Transformer configs (#7288)

CHANGELOG.md

@@ -9,6 +9,7 @@
 - `[*]` Manage the global timeout with `--testTimeout` command line argument. ([#8456](https://github.com/facebook/jest/pull/8456))
 - `[pretty-format]` Render custom displayName of memoized components
 - `[jest-validate]` Allow `maxWorkers` as part of the `jest.config.js` ([#8565](https://github.com/facebook/jest/pull/8565))
+- `[jest-runtime]` Allow passing configuration objects to transformers ([#7288](https://github.com/facebook/jest/pull/7288))
 
 ### Fixes
 

docs/Configuration.md

@@ -1072,14 +1072,16 @@ Default: `real`
 
 Setting this value to `fake` allows the use of fake timers for functions such as `setTimeout`. Fake timers are useful when a piece of code sets a long timeout that we don't want to wait for in a test.
 
-### `transform` [object<string, string>]
+### `transform` [object<string, pathToTransformer | [pathToTransformer, object]>]
 
 Default: `undefined`
 
 A map from regular expressions to paths to transformers. A transformer is a module that provides a synchronous function for transforming source files. For example, if you wanted to be able to use a new language feature in your modules or tests that isn't yet supported by node, you might plug in one of many compilers that compile a future version of JavaScript to a current one. Example: see the [examples/typescript](https://github.com/facebook/jest/blob/master/examples/typescript/package.json#L16) example or the [webpack tutorial](Webpack.md).
 
 Examples of such compilers include [Babel](https://babeljs.io/), [TypeScript](http://www.typescriptlang.org/) and [async-to-gen](http://github.com/leebyron/async-to-gen#jest).
 
+You can pass configuration to a transformer like `{filePattern: ['path-to-transformer', {options}]}` For example, to configure babel-jest for non-default behavior, `{"\\.js$": ['babel-jest', {rootMode: "upward"}]}`
+
 _Note: a transformer is only run once per file unless the file has changed. During development of a transformer it can be useful to run Jest with `--no-cache` to frequently [delete Jest's cache](Troubleshooting.md#caching-issues)._
 
 _Note: if you are using the `babel-jest` transformer and want to use an additional code preprocessor, keep in mind that when "transform" is overwritten in any way the `babel-jest` is not loaded automatically anymore. If you want to use it to compile JavaScript code it has to be explicitly defined. See [babel-jest plugin](https://github.com/facebook/jest/tree/master/packages/babel-jest#setup)_

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

@@ -35,3 +35,12 @@ All files   |    83.33 |      100 |       50 |       80 |                   |
 ------------|----------|----------|----------|----------|-------------------|
 
 `;
+
+exports[`transformer-config instruments only specific files and collects coverage 1`] = `
+"------------|----------|----------|----------|----------|-------------------|
+File        |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
+------------|----------|----------|----------|----------|-------------------|
+All files   |    83.33 |      100 |       50 |       80 |                   |
+ Covered.js |    83.33 |      100 |       50 |       80 |                13 |
+------------|----------|----------|----------|----------|-------------------|"
+`;

e2e/__tests__/transform.test.ts

@@ -159,3 +159,29 @@ describe('ecmascript-modules-support', () => {
     expect(json.numTotalTests).toBeGreaterThanOrEqual(1);
   });
 });
+
+describe('transformer-config', () => {
+  const dir = path.resolve(__dirname, '..', 'transform/transformer-config');
+
+  beforeEach(() => {
+    run('yarn', dir);
+  });
+
+  it('runs transpiled code', () => {
+    // --no-cache because babel can cache stuff and result in false green
+    const {json} = runWithJson(dir, ['--no-cache']);
+    expect(json.success).toBe(true);
+    expect(json.numTotalTests).toBeGreaterThanOrEqual(1);
+  });
+
+  it('instruments only specific files and collects coverage', () => {
+    const {stdout} = runJest(dir, ['--coverage', '--no-cache'], {
+      stripAnsi: true,
+    });
+    expect(stdout).toMatch('Covered.js');
+    expect(stdout).not.toMatch('NotCovered.js');
+    expect(stdout).not.toMatch('ExcludedFromCoverage.js');
+    // coverage result should not change
+    expect(stdout).toMatchSnapshot();
+  });
+});

e2e/transform/transformer-config/.babelrc

@@ -0,0 +1 @@
+{}

e2e/transform/transformer-config/NotCovered.js

@@ -0,0 +1,12 @@
+/**
+ * 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.
+ */
+
+const thisFunctionIsNeverInstrumented = () => null;
+
+module.exports = {
+  thisFunctionIsNeverInstrumented,
+};

e2e/transform/transformer-config/__tests__/transformer-config.test.js

@@ -0,0 +1,15 @@
+/**
+ * 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.
+ */
+
+'use strict';
+
+require('../this-directory-is-covered/ExcludedFromCoverage');
+
+it('strips flowtypes using babel-jest and config passed to transformer', () => {
+  const a: string = 'a';
+  expect(a).toBe('a');
+});

e2e/transform/transformer-config/package.json

@@ -0,0 +1,25 @@
+{
+  "dependencies": {
+    "@babel/preset-flow": "7.0.0"
+  },
+  "jest": {
+    "collectCoverageOnlyFrom": {
+      "<rootDir>/this-directory-is-covered/Covered.js": true,
+      "<rootDir>/this-directory-is-covered/ExcludedFromCoverage.js": true
+    },
+    "coveragePathIgnorePatterns": [
+      "ExcludedFromCoverage"
+    ],
+    "testEnvironment": "node",
+    "transform": {
+      "\\.js$": [
+        "babel-jest",
+        {
+          "presets": [
+            "@babel/preset-flow"
+          ]
+        }
+      ]
+    }
+  }
+}

e2e/transform/transformer-config/this-directory-is-covered/Covered.js

@@ -0,0 +1,19 @@
+/**
+ * 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.
+ */
+
+const thisFunctionIsCovered = (): null => null;
+
+thisFunctionIsCovered();
+
+const thisFunctionIsNotCovered = (): void => {
+  throw new Error('Never Called');
+};
+
+module.exports = {
+  thisFunctionIsCovered,
+  thisFunctionIsNotCovered,
+};

e2e/transform/transformer-config/this-directory-is-covered/ExcludedFromCoverage.js

@@ -0,0 +1,15 @@
+/**
+ * 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.
+ */
+
+require('./Covered');
+require('../NotCovered');
+
+const thisFunctionIsNeverInstrumented = () => null;
+
+module.exports = {
+  thisFunctionIsNeverInstrumented,
+};

e2e/transform/transformer-config/yarn.lock

@@ -0,0 +1,34 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+babel-plugin-syntax-flow@^6.8.0:
+  version "6.18.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-syntax-flow/-/babel-plugin-syntax-flow-6.18.0.tgz#4c3ab20a2af26aa20cd25995c398c4eb70310c8d"
+  integrity sha1-TDqyCiryaqIM0lmVw5jE63AxDI0=
+
+babel-plugin-transform-flow-strip-types@6.8.0:
+  version "6.8.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-transform-flow-strip-types/-/babel-plugin-transform-flow-strip-types-6.8.0.tgz#2351d85e3a52152e1a55d3f08ae635e21ece17a0"
+  integrity sha1-I1HYXjpSFS4aVdPwiuY14h7OF6A=
+  dependencies:
+    babel-plugin-syntax-flow "^6.8.0"
+    babel-runtime "^6.0.0"
+
+babel-runtime@^6.0.0:
+  version "6.23.0"
+  resolved "https://registry.yarnpkg.com/babel-runtime/-/babel-runtime-6.23.0.tgz#0a9489f144de70efb3ce4300accdb329e2fc543b"
+  integrity sha1-CpSJ8UTecO+zzkMArM2zKeL8VDs=
+  dependencies:
+    core-js "^2.4.0"
+    regenerator-runtime "^0.10.0"
+
+core-js@^2.4.0:
+  version "2.4.1"
+  resolved "https://registry.yarnpkg.com/core-js/-/core-js-2.4.1.tgz#4de911e667b0eae9124e34254b53aea6fc618d3e"
+  integrity sha1-TekR5mew6ukSTjQlS1OupvxhjT4=
+
+regenerator-runtime@^0.10.0:
+  version "0.10.4"
+  resolved "https://registry.yarnpkg.com/regenerator-runtime/-/regenerator-runtime-0.10.4.tgz#74cb6598d3ba2eb18694e968a40e2b3b4df9cf93"
+  integrity sha1-dMtlmNO6LrGGlOlopA4rO035z5M=

packages/jest-config/src/__tests__/normalize.test.js

@@ -331,6 +331,24 @@ describe('transform', () => {
       ['abs-path', '/qux/quux'],
     ]);
   });
+  it("pulls in config if it's passed as an array", () => {
+    const {options} = normalize(
+      {
+        rootDir: '/root/',
+        transform: {
+          [DEFAULT_CSS_PATTERN]: '<rootDir>/node_modules/jest-regex-util',
+          [DEFAULT_JS_PATTERN]: ['babel-jest', {rootMode: 'upward'}],
+          'abs-path': '/qux/quux',
+        },
+      },
+      {},
+    );
+    expect(options.transform).toEqual([
+      [DEFAULT_CSS_PATTERN, '/root/node_modules/jest-regex-util'],
+      [DEFAULT_JS_PATTERN, require.resolve('babel-jest'), {rootMode: 'upward'}],
+      ['abs-path', '/qux/quux'],
+    ]);
+  });
 });
 
 describe('haste', () => {

packages/jest-config/src/normalize.ts

@@ -46,19 +46,29 @@ type AllOptions = Config.ProjectConfig & Config.GlobalConfig;
 const createConfigError = (message: string) =>
   new ValidationError(ERROR, message, DOCUMENTATION_NOTE);
 
-const mergeOptionWithPreset = (
+// TS 3.5 forces us to split these into 2
+const mergeModuleNameMapperWithPreset = (
+  options: Config.InitialOptions,
+  preset: Config.InitialOptions,
+) => {
+  if (options['moduleNameMapper'] && preset['moduleNameMapper']) {
+    options['moduleNameMapper'] = {
+      ...options['moduleNameMapper'],
+      ...preset['moduleNameMapper'],
+      ...options['moduleNameMapper'],
+    };
+  }
+};
+
+const mergeTransformWithPreset = (
   options: Config.InitialOptions,
   preset: Config.InitialOptions,
-  optionName: keyof Pick<
-    Config.InitialOptions,
-    'moduleNameMapper' | 'transform'
-  >,
 ) => {
-  if (options[optionName] && preset[optionName]) {
-    options[optionName] = {
-      ...options[optionName],
-      ...preset[optionName],
-      ...options[optionName],
+  if (options['transform'] && preset['transform']) {
+    options['transform'] = {
+      ...options['transform'],
+      ...preset['transform'],
+      ...options['transform'],
     };
   }
 };
@@ -121,8 +131,8 @@ const setupPreset = (
       options.modulePathIgnorePatterns,
     );
   }
-  mergeOptionWithPreset(options, preset, 'moduleNameMapper');
-  mergeOptionWithPreset(options, preset, 'transform');
+  mergeModuleNameMapperWithPreset(options, preset);
+  mergeTransformWithPreset(options, preset);
 
   return {...preset, ...options};
 };
@@ -140,27 +150,26 @@ const setupBabelJest = (options: Config.InitialOptions) => {
       return regex.test('a.ts') || regex.test('a.tsx');
     });
 
-    if (customJSPattern) {
-      const customJSTransformer = transform[customJSPattern];
-
-      if (customJSTransformer === 'babel-jest') {
-        babelJest = require.resolve('babel-jest');
-        transform[customJSPattern] = babelJest;
-      } else if (customJSTransformer.includes('babel-jest')) {
-        babelJest = customJSTransformer;
-      }
-    }
-
-    if (customTSPattern) {
-      const customTSTransformer = transform[customTSPattern];
-
-      if (customTSTransformer === 'babel-jest') {
-        babelJest = require.resolve('babel-jest');
-        transform[customTSPattern] = babelJest;
-      } else if (customTSTransformer.includes('babel-jest')) {
-        babelJest = customTSTransformer;
+    [customJSPattern, customTSPattern].forEach(pattern => {
+      if (pattern) {
+        const customTransformer = transform[pattern];
+        if (Array.isArray(customTransformer)) {
+          if (customTransformer[0] === 'babel-jest') {
+            babelJest = require.resolve('babel-jest');
+            customTransformer[0] = babelJest;
+          } else if (customTransformer[0].includes('babel-jest')) {
+            babelJest = customTransformer[0];
+          }
+        } else {
+          if (customTransformer === 'babel-jest') {
+            babelJest = require.resolve('babel-jest');
+            transform[pattern] = babelJest;
+          } else if (customTransformer.includes('babel-jest')) {
+            babelJest = customTransformer;
+          }
+        }
       }
-    }
+    });
   } else {
     babelJest = require.resolve('babel-jest');
     options.transform = {
@@ -620,14 +629,20 @@ export default function normalize(
         const transform = oldOptions[key];
         value =
           transform &&
-          Object.keys(transform).map(regex => [
-            regex,
-            resolve(newOptions.resolver, {
-              filePath: transform[regex],
-              key,
-              rootDir: options.rootDir,
-            }),
-          ]);
+          Object.keys(transform).map(regex => {
+            const transformElement = transform[regex];
+            return [
+              regex,
+              resolve(newOptions.resolver, {
+                filePath: Array.isArray(transformElement)
+                  ? transformElement[0]
+                  : transformElement,
+                key,
+                rootDir: options.rootDir,
+              }),
+              ...(Array.isArray(transformElement) ? [transformElement[1]] : []),
+            ];
+          });
         break;
       case 'coveragePathIgnorePatterns':
       case 'modulePathIgnorePatterns':