Add option testSequencer allow user use custom sequencer. (#8223)

Author: WeiAnAn

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ### Features
 
+- `[@jest/core, @jest/test-sequencer]` Move `testSequencer` to individual package `@jest/test-sequencer` ([#8223](https://github.com/facebook/jest/pull/8223))
+- `[@jest/core, jest-cli, jest-config]` Add option `testSequencer` allow user use custom sequencer. ([#8223](https://github.com/facebook/jest/pull/8223))
+
 ### Fixes
 
 ### Chore & Maintenance

docs/CLI.md

@@ -297,6 +297,10 @@ An array of regexp pattern strings that is tested against all tests paths before
 
 Lets you specify a custom test runner.
 
+### `--testSequencer=<path>`
+
+Lets you specify a custom test sequencer. Please refer to the documentation of the corresponding configuration property for details.
+
 ### `--updateSnapshot`
 
 Alias: `-u`. Use this flag to re-record every snapshot that fails during this test run. Can be used together with a test suite pattern or with `--testNamePattern` to re-record snapshots.

docs/Configuration.md

@@ -1018,6 +1018,31 @@ function testRunner(
 
 An example of such function can be found in our default [jasmine2 test runner package](https://github.com/facebook/jest/blob/master/packages/jest-jasmine2/src/index.js).
 
+### `testSequencer` [string]
+
+Default: `@jest/test-sequencer`
+
+This option allows you to use a custom sequencer instead of Jest's default.
+
+Example:
+
+Sort test path alphabetically
+
+```js
+const Sequencer = require('@jest/test-sequencer').default;
+
+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;
+```
+
 ### `testURL` [string]
 
 Default: `http://localhost`

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

@@ -117,6 +117,7 @@ exports[`--showConfig outputs config info and exits 1`] = `
     "testFailureExitCode": 1,
     "testPathPattern": "",
     "testResultsProcessor": null,
+    "testSequencer": "@jest/test-sequencer",
     "updateSnapshot": "all",
     "useStderr": false,
     "verbose": null,

e2e/__tests__/customTestSequencers.test.ts

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import path from 'path';
+import runJest from '../runJest';
+import {extractSummary} from '../Utils';
+const dir = path.resolve(__dirname, '../custom-test-sequencer');
+
+test('run prioritySequence first', () => {
+  const result = runJest(dir, ['-i']);
+  expect(result.status).toBe(0);
+  const sequence = extractSummary(result.stderr)
+    .rest.replace(/PASS /g, '')
+    .split('\n');
+  expect(sequence).toEqual([
+    './a.test.js',
+    './b.test.js',
+    './c.test.js',
+    './d.test.js',
+    './e.test.js',
+  ]);
+});

e2e/custom-test-sequencer/a.test.js

@@ -0,0 +1,7 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+test('a', () => {});

e2e/custom-test-sequencer/b.test.js

@@ -0,0 +1,7 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+test('b', () => {});

e2e/custom-test-sequencer/c.test.js

@@ -0,0 +1,7 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+test('c', () => {});

e2e/custom-test-sequencer/d.test.js

@@ -0,0 +1,7 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+test('d', () => {});

e2e/custom-test-sequencer/e.test.js

@@ -0,0 +1,7 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+test('e', () => {});