Add custom equality matcher to support ES 2015 iterables

packages/jest-jasmine2/src/__tests__/iterators-test.js

@@ -0,0 +1,75 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @emails oncall+jsinfra
+ */
+'use strict';
+
+describe('iterators', () => {
+
+  it('works for arrays', () => {
+    const mixedArray = [1, {}, []];
+
+    expect(mixedArray).toEqual(mixedArray);
+    expect([1, 2, 3]).toEqual([1, 2, 3]);
+    expect([1]).not.toEqual([2]);
+    expect([1, 2, 3]).not.toEqual([1, 2]);
+    expect([1, 2, 3]).not.toEqual([1, 2, 3, 4]);
+  });
+
+  it('works for custom iterables', () => {
+    const iterable = {
+      0: 'a',
+      1: 'b',
+      2: 'c',
+      length: 3,
+      [Symbol.iterator]: Array.prototype[Symbol.iterator],
+    };
+    const expectedIterable = {
+      0: 'a',
+      1: 'b',
+      2: 'c',
+      length: 3,
+      [Symbol.iterator]: Array.prototype[Symbol.iterator],
+    };
+    expect(iterable).toEqual(expectedIterable);
+    expect(iterable).not.toEqual(['a', 'b']);
+    expect(iterable).not.toEqual(['a', 'b', 'c']);
+    expect(iterable).not.toEqual(['a', 'b', 'c', 'd']);
+  });
+
+  it('works for Sets', () => {
+    const numbers = [1, 2, 3, 4];
+    const setOfNumbers = new Set(numbers);
+    expect(setOfNumbers).not.toEqual(new Set());
+    expect(setOfNumbers).not.toBe(numbers);
+    expect(setOfNumbers).not.toEqual([1, 2]);
+    expect(setOfNumbers).not.toEqual([1, 2, 3]);
+    expect(setOfNumbers).toEqual(new Set(numbers));
+
+    const nestedSets = new Set([new Set([1, 2])]);
+    expect(nestedSets).not.toEqual(new Set([new Set([1, 4])]));
+    expect(nestedSets).toEqual(new Set([new Set([1, 2])]));
+  });
+
+  it('works for Maps', () => {
+    const keyValuePairs = [['key1', 'value1'], ['key2', 'value2']];
+    const smallerKeyValuePairs = [['key1', 'value1']];
+    const biggerKeyValuePairs = [
+      ['key1', 'value1'], ['key2', 'value2'], ['key3', 'value3'],
+    ];
+    const map = new Map(keyValuePairs);
+    expect(map).not.toEqual(smallerKeyValuePairs);
+    expect(map).not.toEqual(new Map(smallerKeyValuePairs));
+    expect(map).not.toEqual(biggerKeyValuePairs);
+    expect(map).not.toEqual(new Map(biggerKeyValuePairs));
+    expect(map).not.toEqual(keyValuePairs);
+    expect(map).not.toBe(keyValuePairs);
+    expect(map).toEqual(new Map(keyValuePairs));
+  });
+
+});

packages/jest-jasmine2/src/index.js

@@ -69,7 +69,46 @@ function jasmine2(config, environment, moduleLoader, testPath) {
       moduleLoader.requireModule(null, config.setupTestFrameworkScriptFile);
     }
   });
+
+  const hasIterator = object => !!(object != null && object[Symbol.iterator]);
+  const iterableEquality = (a, b) => {
+    if (
+      typeof a !== 'object' ||
+      typeof b !== 'object' ||
+      Array.isArray(a) ||
+      Array.isArray(b) ||
+      !hasIterator(a) ||
+      !hasIterator(b)
+    ) {
+      return undefined;
+    }
+    if (a.constructor !== b.constructor) {
+      return false;
+    }
+    const bIterator = b[Symbol.iterator]();
+
+    for (const aValue of a) {
+      const nextB = bIterator.next();
+      if (
+        nextB.done ||
+        !jasmine.matchersUtil.equals(
+          aValue,
+          nextB.value,
+          [iterableEquality]
+        )
+      ) {
+        return false;
+      }
+    }
+    if (!bIterator.next().done) {
+      return false;
+    }
+    return true;
+  };
+
   env.beforeEach(() => {
+    jasmine.addCustomEqualityTester(iterableEquality);
+
     jasmine.addMatchers({
       toBeCalled: () => ({
         compare: (actual, expected) => {