[jest-get-type] Simplify checking for primitive (#8416)

* [jest-get-type] Simplify checking for primitive

* Update changelog

Author: Connormiha

CHANGELOG.md

@@ -41,6 +41,7 @@
 - `[jest-runtime]` Fix module registry memory leak ([#8282](https://github.com/facebook/jest/pull/8282))
 - `[jest-resolve]` optimize resolve module path ([#8388](https://github.com/facebook/jest/pull/8388))
 - `[jest-resolve]` cache current directory ([#8412](https://github.com/facebook/jest/pull/8412))
+- `[jest-get-type]` Simplify checking for primitive ([#8416](https://github.com/facebook/jest/pull/8416))
 
 ## 24.7.1
 

packages/jest-get-type/src/__tests__/isPrimitive.test.ts

@@ -9,17 +9,30 @@
 import {isPrimitive} from '..';
 
 describe('.isPrimitive()', () => {
-  test.each([null, undefined, 100, 'hello world', true, Symbol.for('a')])(
-    'returns true when given primitive value of: %s',
-    primitive => {
-      expect(isPrimitive(primitive)).toBe(true);
-    },
-  );
+  test.each([
+    null,
+    undefined,
+    100,
+    'hello world',
+    true,
+    Symbol.for('a'),
+    0,
+    NaN,
+    Infinity,
+  ])('returns true when given primitive value of: %s', primitive => {
+    expect(isPrimitive(primitive)).toBe(true);
+  });
 
-  test.each([{}, [], () => {}, /abc/, new Map(), new Set(), new Date()])(
-    'returns false when given non primitive value of: %s',
-    value => {
-      expect(isPrimitive(value)).toBe(false);
-    },
-  );
+  test.each([
+    {},
+    [],
+    () => {},
+    /abc/,
+    new Map(),
+    new Set(),
+    new Date(),
+    Object.create(null),
+  ])('returns false when given non primitive value of: %j', value => {
+    expect(isPrimitive(value)).toBe(false);
+  });
 });

packages/jest-get-type/src/index.ts

@@ -20,15 +20,6 @@ type ValueType =
   | 'symbol'
   | 'undefined';
 
-const PRIMITIVES = new Set<ValueType>([
-  'string',
-  'number',
-  'boolean',
-  'null',
-  'undefined',
-  'symbol',
-]);
-
 // get the type of a value with handling the edge cases like `typeof []`
 // and `typeof null`
 function getType(value: unknown): ValueType {
@@ -66,6 +57,6 @@ function getType(value: unknown): ValueType {
   throw new Error(`value of unknown type: ${value}`);
 }
 
-getType.isPrimitive = (value: unknown) => PRIMITIVES.has(getType(value));
+getType.isPrimitive = (value: unknown) => Object(value) !== value;
 
 export = getType;