Revert jestjs#7089 and add tests to catch the regression in the future.

e2e/__tests__/__snapshots__/snapshotSerializers.test.ts.snap

@@ -2,10 +2,24 @@
 
 exports[`Snapshot serializers renders snapshot 1`] = `
 Object {
+  "snapshot serializers works with array of strings in property matcher 1": "
+Object {
+  \\"arrayOfStrings\\": Array [
+    \\"stream\\",
+  ],
+}
+",
   "snapshot serializers works with default serializers 1": "
 <div
   id=\\"foo\\"
 />
+",
+  "snapshot serializers works with expect.XXX within array in property matcher 1": "
+Object {
+  \\"arrayOfStrings\\": Array [
+    Any<String>,
+  ],
+}
 ",
   "snapshot serializers works with first plugin 1": "foo - 1",
   "snapshot serializers works with nested serializable objects 1": "foo - bar - 2",

e2e/__tests__/snapshotSerializers.test.ts

@@ -20,8 +20,8 @@ const runAndAssert = () => {
     '--no-cache',
   ]);
   const json = result.json;
-  expect(json.numTotalTests).toBe(7);
-  expect(json.numPassedTests).toBe(7);
+  expect(json.numTotalTests).toBe(9);
+  expect(json.numPassedTests).toBe(9);
   expect(json.numFailedTests).toBe(0);
   expect(json.numPendingTests).toBe(0);
   expect(result.status).toBe(0);

e2e/snapshot-serializers/__tests__/snapshot.test.js

@@ -91,4 +91,20 @@ describe('snapshot serializers', () => {
     });
     expect(test).toMatchSnapshot();
   });
+
+  it('works with array of strings in property matcher', () => {
+    expect({
+      arrayOfStrings: ['stream'],
+    }).toMatchSnapshot({
+      arrayOfStrings: ['stream'],
+    });
+  });
+
+  it('works with expect.XXX within array in property matcher', () => {
+    expect({
+      arrayOfStrings: ['stream'],
+    }).toMatchSnapshot({
+      arrayOfStrings: [expect.any(String)],
+    });
+  });
 });

packages/jest-snapshot/src/__tests__/utils.test.ts

@@ -9,7 +9,6 @@ jest.mock('fs');
 
 import fs from 'fs';
 import path from 'path';
-import assert from 'assert';
 import chalk from 'chalk';
 
 import {
@@ -202,85 +201,14 @@ test('serialize handles \\r\\n', () => {
 
 describe('DeepMerge', () => {
   it('Correctly merges objects with property matchers', () => {
-    /* eslint-disable sort-keys */
-    // to keep keys in numerical order rather than alphabetical
-    const target = {
-      data: {
-        one: 'one',
-        two: 'two',
-        three: [
-          {
-            four: 'four',
-            five: 'five',
-          },
-          // Include an array element not present in the propertyMatchers
-          {
-            six: 'six',
-            seven: 'seven',
-          },
-        ],
-        eight: [{nine: 'nine'}],
-      },
-    };
+    const target = {data: {bar: 'bar', foo: 'foo'}};
 
     const matcher = expect.any(String);
-    const propertyMatchers = {
-      data: {
-        two: matcher,
-        three: [
-          {
-            four: matcher,
-          },
-        ],
-        eight: [
-          {nine: matcher},
-          // Include an array element not present in the target
-          {ten: matcher},
-        ],
-      },
-    };
+    const propertyMatchers = {data: {foo: matcher}};
 
     const mergedOutput = deepMerge(target, propertyMatchers);
 
-    // Use assert.deepStrictEqual() instead of expect().toStrictEqual()
-    // since we want to actually validate that we got the matcher
-    // rather than treat it specially the way that expect() does
-    assert.deepStrictEqual(mergedOutput, {
-      data: {
-        one: 'one',
-        two: matcher,
-        three: [
-          {
-            four: matcher,
-            five: 'five',
-          },
-          {
-            six: 'six',
-            seven: 'seven',
-          },
-        ],
-        eight: [{nine: matcher}, {ten: matcher}],
-      },
-    });
-
-    // Ensure original target is not modified
-    expect(target).toStrictEqual({
-      data: {
-        one: 'one',
-        two: 'two',
-        three: [
-          {
-            four: 'four',
-            five: 'five',
-          },
-          {
-            six: 'six',
-            seven: 'seven',
-          },
-        ],
-        eight: [{nine: 'nine'}],
-      },
-    });
-    /* eslint-enable sort-keys */
+    expect(mergedOutput).toStrictEqual({data: {bar: 'bar', foo: matcher}});
+    expect(target).toStrictEqual({data: {bar: 'bar', foo: 'foo'}});
   });
 });

packages/jest-snapshot/src/utils.ts

@@ -178,30 +178,13 @@ export const saveSnapshotFile = (
   );
 };
 
-const deepMergeArray = (target: Array<any>, source: Array<any>) => {
-  // Clone target
-  const mergedOutput = target.slice();
-
-  source.forEach((element, index) => {
-    if (typeof mergedOutput[index] === 'undefined') {
-      mergedOutput[index] = element;
-    } else {
-      mergedOutput[index] = deepMerge(target[index], element);
-    }
-  });
-
-  return mergedOutput;
-};
-
 export const deepMerge = (target: any, source: any) => {
   const mergedOutput = {...target};
   if (isObject(target) && isObject(source)) {
     Object.keys(source).forEach(key => {
       if (isObject(source[key]) && !source[key].$$typeof) {
         if (!(key in target)) Object.assign(mergedOutput, {[key]: source[key]});
         else mergedOutput[key] = deepMerge(target[key], source[key]);
-      } else if (Array.isArray(source[key])) {
-        mergedOutput[key] = deepMergeArray(target[key], source[key]);
       } else {
         Object.assign(mergedOutput, {[key]: source[key]});
       }