Show coverage of sources related to tests in changed files (#9769)

* Add findRelatdSourcesFromTestsInChangedFiles in SearchSource

* check sourcesRelatedToTestsInChangedFiles in shouldInstrument

* Add tests for findRelatedSourcesFromTestsInChangedFiles

* Update CHANGELOG.md

* Address code review suggestion

* Use hasSCM utility in SearchSource.findTestRelatedToChangeFiles

* Create searchSources at first for reuse in runJest

* Create and keep DependencyResolver in SearchSource for reuse

* Address code review suggestion

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Features
 
 - `[@jest/globals]` New package so Jest's globals can be explicitly imported ([#9801](https://github.com/facebook/jest/pull/9801))
+- `[jest-core]` Show coverage of sources related to tests in changed files ([#9769](https://github.com/facebook/jest/pull/9769))
 - `[jest-runtime]` Populate `require.cache` ([#9841](https://github.com/facebook/jest/pull/9841))
 
 ### Fixes

e2e/__tests__/onlyChanged.test.ts

@@ -137,6 +137,39 @@ test('report test coverage for only changed files', () => {
   expect(stdout).not.toMatch('b.js');
 });
 
+test('report test coverage of source on test file change under only changed files', () => {
+  writeFiles(DIR, {
+    '__tests__/a.test.js': `
+    require('../a');
+    test('a1', () => expect(1).toBe(1));
+  `,
+    'a.js': 'module.exports = {}',
+    'package.json': JSON.stringify({
+      jest: {
+        collectCoverage: true,
+        coverageReporters: ['text'],
+        testEnvironment: 'node',
+      },
+    }),
+  });
+
+  run(`${GIT} init`, DIR);
+  run(`${GIT} add .`, DIR);
+  run(`${GIT} commit --no-gpg-sign -m "first"`, DIR);
+
+  writeFiles(DIR, {
+    '__tests__/a.test.js': `
+    require('../a');
+    test('a1', () => expect(1).toBe(1));
+    test('a2', () => expect(2).toBe(2));
+  `,
+  });
+
+  const {stdout} = runJest(DIR, ['--only-changed']);
+
+  expect(stdout).toMatch('a.js');
+});
+
 test('do not pickup non-tested files when reporting coverage on only changed files', () => {
   writeFiles(DIR, {
     'a.js': 'module.exports = {}',

packages/jest-core/src/SearchSource.ts

@@ -51,13 +51,22 @@ const toTests = (context: Context, tests: Array<Config.Path>) =>
     path,
   }));
 
+const hasSCM = (changedFilesInfo: ChangedFiles) => {
+  const {repos} = changedFilesInfo;
+  // no SCM (git/hg/...) is found in any of the roots.
+  const noSCM = Object.values(repos).every(scm => scm.size === 0);
+  return !noSCM;
+};
+
 export default class SearchSource {
   private _context: Context;
+  private _dependencyResolver: DependencyResolver | null;
   private _testPathCases: TestPathCases = [];
 
   constructor(context: Context) {
     const {config} = context;
     this._context = context;
+    this._dependencyResolver = null;
 
     const rootPattern = new RegExp(
       config.roots.map(dir => escapePathForRegex(dir + path.sep)).join('|'),
@@ -92,6 +101,17 @@ export default class SearchSource {
     }
   }
 
+  private _getOrBuildDependencyResolver(): DependencyResolver {
+    if (!this._dependencyResolver) {
+      this._dependencyResolver = new DependencyResolver(
+        this._context.resolver,
+        this._context.hasteFS,
+        buildSnapshotResolver(this._context.config),
+      );
+    }
+    return this._dependencyResolver;
+  }
+
   private _filterTestPathsWithStats(
     allPaths: Array<Test>,
     testPathPattern?: string,
@@ -155,11 +175,7 @@ export default class SearchSource {
     allPaths: Set<Config.Path>,
     collectCoverage: boolean,
   ): SearchResult {
-    const dependencyResolver = new DependencyResolver(
-      this._context.resolver,
-      this._context.hasteFS,
-      buildSnapshotResolver(this._context.config),
-    );
+    const dependencyResolver = this._getOrBuildDependencyResolver();
 
     if (!collectCoverage) {
       return {
@@ -240,14 +256,11 @@ export default class SearchSource {
     changedFilesInfo: ChangedFiles,
     collectCoverage: boolean,
   ): SearchResult {
-    const {repos, changedFiles} = changedFilesInfo;
-    // no SCM (git/hg/...) is found in any of the roots.
-    const noSCM = (Object.keys(repos) as Array<
-      keyof ChangedFiles['repos']
-    >).every(scm => repos[scm].size === 0);
-    return noSCM
-      ? {noSCM: true, tests: []}
-      : this.findRelatedTests(changedFiles, collectCoverage);
+    if (!hasSCM(changedFilesInfo)) {
+      return {noSCM: true, tests: []};
+    }
+    const {changedFiles} = changedFilesInfo;
+    return this.findRelatedTests(changedFiles, collectCoverage);
   }
 
   private _getTestPaths(
@@ -328,4 +341,24 @@ export default class SearchSource {
 
     return searchResult;
   }
+
+  findRelatedSourcesFromTestsInChangedFiles(
+    changedFilesInfo: ChangedFiles,
+  ): Array<string> {
+    if (!hasSCM(changedFilesInfo)) {
+      return [];
+    }
+    const {changedFiles} = changedFilesInfo;
+    const dependencyResolver = this._getOrBuildDependencyResolver();
+    const relatedSourcesSet = new Set<string>();
+    changedFiles.forEach(filePath => {
+      if (this.isTestFilePath(filePath)) {
+        const sourcePaths = dependencyResolver.resolve(filePath, {
+          skipNodeResolution: this._context.config.skipNodeResolution,
+        });
+        sourcePaths.forEach(sourcePath => relatedSourcesSet.add(sourcePath));
+      }
+    });
+    return Array.from(relatedSourcesSet);
+  }
 }

packages/jest-core/src/TestScheduler.ts

@@ -44,6 +44,7 @@ export type TestSchedulerContext = {
   firstRun: boolean;
   previousSuccess: boolean;
   changedFiles?: Set<Config.Path>;
+  sourcesRelatedToTestsInChangedFiles?: Set<Config.Path>;
 };
 export default class TestScheduler {
   private _dispatcher: ReporterDispatcher;
@@ -180,7 +181,9 @@ export default class TestScheduler {
       if (!testRunners[config.runner]) {
         const Runner: typeof TestRunner = require(config.runner);
         testRunners[config.runner] = new Runner(this._globalConfig, {
-          changedFiles: this._context && this._context.changedFiles,
+          changedFiles: this._context?.changedFiles,
+          sourcesRelatedToTestsInChangedFiles: this._context
+            ?.sourcesRelatedToTestsInChangedFiles,
         });
       }
     });
@@ -272,7 +275,9 @@ export default class TestScheduler {
     if (!isDefault && collectCoverage) {
       this.addReporter(
         new CoverageReporter(this._globalConfig, {
-          changedFiles: this._context && this._context.changedFiles,
+          changedFiles: this._context?.changedFiles,
+          sourcesRelatedToTestsInChangedFiles: this._context
+            ?.sourcesRelatedToTestsInChangedFiles,
         }),
       );
     }
@@ -302,7 +307,9 @@ export default class TestScheduler {
     if (collectCoverage) {
       this.addReporter(
         new CoverageReporter(this._globalConfig, {
-          changedFiles: this._context && this._context.changedFiles,
+          changedFiles: this._context?.changedFiles,
+          sourcesRelatedToTestsInChangedFiles: this._context
+            ?.sourcesRelatedToTestsInChangedFiles,
         }),
       );
     }

packages/jest-core/src/__tests__/SearchSource.test.ts

@@ -531,4 +531,64 @@ describe('SearchSource', () => {
       }
     });
   });
+
+  describe('findRelatedSourcesFromTestsInChangedFiles', () => {
+    const rootDir = path.resolve(
+      __dirname,
+      '../../../jest-runtime/src/__tests__/test_root',
+    );
+
+    beforeEach(async () => {
+      const {options: config} = normalize(
+        {
+          haste: {
+            hasteImplModulePath: path.resolve(
+              __dirname,
+              '../../../jest-haste-map/src/__tests__/haste_impl.js',
+            ),
+            providesModuleNodeModules: [],
+          },
+          name: 'SearchSource-findRelatedSourcesFromTestsInChangedFiles-tests',
+          rootDir,
+        },
+        {} as Config.Argv,
+      );
+      const context = await Runtime.createContext(config, {
+        maxWorkers,
+        watchman: false,
+      });
+      searchSource = new SearchSource(context);
+    });
+
+    it('return empty set if no SCM', () => {
+      const requireRegularModule = path.join(
+        rootDir,
+        'RequireRegularModule.js',
+      );
+      const sources = searchSource.findRelatedSourcesFromTestsInChangedFiles({
+        changedFiles: new Set([requireRegularModule]),
+        repos: {
+          git: new Set(),
+          hg: new Set(),
+        },
+      });
+      expect(sources).toEqual([]);
+    });
+
+    it('return sources required by tests', () => {
+      const regularModule = path.join(rootDir, 'RegularModule.js');
+      const requireRegularModule = path.join(
+        rootDir,
+        'RequireRegularModule.js',
+      );
+      const sources = searchSource.findRelatedSourcesFromTestsInChangedFiles({
+        changedFiles: new Set([requireRegularModule]),
+        repos: {
+          git: new Set('/path/to/git'),
+          hg: new Set(),
+        },
+      });
+      expect(sources).toEqual([regularModule]);
+    });
+  });
 });

packages/jest-core/src/runJest.ts

@@ -34,13 +34,12 @@ import type {Filter, TestRunData} from './types';
 
 const getTestPaths = async (
   globalConfig: Config.GlobalConfig,
-  context: Context,
+  source: SearchSource,
   outputStream: NodeJS.WriteStream,
   changedFiles: ChangedFiles | undefined,
   jestHooks: JestHookEmitter,
   filter?: Filter,
 ) => {
-  const source = new SearchSource(context);
   const data = await source.getTestPaths(globalConfig, changedFiles, filter);
 
   if (!data.tests.length && globalConfig.onlyChanged && data.noSCM) {
@@ -167,11 +166,14 @@ export default async function runJest({
     }
   }
 
+  const searchSources = contexts.map(context => new SearchSource(context));
+
   const testRunData: TestRunData = await Promise.all(
-    contexts.map(async context => {
+    contexts.map(async (context, index) => {
+      const searchSource = searchSources[index];
       const matches = await getTestPaths(
         globalConfig,
-        context,
+        searchSource,
         outputStream,
         changedFilesPromise && (await changedFilesPromise),
         jestHooks,
@@ -242,9 +244,22 @@ export default async function runJest({
   }
 
   if (changedFilesPromise) {
-    testSchedulerContext.changedFiles = (
-      await changedFilesPromise
-    ).changedFiles;
+    const changedFilesInfo = await changedFilesPromise;
+    if (changedFilesInfo.changedFiles) {
+      testSchedulerContext.changedFiles = changedFilesInfo.changedFiles;
+      const sourcesRelatedToTestsInChangedFilesArray = contexts
+        .map((_, index) => {
+          const searchSource = searchSources[index];
+          const relatedSourceFromTestsInChangedFiles = searchSource.findRelatedSourcesFromTestsInChangedFiles(
+            changedFilesInfo,
+          );
+          return relatedSourceFromTestsInChangedFiles;
+        })
+        .reduce((total, paths) => total.concat(paths), []);
+      testSchedulerContext.sourcesRelatedToTestsInChangedFiles = new Set(
+        sourcesRelatedToTestsInChangedFilesArray,
+      );
+    }
   }
 
   const results = await new TestScheduler(

packages/jest-reporters/src/__tests__/coverage_worker.test.js

@@ -41,6 +41,7 @@ test('resolves to the result of generateEmptyCoverage upon success', async () =>
     globalConfig,
     config,
     undefined,
+    undefined,
   );
 
   expect(result).toEqual(42);

packages/jest-reporters/src/coverage_reporter.ts

@@ -182,6 +182,9 @@ export default class CoverageReporter extends BaseReporter {
               changedFiles:
                 this._options.changedFiles &&
                 Array.from(this._options.changedFiles),
+              sourcesRelatedToTestsInChangedFiles:
+                this._options.sourcesRelatedToTestsInChangedFiles &&
+                Array.from(this._options.sourcesRelatedToTestsInChangedFiles),
             },
             path: filename,
           });

packages/jest-reporters/src/coverage_worker.ts

@@ -40,6 +40,8 @@ export function worker({
     path,
     globalConfig,
     config,
-    options && options.changedFiles && new Set(options.changedFiles),
+    options?.changedFiles && new Set(options.changedFiles),
+    options?.sourcesRelatedToTestsInChangedFiles &&
+      new Set(options.sourcesRelatedToTestsInChangedFiles),
   );
 }

packages/jest-reporters/src/generateEmptyCoverage.ts

@@ -30,13 +30,15 @@ export default function (
   globalConfig: Config.GlobalConfig,
   config: Config.ProjectConfig,
   changedFiles?: Set<Config.Path>,
+  sourcesRelatedToTestsInChangedFiles?: Set<Config.Path>,
 ): CoverageWorkerResult | null {
   const coverageOptions = {
     changedFiles,
     collectCoverage: globalConfig.collectCoverage,
     collectCoverageFrom: globalConfig.collectCoverageFrom,
     collectCoverageOnlyFrom: globalConfig.collectCoverageOnlyFrom,
     coverageProvider: globalConfig.coverageProvider,
+    sourcesRelatedToTestsInChangedFiles,
   };
   let coverageWorkerResult: CoverageWorkerResult | null = null;
   if (shouldInstrument(filename, coverageOptions, config)) {

packages/jest-reporters/src/types.ts

@@ -37,10 +37,12 @@ export type CoverageWorker = {worker: typeof worker};
 
 export type CoverageReporterOptions = {
   changedFiles?: Set<Config.Path>;
+  sourcesRelatedToTestsInChangedFiles?: Set<Config.Path>;
 };
 
 export type CoverageReporterSerializedOptions = {
   changedFiles?: Array<Config.Path>;
+  sourcesRelatedToTestsInChangedFiles?: Array<Config.Path>;
 };
 
 export type OnTestStart = (test: Test) => Promise<void>;

packages/jest-runner/src/runTest.ts

@@ -147,11 +147,13 @@ async function runTestInternal(
   setGlobal(environment.global, 'console', testConsole);
 
   const runtime = new Runtime(config, environment, resolver, cacheFS, {
-    changedFiles: context && context.changedFiles,
+    changedFiles: context?.changedFiles,
     collectCoverage: globalConfig.collectCoverage,
     collectCoverageFrom: globalConfig.collectCoverageFrom,
     collectCoverageOnlyFrom: globalConfig.collectCoverageOnlyFrom,
     coverageProvider: globalConfig.coverageProvider,
+    sourcesRelatedToTestsInChangedFiles:
+      context?.sourcesRelatedToTestsInChangedFiles,
   });
 
   const start = Date.now();

packages/jest-runner/src/types.ts

@@ -51,6 +51,7 @@ export type TestRunnerOptions = {
 
 export type TestRunnerContext = {
   changedFiles?: Set<Config.Path>;
+  sourcesRelatedToTestsInChangedFiles?: Set<Config.Path>;
 };
 
 export type TestRunnerSerializedContext = {

packages/jest-runtime/src/index.ts

@@ -171,6 +171,7 @@ class Runtime {
       collectCoverageFrom: [],
       collectCoverageOnlyFrom: undefined,
       coverageProvider: 'babel',
+      sourcesRelatedToTestsInChangedFiles: undefined,
     };
     this._currentlyExecutingModulePath = '';
     this._environment = environment;