fix: Restart a shut down worker before sending it a task.

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

@@ -0,0 +1,9 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`all 3 test files should complete 1`] = `
+"Test Suites: 1 failed, 2 passed, 3 total
+Tests:       2 passed, 2 total
+Snapshots:   0 total
+Time:        <<REPLACED>>
+Ran all test suites."
+`;

e2e/__tests__/workerRestartBeforeSend.test.ts

@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {extractSummary} from '../Utils';
+import runJest from '../runJest';
+
+it('all 3 test files should complete', () => {
+  const result = runJest('worker-restart-before-send');
+  const {summary} = extractSummary(result.stderr);
+  expect(summary).toMatchSnapshot();
+});

e2e/snapshot/__tests__/__snapshots__/snapshot.test.js.snap

@@ -0,0 +1,31 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`snapshot is not influenced by previous counter 1`] = `
+{
+  "a": 43,
+  "b": "43",
+  "c": "fortythree",
+}
+`;
+
+exports[`snapshot works with \\r\\n 1`] = `
+"<div>
+</div>"
+`;
+
+exports[`snapshot works with plain objects and the title has \`escape\` characters 1`] = `
+{
+  "a": 1,
+  "b": "2",
+  "c": "three\`",
+}
+`;
+
+exports[`snapshot works with plain objects and the title has \`escape\` characters 2`] = `
+{
+  "a": 1,
+  "b": "2",
+  "c": "three\`",
+  "d": "4",
+}
+`;

e2e/snapshot/__tests__/__snapshots__/snapshot.test_copy.js.snap

@@ -0,0 +1,31 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`snapshot is not influenced by previous counter 1`] = `
+{
+  "a": 43,
+  "b": "43",
+  "c": "fortythree",
+}
+`;
+
+exports[`snapshot works with \\r\\n 1`] = `
+"<div>
+</div>"
+`;
+
+exports[`snapshot works with plain objects and the title has \`escape\` characters 1`] = `
+{
+  "a": 1,
+  "b": "2",
+  "c": "three\`",
+}
+`;
+
+exports[`snapshot works with plain objects and the title has \`escape\` characters 2`] = `
+{
+  "a": 1,
+  "b": "2",
+  "c": "three\`",
+  "d": "4",
+}
+`;

e2e/snapshot/__tests__/snapshot.test_copy.js

@@ -0,0 +1,41 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
+
+describe('snapshot', () => {
+  it('works with plain objects and the title has `escape` characters', () => {
+    const test = {
+      a: 1,
+      b: '2',
+      c: 'three`',
+    };
+    expect(test).toMatchSnapshot();
+    test.d = '4';
+    expect(test).toMatchSnapshot();
+  });
+
+  it('is not influenced by previous counter', () => {
+    const test = {
+      a: 43,
+      b: '43',
+      c: 'fortythree',
+    };
+    expect(test).toMatchSnapshot();
+  });
+
+  it('cannot be used with .not', () => {
+    expect(() => expect('').not.toMatchSnapshot()).toThrow(
+      'Snapshot matchers cannot be used with not',
+    );
+  });
+
+  // Issue reported here: https://github.com/facebook/jest/issues/2969
+  it('works with \\r\\n', () => {
+    expect('<div>\r\n</div>').toMatchSnapshot();
+  });
+});

e2e/to-match-inline-snapshot/__tests__/custom-matchers.test.js

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+const {toMatchInlineSnapshot} = require('jest-snapshot');
+expect.extend({
+  toMatchCustomInlineSnapshot(received, ...args) {
+    return toMatchInlineSnapshot.call(this, received, ...args);
+  },
+});
+test('inline snapshots', () => {
+  expect({apple: 'original value'}).toMatchCustomInlineSnapshot();
+});

e2e/to-match-snapshot/__tests__/accept-custom-snapshot-name.test.js

@@ -0,0 +1,12 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+test('accepts custom snapshot name', () => {
+  expect(true).toMatchSnapshot('custom-name');
+});

e2e/worker-restart-before-send/__tests__/test1.js

@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+test('jest-worker killed', async () => {
+  await new Promise(resolve => setTimeout(resolve, 100));
+});
+
+setTimeout(() => {
+  // Self-kill process.
+  process.kill(process.pid);
+}, 50);

e2e/worker-restart-before-send/__tests__/test2.js

@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+test('basic test', async () => {
+  await new Promise(resolve => setTimeout(resolve, 100));
+});

e2e/worker-restart-before-send/__tests__/test3.js

@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+test('basic test', async () => {
+  await new Promise(resolve => setTimeout(resolve, 100));
+});

e2e/worker-restart-before-send/package.json

@@ -0,0 +1,6 @@
+{
+  "jest": {
+    "maxWorkers": 2,
+    "testSequencer": "./testSequencer.js"
+  }
+}

e2e/worker-restart-before-send/testSequencer.js

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+const Sequencer = require('@jest/test-sequencer').default;
+
+// Ensure that test1.js runs first.
+class CustomSequencer extends Sequencer {
+  sort(tests) {
+    // Test structure information
+    // https://github.com/facebook/jest/blob/6b8b1404a1d9254e7d5d90a8934087a9c9899dab/packages/jest-runner/src/types.ts#L17-L21
+    const copyTests = Array.from(tests);
+    return copyTests.sort((testA, testB) => (testA.path > testB.path ? 1 : -1));
+  }
+}
+
+module.exports = CustomSequencer;

packages/jest-worker/src/WorkerPool.ts

@@ -24,6 +24,7 @@ class WorkerPool extends BaseWorkerPool implements WorkerPoolInterface {
     onEnd: OnEnd,
     onCustomMessage: OnCustomMessage,
   ): void {
+    this.restartWorkerIfShutDown(workerId);
     this.getWorkerById(workerId).send(request, onStart, onEnd, onCustomMessage);
   }
 

packages/jest-worker/src/base/BaseWorkerPool.ts

@@ -13,6 +13,7 @@ import {
   WorkerInterface,
   WorkerOptions,
   WorkerPoolOptions,
+  WorkerStates,
 } from '../types';
 
 // How long to wait for the child process to terminate
@@ -28,9 +29,11 @@ export default class BaseWorkerPool {
   private readonly _stdout: NodeJS.ReadableStream;
   protected readonly _options: WorkerPoolOptions;
   private readonly _workers: Array<WorkerInterface>;
+  private readonly _workerPath: string;
 
   constructor(workerPath: string, options: WorkerPoolOptions) {
     this._options = options;
+    this._workerPath = workerPath;
     this._workers = new Array(options.numWorkers);
 
     const stdout = mergeStream();
@@ -84,6 +87,24 @@ export default class BaseWorkerPool {
     return this._workers[workerId];
   }
 
+  restartWorkerIfShutDown(workerId: number): void {
+    if (this._workers[workerId].state === WorkerStates.SHUT_DOWN) {
+      const {forkOptions, maxRetries, resourceLimits, setupArgs} =
+        this._options;
+      const workerOptions: WorkerOptions = {
+        forkOptions,
+        idleMemoryLimit: this._options.idleMemoryLimit,
+        maxRetries,
+        resourceLimits,
+        setupArgs,
+        workerId,
+        workerPath: this._workerPath,
+      };
+      const worker = this.createWorker(workerOptions);
+      this._workers[workerId] = worker;
+    }
+  }
+
   createWorker(_workerOptions: WorkerOptions): WorkerInterface {
     throw Error('Missing method createWorker in WorkerPool');
   }