feat: add sync way of requiring and transpiling module (#8808)

Author: SimenB

packages/jest-transform/src/ScriptTransformer.ts

@@ -9,7 +9,7 @@ import crypto from 'crypto';
 import path from 'path';
 import vm from 'vm';
 import {Config} from '@jest/types';
-import {createDirectory} from 'jest-util';
+import {createDirectory, isPromise} from 'jest-util';
 import fs from 'graceful-fs';
 import {transformSync as babelTransform} from '@babel/core';
 // @ts-ignore: should just be `require.resolve`, but the tests mess that up
@@ -51,6 +51,17 @@ const projectCaches: WeakMap<
 // To reset the cache for specific changesets (rather than package version).
 const CACHE_VERSION = '1';
 
+async function waitForPromiseWithCleanup(
+ promise: Promise<any>,
+ cleanup: () => void,
+) {
+ try {
+ await promise;
+ } finally {
+ cleanup();
+ }
+}
+
 export default class ScriptTransformer {
  static EVAL_RESULT_VARIABLE: 'Object.<anonymous>';
  private _cache: ProjectCache;
@@ -435,10 +446,18 @@ export default class ScriptTransformer {
  return fileSource;
  }
 
- async requireAndTranspileModule<ModuleType = unknown>(
+ requireAndTranspileModule<ModuleType = unknown>(
+ moduleName: string,
+ callback?: (module: ModuleType) => void,
+ ): ModuleType;
+ requireAndTranspileModule<ModuleType = unknown>(
+ moduleName: string,
+ callback?: (module: ModuleType) => Promise<void>,
+ ): Promise<ModuleType>;
+ requireAndTranspileModule<ModuleType = unknown>(
  moduleName: string,
  callback?: (module: ModuleType) => void | Promise<void>,
- ): Promise<ModuleType> {
+ ): ModuleType | Promise<ModuleType> {
  // Load the transformer to avoid a cycle where we need to load a
  // transformer in order to transform it in the require hooks
  this.preloadTransformer(moduleName);
@@ -467,9 +486,19 @@ export default class ScriptTransformer {
  );
  const module: ModuleType = require(moduleName);
 
+ if (!callback) {
+ revertHook();
+
+ return module;
+ }
+
  try {
- if (callback) {
- await callback(module);
+ const cbResult = callback(module);
+
+ if (isPromise(cbResult)) {
+ return waitForPromiseWithCleanup(cbResult, revertHook).then(
+ () => module,
+ );
  }
  } finally {
  revertHook();