feat(expect): Add equality support for Array Buffers to ToStrictEqual…

… method (#11805)

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Features
 
+- `[expect]` Add equality checks for Array Buffers in `expect.ToStrictEqual()` ([#11805](https://github.com/facebook/jest/pull/11805))
+
 ### Fixes
 
 ### Chore & Maintenance

packages/expect/src/__tests__/matchers.test.js

@@ -426,6 +426,30 @@ describe('.toStrictEqual()', () => {
   it('does not pass when equally sparse arrays have different values', () => {
     expect([, 1]).not.toStrictEqual([, 2]);
   });
+
+  it('does not pass when ArrayBuffers are not equal', () => {
+    expect(Uint8Array.from([1, 2]).buffer).not.toStrictEqual(
+      Uint8Array.from([0, 0]).buffer,
+    );
+    expect(Uint8Array.from([2, 1]).buffer).not.toStrictEqual(
+      Uint8Array.from([2, 2]).buffer,
+    );
+    expect(Uint8Array.from([]).buffer).not.toStrictEqual(
+      Uint8Array.from([1]).buffer,
+    );
+  });
+
+  it('passes for matching buffers', () => {
+    expect(Uint8Array.from([1]).buffer).toStrictEqual(
+      Uint8Array.from([1]).buffer,
+    );
+    expect(Uint8Array.from([]).buffer).toStrictEqual(
+      Uint8Array.from([]).buffer,
+    );
+    expect(Uint8Array.from([9, 3]).buffer).toStrictEqual(
+      Uint8Array.from([9, 3]).buffer,
+    );
+  });
   /* eslint-enable */
 });
 

packages/expect/src/__tests__/utils.test.ts

@@ -8,6 +8,7 @@
 
 import {stringify} from 'jest-matcher-utils';
 import {
+  arrayBufferEquality,
   emptyObject,
   getObjectSubset,
   getPath,
@@ -466,3 +467,23 @@ describe('iterableEquality', () => {
     expect(iterableEquality(a, b)).toBe(true);
   });
 });
+
+describe('arrayBufferEquality', () => {
+  test('returns undefined if given a non instance of ArrayBuffer', () => {
+    expect(arrayBufferEquality(2, 's')).toBeUndefined();
+    expect(arrayBufferEquality(undefined, 2)).toBeUndefined();
+    expect(arrayBufferEquality(new Date(), new ArrayBuffer(2))).toBeUndefined();
+  });
+
+  test('returns false when given non-matching buffers', () => {
+    const a = Uint8Array.from([2, 4]).buffer;
+    const b = Uint16Array.from([1, 7]).buffer;
+    expect(arrayBufferEquality(a, b)).not.toBeTruthy();
+  });
+
+  test('returns true when given matching buffers', () => {
+    const a = Uint8Array.from([1, 2]).buffer;
+    const b = Uint8Array.from([1, 2]).buffer;
+    expect(arrayBufferEquality(a, b)).toBeTruthy();
+  });
+});

packages/expect/src/matchers.ts

@@ -40,6 +40,7 @@ import {
 } from './print';
 import type {MatcherState, MatchersObject} from './types';
 import {
+  arrayBufferEquality,
   getObjectSubset,
   getPath,
   iterableEquality,
@@ -61,6 +62,7 @@ const toStrictEqualTesters = [
   iterableEquality,
   typeEquality,
   sparseArrayEquality,
+  arrayBufferEquality,
 ];
 
 type ContainIterable =

packages/expect/src/utils.ts

@@ -319,6 +319,32 @@ export const typeEquality = (a: any, b: any): boolean | undefined => {
   return false;
 };
 
+export const arrayBufferEquality = (
+  a: unknown,
+  b: unknown,
+): boolean | undefined => {
+  if (!(a instanceof ArrayBuffer) || !(b instanceof ArrayBuffer)) {
+    return undefined;
+  }
+
+  const dataViewA = new DataView(a);
+  const dataViewB = new DataView(b);
+
+  // Buffers are not equal when they do not have the same byte length
+  if (dataViewA.byteLength !== dataViewB.byteLength) {
+    return false;
+  }
+
+  // Check if every byte value is equal to each other
+  for (let i = 0; i < dataViewA.byteLength; i++) {
+    if (dataViewA.getUint8(i) !== dataViewB.getUint8(i)) {
+      return false;
+    }
+  }
+
+  return true;
+};
+
 export const sparseArrayEquality = (
   a: unknown,
   b: unknown,