From 14df1ff9b2130e4aabe92dba2da9ae817e25e753 Mon Sep 17 00:00:00 2001
From: Simen Bekkhus <sbekkhus91@gmail.com>
Date: Sun, 11 Aug 2019 13:29:43 +0200
Subject: [PATCH 1/2] feat: add sync way of requiring and transpiling module

---
 .../jest-transform/src/ScriptTransformer.ts   | 37 ++++++++++++++++---
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/packages/jest-transform/src/ScriptTransformer.ts b/packages/jest-transform/src/ScriptTransformer.ts
index aafff4c113fe..7d3137a04d49 100644
--- a/packages/jest-transform/src/ScriptTransformer.ts
+++ b/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
@@ -435,10 +435,18 @@ 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 +475,28 @@ 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 cbResult.then(
+          () => {
+            revertHook();
+
+            return module;
+          },
+          error => {
+            revertHook();
+
+            return Promise.reject(error);
+          },
+        );
       }
     } finally {
       revertHook();

From 192893e9b416a382b7de95eaad8a068afc25ba95 Mon Sep 17 00:00:00 2001
From: Simen Bekkhus <sbekkhus91@gmail.com>
Date: Sun, 11 Aug 2019 18:48:15 +0200
Subject: [PATCH 2/2] await-finally helper

---
 .../jest-transform/src/ScriptTransformer.ts   | 24 ++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/packages/jest-transform/src/ScriptTransformer.ts b/packages/jest-transform/src/ScriptTransformer.ts
index 7d3137a04d49..1f7506b7af0e 100644
--- a/packages/jest-transform/src/ScriptTransformer.ts
+++ b/packages/jest-transform/src/ScriptTransformer.ts
@@ -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;
@@ -485,17 +496,8 @@ export default class ScriptTransformer {
       const cbResult = callback(module);
 
       if (isPromise(cbResult)) {
-        return cbResult.then(
-          () => {
-            revertHook();
-
-            return module;
-          },
-          error => {
-            revertHook();
-
-            return Promise.reject(error);
-          },
+        return waitForPromiseWithCleanup(cbResult, revertHook).then(
+          () => module,
         );
       }
     } finally {