fix: call exported config function

CHANGELOG.md

@@ -11,6 +11,7 @@
 - `[jest-circus]` Add missing `slash` dependency ([#11465](https://github.com/facebook/jest/pull/11465))
 - `[jest-circus, @jest/test-sequencer]` Remove dependency on `jest-runner` ([#11466](https://github.com/facebook/jest/pull/11466))
 - `[jest-config]` Resolve `config.runner` to absolute path ([#11465](https://github.com/facebook/jest/pull/11465))
+- `[jest-config]` Make sure to support functions as config ([#11475](https://github.com/facebook/jest/pull/11475))
 - `[jest-core]` Do not warn about `DNSCHANNEL` handles when using the `--detectOpenHandles` option ([#11470](https://github.com/facebook/jest/pull/11470))
 - `[jest-runner]` Remove dependency on `jest-config` ([#11466](https://github.com/facebook/jest/pull/11466))
 - `[jest-worker]` Loosen engine requirement to `>= 10.13.0` ([#11451](https://github.com/facebook/jest/pull/11451))

packages/jest-config/src/__tests__/readConfigs.test.ts

@@ -4,48 +4,19 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-import {Config} from '@jest/types';
 import {readConfigs} from '../index';
 
-let mockResult;
 jest.mock('graceful-fs', () => ({
   ...jest.requireActual('fs'),
   existsSync: jest.fn(() => true),
   lstatSync: jest.fn(() => ({
     isDirectory: () => false,
   })),
 }));
-jest.mock('../readConfigFileAndSetRootDir', () => jest.fn(() => mockResult));
 
 test('readConfigs() throws when called without project paths', async () => {
   await expect(
     // @ts-expect-error
     readConfigs(null /* argv */, [] /* projectPaths */),
   ).rejects.toThrowError('jest: No configuration found for any project.');
 });
-
-test('readConfigs() loads async config file', async () => {
-  mockResult = jest.fn(async () => ({
-    rootDir: './',
-  }));
-  await expect(
-    readConfigs(
-      <Config.Argv>{} /* argv */,
-      ['./some-jest-config-file.js'] /* projectPaths */,
-    ),
-  ).resolves.toHaveProperty('configs');
-  expect(mockResult).toHaveBeenCalled();
-});
-
-test('readConfigs() reject if async was rejected', async () => {
-  mockResult = jest.fn(async () => {
-    throw new Error('Some error');
-  });
-  await expect(
-    readConfigs(
-      <Config.Argv>{} /* argv */,
-      ['./some-jest-config-file.js'] /* projectPaths */,
-    ),
-  ).rejects.toBeTruthy();
-  expect(mockResult).toHaveBeenCalled();
-});

packages/jest-config/src/index.ts

@@ -45,9 +45,7 @@ export async function readConfig(
   parentConfigDirname?: Config.Path | null,
   projectIndex: number = Infinity,
 ): Promise<ReadConfig> {
-  let rawOptions:
-    | Config.InitialOptions
-    | (() => Config.InitialOptions | Promise<Config.InitialOptions>);
+  let rawOptions: Config.InitialOptions;
   let configPath = null;
 
   if (typeof packageRootOrConfig !== 'string') {
@@ -87,10 +85,6 @@ export async function readConfig(
     rawOptions = await readConfigFileAndSetRootDir(configPath);
   }
 
-  if (typeof rawOptions === 'function') {
-    rawOptions = await rawOptions();
-  }
-
   const {options, hasDeprecationWarnings} = await normalize(
     rawOptions,
     argv,

packages/jest-config/src/readConfigFileAndSetRootDir.ts

@@ -58,6 +58,10 @@ export default async function readConfigFileAndSetRootDir(
     configObject = configObject.jest || {};
   }
 
+  if (typeof configObject === 'function') {
+    configObject = await configObject();
+  }
+
   if (configObject.rootDir) {
     // We don't touch it if it has an absolute path specified
     if (!path.isAbsolute(configObject.rootDir)) {