Fix code coverage for monorepos, facebook#4649

Author: bradfordlemley

packages/react-dev-utils/workspaceUtils.js

@@ -31,10 +31,11 @@ const findPkgs = (rootPath, globPatterns) => {
 
 const findMonorepo = appDir => {
   const monoPkgPath = findPkg.sync(path.resolve(appDir, '..'));
+  const monoRootPath = monoPkgPath && path.dirname(monoPkgPath);
   const monoPkg = monoPkgPath && require(monoPkgPath);
   const patterns = monoPkg && monoPkg.workspaces;
   const isYarnWs = Boolean(patterns);
-  const allPkgs = patterns && findPkgs(path.dirname(monoPkgPath), patterns);
+  const allPkgs = patterns && findPkgs(monoRootPath, patterns);
   const isIncluded = dir => allPkgs && allPkgs.indexOf(dir) !== -1;
   const isAppIncluded = isIncluded(appDir);
   const pkgs = allPkgs
@@ -45,6 +46,7 @@ const findMonorepo = appDir => {
     isAppIncluded,
     isYarnWs,
     pkgs,
+    rootPath: monoRootPath,
   };
 };
 

packages/react-scripts/config/paths.js

@@ -168,6 +168,8 @@ if (checkForMonorepo) {
   const mono = findMonorepo(appDirectory);
   if (mono.isAppIncluded) {
     Array.prototype.push.apply(module.exports.srcPaths, mono.pkgs);
+    module.exports.isMonorepo = true;
+    module.exports.monorepoRoot = mono.rootPath;
   }
   module.exports.useYarn = module.exports.useYarn || mono.isYarnWs;
 }

packages/react-scripts/scripts/eject.js

@@ -107,7 +107,7 @@ inquirer
 
     // Prepare Jest config early in case it throws
     const jestConfig = createJestConfig(
-      filePath => path.posix.join('<rootDir>', filePath),
+      filePath => path.posix.join('.', filePath),
       null,
       paths.srcPaths
     );

packages/react-scripts/scripts/utils/createJestConfig.js

@@ -15,27 +15,31 @@ const paths = require('../../config/paths');
 module.exports = (resolve, rootDir, srcRoots) => {
   // Use this instead of `paths.testsSetup` to avoid putting
   // an absolute filename into configuration after ejecting.
+  if (paths.isMonorepo) {
+    rootDir = paths.monorepoRoot;
+  }
+
+  const toRelRootDir = f => '<rootDir>/' + path.relative(rootDir || '', f);
+
   const setupTestsMatches = paths.testsSetup.match(/src\/setupTests\.(.+)/);
   const setupTestsFileExtension =
     (setupTestsMatches && setupTestsMatches[1]) || 'js';
   const setupTestsFile = fs.existsSync(paths.testsSetup)
-    ? `<rootDir>/src/setupTests.${setupTestsFileExtension}`
+    ? toRelRootDir(`src/setupTests.${setupTestsFileExtension}`)
     : undefined;
 
-  const toRelRootDir = f => '<rootDir>/' + path.relative(rootDir || '', f);
-
   // TODO: I don't know if it's safe or not to just use / as path separator
   // in Jest configs. We need help from somebody with Windows to determine this.
   const config = {
-    collectCoverageFrom: ['src/**/*.{js,jsx,ts,tsx}', '!src/**/*.d.ts'],
-
+    collectCoverageFrom: srcRoots
+      .map(root => path.join(toRelRootDir(root), '**/*.{js,jsx,ts,tsx}'))
+      .concat(['!**/build*/**', '!**/coverage*/**', '!**/*.d.ts']),
     // TODO: this breaks Yarn PnP on eject.
     // But we can't simply emit this because it'll be an absolute path.
     // The proper fix is to write jest.config.js on eject instead of a package.json key.
     // Then these can always stay as require.resolve()s.
     resolver: require.resolve('jest-pnp-resolver'),
     setupFiles: [require.resolve('react-app-polyfill/jsdom')],
-
     setupTestFrameworkScriptFile: setupTestsFile,
     testMatch: [
       '**/__tests__/**/*.{js,jsx,ts,tsx}',