tests: start replacing jest with mocha, starting with unit-cli

.github/workflows/devtools.yml

@@ -65,6 +65,8 @@ jobs:
     - name: Download DevTools Frontend
       run: bash $GITHUB_WORKSPACE/lighthouse/lighthouse-core/test/chromium-web-tests/download-devtools.sh
 
+    - run: npx patch-package # TODO: remove when mocha replaces jest
+      working-directory: ${{ github.workspace }}/lighthouse
     - name: Roll Lighthouse + build DevTools
       run: bash $GITHUB_WORKSPACE/lighthouse/lighthouse-core/test/chromium-web-tests/roll-devtools.sh
 

.github/workflows/unit.yml

@@ -91,8 +91,7 @@ jobs:
     - run: yarn install --frozen-lockfile --network-timeout 1000000
     - run: yarn build-report
 
-    - name: yarn unit-cli
-      run: yarn unit-cli
+    - run: yarn unit-cli
     - run: yarn diff:sample-json
 
     # Fail if any changes were written to any source files or generated untracked files (ex, from -GA).

.gitignore

@@ -16,6 +16,7 @@ lcov.info
 lighthouse-cli/results
 results.html
 last-run-results.html
+/lighthouse-plugin-simple
 
 *.trace.json
 *.devtoolslog.json

jest.config.js

@@ -10,7 +10,6 @@ module.exports = {
   testEnvironment: 'node',
   testMatch: [
     '**/lighthouse-core/**/*-test.js',
-    '**/lighthouse-cli/**/*-test.js',
     '**/report/**/*-test.js',
     '**/lighthouse-core/test/fraggle-rock/**/*-test-pptr.js',
     '**/treemap/**/*-test.js',

lighthouse-cli/test/cli/bin-test.js

@@ -6,42 +6,40 @@
 
 import fs from 'fs';
 
-import {jest} from '@jest/globals';
+import * as td from 'testdouble';
+import jestMock from 'jest-mock';
 
-import {LH_ROOT} from '../../../root.js';
+import {LH_ROOT, readJson} from '../../../root.js';
 
-const mockRunLighthouse = jest.fn();
-
-jest.unstable_mockModule('../../run.js', () => {
-  return {runLighthouse: mockRunLighthouse};
-});
-
-const mockGetFlags = jest.fn();
-jest.unstable_mockModule('../../cli-flags.js', () => {
-  return {getFlags: mockGetFlags};
-});
-
-const mockAskPermission = jest.fn();
-jest.unstable_mockModule('../../sentry-prompt.js', () => {
-  return {askPermission: mockAskPermission};
-});
-
-const mockSentryInit = jest.fn();
-jest.mock('../../../lighthouse-core/lib/sentry.js', () => {
-  return {init: mockSentryInit};
-});
-
-const mockLoggerSetLevel = jest.fn();
-jest.unstable_mockModule('lighthouse-logger', () => {
-  return {default: {setLevel: mockLoggerSetLevel}};
-});
+const mockRunLighthouse = jestMock.fn();
+const mockGetFlags = jestMock.fn();
+const mockAskPermission = jestMock.fn();
+const mockSentryInit = jestMock.fn();
+const mockLoggerSetLevel = jestMock.fn();
 
 /** @type {import('../../bin.js')} */
 let bin;
 beforeAll(async () => {
+  await td.replaceEsm('../../run.js', {
+    runLighthouse: mockRunLighthouse,
+  });
+  await td.replaceEsm('../../cli-flags.js', {
+    getFlags: mockGetFlags,
+  });
+  await td.replaceEsm('../../sentry-prompt.js', {
+    askPermission: mockAskPermission,
+  });
+  await td.replace('../../../lighthouse-core/lib/sentry.js', {
+    init: mockSentryInit,
+  });
+  await td.replaceEsm('lighthouse-logger', undefined, {setLevel: mockLoggerSetLevel});
   bin = await import('../../bin.js');
 });
 
+afterAll(async () => {
+  await td.reset();
+});
+
 /** @type {LH.CliFlags} */
 let cliFlags;
 
@@ -177,7 +175,7 @@ describe('CLI bin', function() {
       await bin.begin();
 
       expect(getRunLighthouseArgs()[1]).toMatchObject({
-        precomputedLanternData: (await import(lanternDataFile)).default,
+        precomputedLanternData: readJson(lanternDataFile),
         precomputedLanternDataPath: lanternDataFile,
       });
     });

lighthouse-cli/test/cli/cli-flags-test.js

@@ -7,9 +7,7 @@
 import {strict as assert} from 'assert';
 import fs from 'fs';
 
-import yargs from 'yargs';
-
-import {getFlags} from '../../cli-flags.js';
+import {getFlags, getYargsParser} from '../../cli-flags.js';
 import {LH_ROOT} from '../../../root.js';
 
 /**
@@ -37,18 +35,17 @@ function snapshot(flags) {
 
 describe('CLI flags', function() {
   it('all options should have descriptions', () => {
-    getFlags('chrome://version');
-
+    const parser = getYargsParser();
     // @ts-expect-error - getGroups is private
-    const optionGroups = yargs.getGroups();
+    const optionGroups = parser.getGroups();
     /** @type {string[]} */
     const allOptions = [];
     Object.keys(optionGroups).forEach(key => {
       allOptions.push(...optionGroups[key]);
     });
     const optionsWithDescriptions =
       // @ts-expect-error - getUsageInstance is private
-      Object.keys(yargs.getInternalMethods().getUsageInstance().getDescriptions());
+      Object.keys(parser.getInternalMethods().getUsageInstance().getDescriptions());
 
     allOptions.forEach(opt => {
       assert.ok(optionsWithDescriptions.includes(opt), `cli option '${opt}' has no description`);

lighthouse-cli/test/cli/printer-test.js

@@ -8,7 +8,9 @@ import {strict as assert} from 'assert';
 import fs from 'fs';
 
 import * as Printer from '../../printer.js';
-import sampleResults from '../../../lighthouse-core/test/results/sample_v2.json';
+import {readJson} from '../../../root.js';
+
+const sampleResults = readJson('lighthouse-core/test/results/sample_v2.json');
 
 describe('Printer', () => {
   it('accepts valid output paths', () => {

lighthouse-cli/test/cli/run-test.js

@@ -30,6 +30,15 @@ describe('CLI run', function() {
     let fileResults;
 
     beforeAll(async () => {
+      try {
+        fs.symlinkSync(
+          `${LH_ROOT}/lighthouse-core/test/fixtures/config-plugins/lighthouse-plugin-simple`,
+          `${LH_ROOT}/lighthouse-plugin-simple`
+        );
+      } catch {
+        // Might exist already because process was killed before test finished.
+      }
+
       const url = 'http://localhost:10200/dobetterweb/dbw_tester.html';
       // eslint-disable-next-line max-len
       const samplev2ArtifactsPath = LH_ROOT + '/lighthouse-core/test/results/artifacts/';
@@ -38,8 +47,6 @@ describe('CLI run', function() {
       const flags = getFlags([
         '--output=json',
         `--output-path=${filename}`,
-        // Jest allows us to resolve this module with no setup.
-        // https://github.com/GoogleChrome/lighthouse/pull/13045#discussion_r708690607
         '--plugins=lighthouse-plugin-simple',
         // Use sample artifacts to avoid gathering during a unit test.
         `--audit-mode=${samplev2ArtifactsPath}`,
@@ -59,6 +66,7 @@ describe('CLI run', function() {
 
     afterAll(() => {
       fs.unlinkSync(filename);
+      fs.unlinkSync(`${LH_ROOT}/lighthouse-plugin-simple`);
     });
 
     it('returns results that match the saved results', () => {

lighthouse-core/test/gather/driver/execution-context-test.js

@@ -86,7 +86,7 @@ describe('ExecutionContext', () => {
     expect(executionContext.getContextId()).toEqual(undefined);
   });
 
-  it.todo('should cache native objects in page');
+  it.todo('TODO: should cache native objects in page');
 });
 
 describe('.evaluateAsync', () => {

lighthouse-core/test/jest-setup/setup.js

@@ -4,10 +4,25 @@
  * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
  */
 
-const {default: {toBeCloseTo}} = require('expect/build/matchers.js');
+const expect = require('expect');
 
 const format = require('../../../shared/localization/format.js');
 
+// TODO: the `message` value of these matchers seems to be ignored. Ex:
+//
+//        expect({a: 'A'}).toMatchObject({
+//          a: expect.toBeDisplayString('B'),
+//        });
+//
+// Error: expect(received).toMatchObject(expected)
+// - Expected  - 1
+// + Received  + 1
+//
+//   Object {
+// -   "a": toBeDisplayString<B>,
+// +   "a": "A",
+//   }
+
 expect.extend({
   toBeDisplayString(received, expected) {
     if (!format.isIcuMessage(received)) {
@@ -38,17 +53,31 @@ expect.extend({
 
     return {message, pass};
   },
+  toBeApproximately(received, expected, precision = 2) {
+    let pass = false;
+    let expectedDiff = 0;
+    let receivedDiff = 0;
+
+    if (received === Infinity && expected === Infinity) {
+      pass = true; // Infinity - Infinity is NaN
+    } else if (received === -Infinity && expected === -Infinity) {
+      pass = true; // -Infinity - -Infinity is NaN
+    } else {
+      expectedDiff = Math.pow(10, -precision) / 2;
+      receivedDiff = Math.abs(expected - received);
+      pass = receivedDiff < expectedDiff;
+    }
+
+    const message = () =>
+      [
+        `${this.utils.matcherHint('.toBeDisplayString')}\n`,
+        `Expected number to be close to:`,
+        `  ${this.utils.printExpected(expected)}`,
+        `Received:`,
+        `  ${this.utils.printReceived(received)}`,
+      ].join('\n');
 
-  // Expose toBeCloseTo() so it can be used as an asymmetric matcher.
-  toBeApproximately(...args) {
-    // If called asymmetrically, a fake matcher `this` object needs to be passed
-    // in (see https://github.com/facebook/jest/issues/8295). There's no effect
-    // because it's only used for the printing of full failures, which isn't
-    // done for asymmetric matchers anyways.
-    const thisObj = (this && this.utils) ? this :
-        {isNot: false, promise: ''};
-    // @ts-expect-error
-    return toBeCloseTo.call(thisObj, ...args);
+    return {message, pass};
   },
   /**
     * Asserts that an inspectable promise created by makePromiseInspectable is currently resolved or rejected.