[jest-resolve] Add async resolver support (#11540)

Co-authored-by: Simen Bekkhus <sbekkhus91@gmail.com>

CHANGELOG.md

@@ -16,6 +16,7 @@
 - `[jest-mock]` Improve `isMockFunction` to infer types of passed function ([#12442](https://github.com/facebook/jest/pull/12442))
 - `[jest-resolve]` [**BREAKING**] Add support for `package.json` `exports` ([#11961](https://github.com/facebook/jest/pull/11961), [#12373](https://github.com/facebook/jest/pull/12373))
 - `[jest-resolve, jest-runtime]` Add support for `data:` URI import and mock ([#12392](https://github.com/facebook/jest/pull/12392))
+- `[jest-resolve, jest-runtime]` Add support for async resolver ([#11540](https://github.com/facebook/jest/pull/11540))
 - `[@jest/schemas]` New module for JSON schemas for Jest's config ([#12384](https://github.com/facebook/jest/pull/12384))
 - `[jest-worker]` [**BREAKING**] Allow only absolute `workerPath` ([#12343](https://github.com/facebook/jest/pull/12343))
 - `[pretty-format]` New `maxWidth` parameter ([#12402](https://github.com/facebook/jest/pull/12402))

docs/Configuration.md

@@ -779,13 +779,18 @@ By default, each test file gets its own independent module registry. Enabling `r
 
 Default: `undefined`
 
-This option allows the use of a custom resolver. This resolver must be a node module that exports a function expecting a string as the first argument for the path to resolve and an object with the following structure as the second argument:
+This option allows the use of a custom resolver. This resolver must be a node module that exports _either_:
+
+1. a function expecting a string as the first argument for the path to resolve and an options object as the second argument. The function should either return a path to the module that should be resolved or throw an error if the module can't be found. _or_
+2. an object containing `async` and/or `sync` properties. The `sync` property should be a function with the shape explained above, and the `async` property should also be a function that accepts the same arguments, but returns a promise which resolves with the path to the module or rejects with an error.
+
+The options object provided to resolvers has the shape:
 
 ```json
 {
   "basedir": string,
   "conditions": [string],
-  "defaultResolver": "function(request, options)",
+  "defaultResolver": "function(request, options) -> string",
   "extensions": [string],
   "moduleDirectory": [string],
   "paths": [string],
@@ -795,9 +800,7 @@ This option allows the use of a custom resolver. This resolver must be a node mo
 }
 ```
 
-The function should either return a path to the module that should be resolved or throw an error if the module can't be found.
-
-Note: the defaultResolver passed as an option is the Jest default resolver which might be useful when you write your custom one. It takes the same arguments as your custom one, e.g. `(request, options)`.
+Note: the `defaultResolver` passed as an option is the Jest default resolver which might be useful when you write your custom one. It takes the same arguments as your custom synchronous one, e.g. `(request, options)` and returns a string or throws.
 
 For example, if you want to respect Browserify's [`"browser"` field](https://github.com/browserify/browserify-handbook/blob/master/readme.markdown#browser-field), you can use the following configuration:
 

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

@@ -41,7 +41,7 @@ exports[`moduleNameMapper wrong array configuration 1`] = `
       12 | module.exports = () => 'test';
       13 |
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:572:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:897:17)
       at Object.require (index.js:10:1)"
 `;
 
@@ -70,6 +70,6 @@ exports[`moduleNameMapper wrong configuration 1`] = `
       12 | module.exports = () => 'test';
       13 |
 
-      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:572:17)
+      at createNoMappedModuleFoundError (../../packages/jest-resolve/build/resolver.js:897:17)
       at Object.require (index.js:10:1)"
 `;

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

@@ -0,0 +1,9 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`on node >=12.16.0 runs test with native ESM 1`] = `
+"Test Suites: 1 passed, 1 total
+Tests:       1 passed, 1 total
+Snapshots:   0 total
+Time:        <<REPLACED>>
+Ran all test suites."
+`;

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

@@ -37,6 +37,6 @@ exports[`show error message with matching files 1`] = `
         |                  ^
       9 |
 
-      at Resolver.resolveModule (../../packages/jest-resolve/build/resolver.js:317:11)
+      at Resolver._throwModNotFoundError (../../packages/jest-resolve/build/resolver.js:491:11)
       at Object.require (index.js:8:18)"
 `;

e2e/__tests__/resolveAsync.test.ts

@@ -0,0 +1,25 @@
+/**
+ * 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.
+ */
+
+import {onNodeVersions} from '@jest/test-utils';
+import {extractSummary} from '../Utils';
+import runJest from '../runJest';
+
+// The versions where vm.Module exists and commonjs with "exports" is not broken
+onNodeVersions('>=12.16.0', () => {
+  test('runs test with native ESM', () => {
+    const {exitCode, stderr, stdout} = runJest('resolve-async', [], {
+      nodeOptions: '--experimental-vm-modules --no-warnings',
+    });
+
+    const {summary} = extractSummary(stderr);
+
+    expect(summary).toMatchSnapshot();
+    expect(stdout).toBe('');
+    expect(exitCode).toBe(0);
+  });
+});

e2e/resolve-async/__tests__/resolveAsync.test.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.
+ */
+
+import greeting from '../some-file';
+
+test('async resolver resolves to correct file', () => {
+  expect(greeting).toEqual('Hello from mapped file!!');
+});

e2e/resolve-async/package.json

@@ -0,0 +1,8 @@
+{
+  "type": "module",
+  "jest": {
+    "resolver": "<rootDir>/resolver.cjs",
+    "transform": {
+    }
+  }
+}

e2e/resolve-async/resolver.cjs

@@ -0,0 +1,24 @@
+/**
+ * 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';
+
+const {promisify} = require('util');
+
+const wait = promisify(setTimeout);
+
+module.exports = {
+  async: async (request, opts) => {
+    await wait(500);
+
+    if (request === '../some-file') {
+      request = '../some-other-file';
+    }
+
+    return opts.defaultResolver(request, opts);
+  },
+};

e2e/resolve-async/some-other-file.js

@@ -0,0 +1,8 @@
+/**
+ * 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.
+ */
+
+export default 'Hello from mapped file!!';

e2e/resolve-get-paths/__tests__/resolveGetPaths.test.js

@@ -4,7 +4,6 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-'use strict';
 
 import {resolve} from 'path';
 

e2e/resolve-with-paths/__tests__/resolveWithPaths.test.js

@@ -4,7 +4,6 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-'use strict';
 
 import {resolve} from 'path';
 

packages/jest-resolve/src/__mocks__/package.json

@@ -1,6 +1,5 @@
 {
   "name": "__mocks__",
   "version": "1.0.0",
-  "dependencies": {
-  }
+  "dependencies": {}
 }

packages/jest-resolve/src/__mocks__/userResolver.d.ts

@@ -5,12 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import defaultResolver from '../defaultResolver';
+import type {Resolver} from '../defaultResolver';
 
-// todo: can be replaced with jest.MockedFunction
-declare const userResolver: jest.MockInstance<
-  ReturnType<typeof defaultResolver>,
-  Parameters<typeof defaultResolver>
->;
+declare const userResolver: Resolver;
 
 export default userResolver;

packages/jest-resolve/src/__mocks__/userResolverAsync.d.ts

@@ -0,0 +1,13 @@
+/**
+ * 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.
+ */
+
+import type {Resolver} from '../defaultResolver';
+
+// todo: can be replaced with jest.MockedFunction
+declare const userResolver: Resolver;
+
+export default userResolver;

packages/jest-resolve/src/__mocks__/userResolverAsync.js

@@ -0,0 +1,14 @@
+/**
+ * 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';
+
+module.exports = {
+  async: function userResolver(path, options) {
+    return Promise.resolve('module');
+  },
+};