From b6534053db81a9ac7d274b290e25ecce5f13020e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rub=C3=A9n=20Norte?= <rubennorte@fb.com>
Date: Wed, 20 Feb 2019 15:19:38 +0000
Subject: [PATCH] Ignore rootDir to determine the cache key of transformed
 files in babel-jest

---
 CHANGELOG.md                               |  1 +
 packages/babel-jest/package.json           |  1 +
 packages/babel-jest/src/__tests__/index.ts | 36 ++++++++++++++++++++
 packages/babel-jest/src/index.ts           | 38 +++++++++++++++++-----
 4 files changed, 68 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index bdf022c9ad6e..cc05844a801d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 - `[expect]`: Improve report when matcher fails, part 8 ([#7876](https://github.com/facebook/jest/pull/7876))
 - `[pretty-format]` Support `React.memo` ([#7891](https://github.com/facebook/jest/pull/7891))
 - `[jest-config]` Print error information on preset normalization error ([#7935](https://github.com/facebook/jest/pull/7935))
+- `[babel-jest]` Ignore `rootDir` to determine the cache key of transformed files ([#7947](https://github.com/facebook/jest/pull/7947))
 
 ### Fixes
 
diff --git a/packages/babel-jest/package.json b/packages/babel-jest/package.json
index 226e23853ce9..641e2f6d31a4 100644
--- a/packages/babel-jest/package.json
+++ b/packages/babel-jest/package.json
@@ -17,6 +17,7 @@
     "babel-plugin-istanbul": "^5.1.0",
     "babel-preset-jest": "^24.1.0",
     "chalk": "^2.4.2",
+    "jest-regex-util": "^24.0.0",
     "slash": "^2.0.0"
   },
   "devDependencies": {
diff --git a/packages/babel-jest/src/__tests__/index.ts b/packages/babel-jest/src/__tests__/index.ts
index 6b3d264a883f..a86b82ae2247 100644
--- a/packages/babel-jest/src/__tests__/index.ts
+++ b/packages/babel-jest/src/__tests__/index.ts
@@ -39,3 +39,39 @@ test(`Returns source string with inline maps when no transformOptions is passed`
   expect(result.map.sources).toEqual(['dummy_path.js']);
   expect(JSON.stringify(result.map.sourcesContent)).toMatch('customMultiply');
 });
+
+test('getCacheKey does not depend on the rootDir', () => {
+  const getCacheKeyArgs = rootDir => {
+    const config = {
+      cwd: rootDir,
+      rootDir,
+    };
+
+    return [
+      '// Some code',
+      `${rootDir}/foo/bar.js`,
+      JSON.stringify(config),
+      {config, instrument: true, rootDir: config.rootDir},
+    ];
+  };
+
+  jest.mock('@babel/core');
+
+  require('@babel/core').loadPartialConfig = options => ({
+    babelrc: `${options.cwd}/foo/.babelrc`,
+    config: `${options.cwd}/babel.config.js`,
+    options: {
+      cwd: options.cwd,
+      someOtherOption: `${options.cwd}/foo`,
+    },
+  });
+
+  const cacheKeyForRoot1 = babelJest.getCacheKey(
+    ...getCacheKeyArgs('/root1/dir'),
+  );
+  const cacheKeyForRoot2 = babelJest.getCacheKey(
+    ...getCacheKeyArgs('/root2/dir'),
+  );
+
+  expect(cacheKeyForRoot1).toEqual(cacheKeyForRoot2);
+});
diff --git a/packages/babel-jest/src/index.ts b/packages/babel-jest/src/index.ts
index 2df36fe37d22..12c3e5441ccb 100644
--- a/packages/babel-jest/src/index.ts
+++ b/packages/babel-jest/src/index.ts
@@ -17,6 +17,7 @@ import {
   transformSync as babelTransform,
 } from '@babel/core';
 import chalk from 'chalk';
+import {escapeStrForRegex} from 'jest-regex-util';
 import slash from 'slash';
 
 const THIS_FILE = fs.readFileSync(__filename);
@@ -65,33 +66,54 @@ const createTransformer = (
     return babelConfig;
   }
 
+  const rootDirRegExpCache: {[rootDir: string]: RegExp} = Object.create(null);
+
+  function getRootDirRegExp(rootDir: Config.Path): RegExp {
+    if (!rootDirRegExpCache[rootDir]) {
+      // "/path/to/root/dir" or
+      // "path/to/root/dir/inner
+      rootDirRegExpCache[rootDir] = new RegExp(
+        `(['"])${escapeStrForRegex(rootDir)}(\\1|${escapeStrForRegex(
+          path.sep,
+        )})`,
+        'g',
+      );
+    }
+
+    return rootDirRegExpCache[rootDir];
+  }
+
   const transformer: BabelJestTransformer = {
     canInstrument: true,
     createTransformer,
     getCacheKey(
       fileData,
       filename,
-      configString,
+      _configString,
       {config, instrument, rootDir},
     ) {
       const babelOptions = loadBabelConfig(config.cwd, filename);
-      const configPath = [
-        babelOptions.config || '',
-        babelOptions.babelrc || '',
-      ];
+      const configPath = [babelOptions.config, babelOptions.babelrc].map(
+        configPath => configPath && path.relative(rootDir, configPath),
+      );
 
       return crypto
         .createHash('md5')
         .update(THIS_FILE)
         .update('\0', 'utf8')
-        .update(JSON.stringify(babelOptions.options))
+        .update(
+          // Not pretty but not coupled to a specific signature of the
+          // babel options to relativize paths
+          JSON.stringify(babelOptions.options).replace(
+            getRootDirRegExp(rootDir),
+            '$1<rootDir>$2',
+          ),
+        )
         .update('\0', 'utf8')
         .update(fileData)
         .update('\0', 'utf8')
         .update(path.relative(rootDir, filename))
         .update('\0', 'utf8')
-        .update(configString)
-        .update('\0', 'utf8')
         .update(configPath.join(''))
         .update('\0', 'utf8')
         .update(instrument ? 'instrument' : '')