the `buffers` input.
 
 It is unsafe to call `writev()` multiple times on the same file without waiting
 for the promise to be resolved (or rejected).
@@ -1693,7 +1694,8 @@ changes:
 -->
 
 * `file` {string|Buffer|URL|FileHandle} filename or `FileHandle`
-* `data` {string|Buffer|TypedArray|DataView|ArrayBuffer|AsyncIterable|Iterable|Stream}
+* `data` {string|Buffer|TypedArray|DataView|ArrayBuffer|AsyncIterable
+  |Iterable|Stream}
 * `options` {Object|string}
   * `encoding` {string|null} **Default:** `'utf8'`
   * `mode` {integer} **Default:** `0o666`
@@ -4898,8 +4900,8 @@ changes:
   * `bytesWritten` {integer}
   * `buffers` {ArrayBufferView\[]}
 
-Write an array of `ArrayBufferView`s or `ArrayBuffer`s to the file specified by `fd` using
-`writev()`.
+Write an array of `ArrayBufferView`s or `ArrayBuffer`s to the file specified
+by `fd` using `writev()`.
 
 `position` is the offset from the beginning of the file where this data
 should be written. If `typeof position !== 'number'`, the data will be written

lib/internal/fs/utils.js

@@ -21,6 +21,7 @@ const {
   StringPrototypeIncludes,
   Symbol,
   TypedArrayPrototypeIncludes,
+  Uint8Array,
 } = primordials;
 
 const { Buffer } = require('buffer');

test/parallel/test-fs-writev-sync.js

@@ -56,6 +56,27 @@ const getFileName = (i) => path.join(tmpdir.path, `writev_sync_${i}.txt`);
   assert(Buffer.concat(bufferArr).equals(fs.readFileSync(filename)));
 }
 
+// fs.writevSync with array of ArrayBuffers without position
+{
+  const filename = getFileName(2);
+  const fd = fs.openSync(filename, 'w');
+
+  const buffer = Buffer.from(expected);
+  const arrayBuffer = buffer.buffer.slice(buffer.byteOffset, buffer.byteOffset + buffer.byteLength);
+  const arrayBufferArr = [arrayBuffer, arrayBuffer, arrayBuffer];
+  const expectedLength = arrayBufferArr.length * arrayBuffer.byteLength;
+
+  let written = fs.writevSync(fd, [Buffer.from('')]);
+  assert.strictEqual(written, 0);
+
+  written = fs.writevSync(fd, arrayBufferArr);
+  assert.strictEqual(written, expectedLength);
+
+  fs.closeSync(fd);
+  const expectedResult = Buffer.concat(arrayBufferArr.map((buf) => new Uint8Array(buf)));
+  assert(expectedResult.equals(fs.readFileSync(filename)));
+}
+
 // fs.writevSync with empty array of buffers
 {
   const filename = getFileName(3);

test/parallel/test-fs-writev.js

@@ -88,19 +88,10 @@ const getFileName = (i) => path.join(tmpdir.path, `writev_${i}.txt`);
     assert.deepStrictEqual(arrayBufferArr, buffers);
 
     const expectedLength = arrayBufferArr.length * arrayBuffer.byteLength;
-    console.log({ arrLength: arrayBufferArr.length, byteLength: arrayBuffer.byteLength })
     assert.deepStrictEqual(written, expectedLength);
     fs.closeSync(fd);
     const expectedResult = Buffer.concat(arrayBufferArr.map((buf) => new Uint8Array(buf)));
-    const gotResult = fs.readFileSync(filename);
-    for (let i = 0; i < expectedResult.byteLength; i++) {
-      if (expectedResult[i] !== gotResult[i]) {
-        console.log({ i, expected: expectedResult[i], got: gotResult[i], expectedLength })
-        break;
-      }
-    }
-    // console.log({ expectedResult, _____gotResult, equal: expectedResult.compare(gotResult) });
-    assert(expectedResult.equals(gotResult));
+    assert(expectedResult.equals(fs.readFileSync(filename)));
   });
 
   fs.writev(fd, arrayBufferArr, done);