Fix @babel/register test mocks

packages/babel-register/src/nodeWrapper.ts

@@ -13,6 +13,9 @@ const internalModuleCache = Object.create(null);
 
 Module._cache = internalModuleCache;
 const node = require("./node");
+
+// NOTE: This Module._cache set is intercepted by the beforeEach hook in
+// packages/babel-register/test/index.js to install dependencies mocks.
 Module._cache = globalModuleCache;
 
 // Add source-map-support to global cache as it's stateful

packages/babel-register/test/cache.js

@@ -1,13 +1,13 @@
 import fs from "fs";
 import path from "path";
 import { fileURLToPath } from "url";
-import { createRequire } from "module";
+import { createRequire, Module } from "module";
 
 const require = createRequire(import.meta.url);
 
 const testCacheFilename = path.join(
   path.dirname(fileURLToPath(import.meta.url)),
-  ".babel",
+  ".cache.babel",
 );
 const oldBabelDisableCacheValue = process.env.BABEL_DISABLE_CACHE;
 
@@ -35,14 +35,30 @@ function resetCache() {
   process.env.BABEL_DISABLE_CACHE = oldBabelDisableCacheValue;
 }
 
+const OLD_JEST_MOCKS = !!jest.doMock;
+
 describe("@babel/register - caching", () => {
   describe("cache", () => {
     let load, get, setDirty, save;
     let consoleWarnSpy;
 
+    if (!OLD_JEST_MOCKS) {
+      let oldModuleCache;
+      beforeAll(() => {
+        oldModuleCache = Module._cache;
+      });
+      afterAll(() => {
+        Module._cache = oldModuleCache;
+      });
+    }
+
     beforeEach(() => {
       // Since lib/cache is a singleton we need to fully reload it
-      jest.resetModules(require);
+      if (OLD_JEST_MOCKS) {
+        jest.resetModules();
+      } else {
+        Module._cache = {};
+      }
       const cache = require("../lib/cache.js");
 
       load = cache.load;

packages/babel-register/test/fixtures/package.json

@@ -0,0 +1 @@
+{ "type": "commonjs" }

packages/babel-register/test/index.js

@@ -1,47 +1,19 @@
-import { createRequire } from "module";
+import { createRequire, Module } from "module";
 import path from "path";
 import fs from "fs";
 import child from "child_process";
+import { fileURLToPath } from "url";
 
+const dirname = path.dirname(fileURLToPath(import.meta.url));
 const require = createRequire(import.meta.url);
 
-let currentHook;
-let currentOptions;
-let sourceMapSupport = false;
-
 const registerFile = require.resolve("../lib/index");
-const testCacheFilename = path.join(__dirname, ".babel");
+const testCacheFilename = path.join(dirname, ".index.babel");
 const testFile = require.resolve("./fixtures/babelrc/es2015");
 const testFileContent = fs.readFileSync(testFile);
-const sourceMapTestFile = require.resolve("./fixtures/source-map/index");
-const sourceMapNestedTestFile = require.resolve(
-  "./fixtures/source-map/foo/bar",
-);
-const internalModulesTestFile = require.resolve(
-  "./fixtures/internal-modules/index",
-);
-
-jest.mock("pirates", () => {
-  return {
-    addHook(hook, opts) {
-      currentHook = hook;
-      currentOptions = opts;
-
-      return () => {
-        currentHook = null;
-        currentOptions = null;
-      };
-    },
-  };
-});
 
-jest.mock("source-map-support", () => {
-  return {
-    install() {
-      sourceMapSupport = true;
-    },
-  };
-});
+const piratesPath = require.resolve("pirates");
+const smsPath = require.resolve("source-map-support");
 
 const defaultOptions = {
   exts: [".js", ".jsx", ".es6", ".es", ".mjs", ".cjs"],
@@ -60,7 +32,31 @@ function resetCache() {
   process.env.BABEL_CACHE_PATH = null;
 }
 
+const OLD_JEST_MOCKS = !!jest.doMock;
+
 describe("@babel/register", function () {
+  let currentHook, currentOptions, sourceMapSupport;
+
+  const mocks = {
+    ["pirates"]: {
+      addHook(hook, opts) {
+        currentHook = hook;
+        currentOptions = opts;
+
+        return () => {
+          currentHook = null;
+          currentOptions = null;
+        };
+      },
+    },
+
+    ["source-map-support"]: {
+      install() {
+        sourceMapSupport = true;
+      },
+    },
+  };
+
   let babelRegister;
 
   function setupRegister(config = { babelrc: false }) {
@@ -83,6 +79,12 @@ describe("@babel/register", function () {
     cleanCache();
   }
 
+  beforeEach(() => {
+    currentHook = null;
+    currentOptions = null;
+    sourceMapSupport = false;
+  });
+
   afterEach(async () => {
     // @babel/register saves the cache on process.nextTick.
     // We need to wait for at least one tick so that when jest
@@ -91,16 +93,60 @@ describe("@babel/register", function () {
     await new Promise(setImmediate);
 
     revertRegister();
-    currentHook = null;
-    currentOptions = null;
-    sourceMapSupport = false;
-    jest.resetModules();
   });
 
   afterAll(() => {
     resetCache();
   });
 
+  if (OLD_JEST_MOCKS) {
+    jest.doMock("pirates", () => mocks["pirates"]);
+    jest.doMock("source-map-support", () => mocks["source-map-support"]);
+
+    afterEach(() => {
+      jest.resetModules();
+    });
+  } else {
+    let originalRequireCacheDescriptor;
+    beforeAll(() => {
+      originalRequireCacheDescriptor = Object.getOwnPropertyDescriptor(
+        Module,
+        "_cache",
+      );
+    });
+
+    beforeEach(() => {
+      const isEmptyObj = obj =>
+        Object.getPrototypeOf(obj) === null && Object.keys(obj).length === 0;
+
+      // This setter intercepts the Module._cache assignment in
+      // packages/babel-register/src/nodeWrapper.js to install in the
+      // internal isolated cache.
+      const emptyInitialCache = {};
+      Object.defineProperty(Module, "_cache", {
+        get: () => emptyInitialCache,
+        set(value) {
+          expect(isEmptyObj(value)).toBe(true);
+
+          Object.defineProperty(Module, "_cache", {
+            value,
+            enumerable: originalRequireCacheDescriptor.enumerable,
+            configurable: originalRequireCacheDescriptor.configurable,
+            writable: originalRequireCacheDescriptor.writable,
+          });
+          value[piratesPath] = { exports: mocks["pirates"] };
+          value[smsPath] = { exports: mocks["source-map-support"] };
+        },
+        enumerable: originalRequireCacheDescriptor.enumerable,
+        configurable: originalRequireCacheDescriptor.configurable,
+      });
+    });
+
+    afterAll(() => {
+      Object.defineProperty(Module, "_cache", originalRequireCacheDescriptor);
+    });
+  }
+
   test("registers hook correctly", () => {
     setupRegister();
 
@@ -160,11 +206,11 @@ describe("@babel/register", function () {
     const output = await spawnNodeAsync([
       "-r",
       registerFile,
-      sourceMapTestFile,
+      require.resolve("./fixtures/source-map/index"),
     ]);
     const sourceMap = JSON.parse(output);
     expect(sourceMap.map.sourceRoot + sourceMap.map.sources[0]).toBe(
-      sourceMapNestedTestFile,
+      require.resolve("./fixtures/source-map/foo/bar"),
     );
   });
 
@@ -195,14 +241,16 @@ describe("@babel/register", function () {
     // Need a clean environment without `convert-source-map`
     // already in the require cache, so we spawn a separate process
 
-    const output = await spawnNodeAsync([internalModulesTestFile]);
+    const output = await spawnNodeAsync([
+      require.resolve("./fixtures/internal-modules/index.js"),
+    ]);
     const { convertSourceMap } = JSON.parse(output);
     expect(convertSourceMap).toMatch("/* transformed */");
   });
 });
 
 function spawnNodeAsync(args) {
-  const spawn = child.spawn(process.execPath, args, { cwd: __dirname });
+  const spawn = child.spawn(process.execPath, args, { cwd: dirname });
 
   let output = "";
   let callback;

test/jest-light-runner/src/global-setup.js

@@ -24,7 +24,4 @@ globalThis.afterEach = circus.afterEach;
 globalThis.jest = {
   fn: mock.fn,
   spyOn: mock.spyOn,
-  resetModules: require => {
-    for (const k of Object.keys(require.cache)) delete require.cache[k];
-  },
 };