Revert "fix: don't mutate the sample in expect.objectContaining() (je…

…stjs#10711)" This reverts commit f84a807.
SimenB · Nov 2, 2020 · 46b0838 · 46b0838
1 parent 038d8be
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Showing 3 changed files with 7 additions and 13 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -9,7 +9,6 @@
 - `[babel-plugin-jest-hoist]` Preserve order of hoisted mock nodes within containing block ([#10536](https://github.com/facebook/jest/pull/10536))
 - `[babel-plugin-jest-hoist]` Hoist pure constants to support experimental JSX transform in hoisted mocks ([#10723](https://github.com/facebook/jest/pull/10723))
 - `[babel-preset-jest]` Update `babel-preset-current-node-syntax` to support top level await ([#10747](https://github.com/facebook/jest/pull/10747))
-- `[expect]` Stop modifying the sample in `expect.objectContaining()` ([#10711](https://github.com/facebook/jest/pull/10711))
 - `[jest-circus, jest-jasmine2]` fix: don't assume `stack` is always a string ([#10697](https://github.com/facebook/jest/pull/10697))
 - `[jest-config]` Fix bug introduced in watch mode by PR [#10678](https://github.com/facebook/jest/pull/10678/files#r511037803) ([#10692](https://github.com/facebook/jest/pull/10692))
 - `[jest-config]` Throw correct error for missing preset modules ([#10737](https://github.com/facebook/jest/pull/10737))

diff --git a/packages/expect/src/__tests__/asymmetricMatchers.test.ts b/packages/expect/src/__tests__/asymmetricMatchers.test.ts
@@ -210,14 +210,6 @@ test('ObjectContaining throws for non-objects', () => {
   jestExpect(() => objectContaining(1337).asymmetricMatch()).toThrow();
 });
 
-test('ObjectContaining does not mutate the sample', () => {
-  const sample = {foo: {bar: {}}};
-  const sample_json = JSON.stringify(sample);
-  expect({foo: {bar: {}}}).toEqual(expect.objectContaining(sample));
-
-  expect(JSON.stringify(sample)).toEqual(sample_json);
-});
-
 test('ObjectNotContaining matches', () => {
   [
     objectNotContaining({}).asymmetricMatch('jest'),

diff --git a/packages/expect/src/asymmetricMatchers.ts b/packages/expect/src/asymmetricMatchers.ts
@@ -177,15 +177,18 @@ class ObjectContaining extends AsymmetricMatcher<Record<string, unknown>> {
       return true;
     } else {
       for (const property in this.sample) {
-        const expected =
+        if (
           typeof this.sample[property] === 'object' &&
           !(this.sample[property] instanceof AsymmetricMatcher)
-            ? objectContaining(this.sample[property] as Record<string, unknown>)
-            : this.sample[property];
+        ) {
+          this.sample[property] = objectContaining(
+            this.sample[property] as Record<string, unknown>,
+          );
+        }
 
         if (
           !hasProperty(other, property) ||
-          !equals(expected, other[property])
+          !equals(this.sample[property], other[property])
         ) {
           return false;
         }