Run tests in a native Node.js ESM environment

.eslintrc.cjs

@@ -4,10 +4,22 @@ const path = require("path");
 
 const cjsGlobals = ["__dirname", "__filename", "require", "module", "exports"];
 
+const testFiles = [
+  "packages/*/test/**/*.js",
+  "codemods/*/test/**/*.js",
+  "eslint/*/test/**/*.js",
+];
+const sourceFiles = exts => [
+  `packages/*/src/**/*.{${exts}}`,
+  `codemods/*/src/**/*.{${exts}}`,
+  `eslint/*/src/**/*.{${exts}}`,
+];
+
 module.exports = {
   root: true,
   plugins: [
     "import",
+    "node",
     "jest",
     "prettier",
     "@babel/development",
@@ -36,11 +48,7 @@ module.exports = {
       },
     },
     {
-      files: [
-        "packages/*/src/**/*.{js,ts,cjs}",
-        "codemods/*/src/**/*.{js,ts,cjs}",
-        "eslint/*/src/**/*.{js,ts,cjs}",
-      ],
+      files: sourceFiles("js,ts,cjs,mjs"),
       rules: {
         "@babel/development/no-undefined-identifier": "error",
         "@babel/development/no-deprecated-clone": "error",
@@ -51,9 +59,7 @@ module.exports = {
     },
     {
       files: [
-        "packages/*/test/**/*.js",
-        "codemods/*/test/**/*.js",
-        "eslint/*/test/**/*.js",
+        ...testFiles,
         "packages/babel-helper-transform-fixture-test-runner/src/helpers.{ts,js}",
         "test/**/*.js",
       ],
@@ -68,20 +74,21 @@ module.exports = {
         "jest/no-test-callback": "off",
         "jest/valid-describe": "off",
         "import/extensions": ["error", "always"],
+        "import/no-extraneous-dependencies": "off",
         "no-restricted-imports": ["error", { patterns: ["**/src/**"] }],
       },
     },
     {
-      files: [
-        "packages/*/src/**/*.{js,ts}",
-        "codemods/*/src/**/*.{js,ts}",
-        "eslint/*/src/**/*.{js,ts}",
-        "packages/*/test/**/*.js",
-        "codemods/*/test/**/*.js",
-        "eslint/*/test/**/*.js",
-        "packages/babel-helper-transform-fixture-test-runner/src/helpers.{ts,js}",
-        "test/**/*.js",
-      ],
+      files: testFiles,
+      rules: {
+        "node/no-unsupported-features": [
+          "error",
+          { version: "12.17.0", ignores: ["modules"] },
+        ],
+      },
+    },
+    {
+      files: [...sourceFiles("js,ts,mjs"), ...testFiles, "test/**/*.js"],
       excludedFiles: [
         // @babel/register is the require() hook, so it will always be CJS-based
         "packages/babel-register/**/*.{js,ts}",

.gitignore

@@ -52,7 +52,8 @@ package-lock.json
 /packages/babel-runtime-corejs3/core-js/**/*.js
 /packages/babel-runtime-corejs3/core-js-stable/**/*.js
 
-/packages/babel-register/test/.babel
+/packages/babel-register/test/.cache.babel
+/packages/babel-register/test/.index.babel
 /packages/babel-cli/test/tmp
 /packages/babel-node/test/tmp
 /packages/*/lib

codemods/babel-plugin-codemod-object-assign-to-object-spread/test/package.json

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

codemods/babel-plugin-codemod-optional-catch-binding/test/package.json

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

eslint/babel-eslint-parser/test/package.json

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

eslint/babel-eslint-plugin-development-internal/test/rules/package.json

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

eslint/babel-eslint-plugin-development/test/rules/package.json

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

eslint/babel-eslint-plugin/test/rules/package.json

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

eslint/babel-eslint-tests/test/fixtures/package.json

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

eslint/babel-eslint-tests/test/helpers/verifyAndAssertMessages.js

@@ -31,7 +31,7 @@ export default function verifyAndAssertMessages(
           "../../../babel-eslint-shared-fixtures/config/babel.config.js",
         ),
       },
-      ...overrideConfig?.parserOptions,
+      ...(overrideConfig && overrideConfig.parserOptions),
     },
   });
 

eslint/babel-eslint-tests/test/package.json

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

jest.config.js

@@ -2,6 +2,8 @@ const supportsESM = parseInt(process.versions.node) >= 12;
 const isPublishBundle = process.env.IS_PUBLISH;
 
 module.exports = {
+  runner: supportsESM ? "./test/jest-light-runner" : "jest-runner",
+
   collectCoverageFrom: [
     "packages/*/src/**/*.{js,mjs,ts}",
     "codemods/*/src/**/*.{js,mjs,ts}",
@@ -47,7 +49,6 @@ module.exports = {
     "/test/__data__/",
     "<rootDir>/build/",
   ],
-  resolver: supportsESM ? "./test/jestExportsMapResolver.cjs" : null,
   // We don't need module name mappers here as depedencies of workspace
   // package should be declared explicitly in the package.json
   // Yarn will generate correct file links so that Jest can resolve correctly

package.json

@@ -53,6 +53,7 @@
     "eslint-plugin-flowtype": "^8.0.3",
     "eslint-plugin-import": "^2.25.2",
     "eslint-plugin-jest": "^25.2.2",
+    "eslint-plugin-node": "^11.1.0",
     "eslint-plugin-prettier": "^3.4.0",
     "fancy-log": "^1.3.3",
     "flow-bin": "^0.123.0",
@@ -61,8 +62,8 @@
     "gulp-filter": "^7.0.0",
     "gulp-plumber": "^1.2.1",
     "husky": "^7.0.4",
-    "jest": "^27.2.0",
-    "jest-worker": "^27.2.0",
+    "jest": "^27.4.0",
+    "jest-worker": "^27.4.0",
     "lint-staged": "^9.2.0",
     "lodash": "^4.17.21",
     "mergeiterator": "^1.2.5",
@@ -80,6 +81,7 @@
     "eslint/*",
     "packages/*",
     "test/esm",
+    "test/jest-light-runner",
     "test/runtime-integration/*",
     "benchmark"
   ],

packages/babel-cli/test/fixtures/babel/env - SHOW_CONFIG_FOR with ignored file/options.json

@@ -1,6 +1,7 @@
 {
   "args": ["./src/index.js"],
   "env": {
+    "BABEL_ENV": "test",
     "BABEL_SHOW_CONFIG_FOR": "./src/index.js"
   },
   "os": ["darwin", "linux"]

packages/babel-cli/test/fixtures/babel/env - SHOW_CONFIG_FOR with only file/options.json

@@ -1,6 +1,7 @@
 {
   "args": ["./src/index.js"],
   "env": {
+    "BABEL_ENV": "test",
     "BABEL_SHOW_CONFIG_FOR": "./src/index.js"
   },
   "os": ["darwin", "linux"]

packages/babel-cli/test/fixtures/babel/env - SHOW_CONFIG_FOR/in-files/package.json

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

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

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

packages/babel-cli/test/index.js

@@ -45,13 +45,13 @@ const readDir = function (loc, filter) {
 
 const saveInFiles = function (files) {
   // Place an empty .babelrc in each test so tests won't unexpectedly get to repo-level config.
-  if (!fs.existsSync(".babelrc")) {
-    outputFileSync(".babelrc", "{}");
+  if (!fs.existsSync(path.join(tmpLoc, ".babelrc"))) {
+    outputFileSync(path.join(tmpLoc, ".babelrc"), "{}");
   }
 
   Object.keys(files).forEach(function (filename) {
     const content = files[filename];
-    outputFileSync(filename, content);
+    outputFileSync(path.join(tmpLoc, filename), content);
   });
 };
 
@@ -123,7 +123,7 @@ const assertTest = function (stdout, stderr, opts, cwd) {
           const expected = opts.outFiles[filename];
           const actual = actualFiles[filename];
 
-          expect(actual).toBe(expected ?? "");
+          expect(actual).toBe(expected || "");
         }
       } catch (e) {
         e.message += "\n at " + filename;
@@ -152,7 +152,7 @@ const buildTest = function (binName, testName, opts) {
     args = args.concat(opts.args);
     const env = { ...process.env, ...opts.env };
 
-    const spawn = child.spawn(process.execPath, args, { env });
+    const spawn = child.spawn(process.execPath, args, { env, cwd: tmpLoc });
 
     let stderr = "";
     let stdout = "";
@@ -190,28 +190,18 @@ const buildTest = function (binName, testName, opts) {
 };
 
 fs.readdirSync(fixtureLoc).forEach(function (binName) {
-  if (binName.startsWith(".")) return;
+  if (binName.startsWith(".") || binName === "package.json") return;
 
   const suiteLoc = path.join(fixtureLoc, binName);
   describe("bin/" + binName, function () {
-    let cwd;
-
     beforeEach(() => {
-      cwd = process.cwd();
-
       if (fs.existsSync(tmpLoc)) {
         for (const child of fs.readdirSync(tmpLoc)) {
           rimraf.sync(path.join(tmpLoc, child));
         }
       } else {
         fs.mkdirSync(tmpLoc);
       }
-
-      process.chdir(tmpLoc);
-    });
-
-    afterEach(() => {
-      process.chdir(cwd);
     });
 
     fs.readdirSync(suiteLoc).forEach(function (testName) {

packages/babel-cli/test/package.json

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

packages/babel-code-frame/test/package.json

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

packages/babel-core/test/api.js

@@ -138,13 +138,13 @@ describe("parser and generator options", function () {
 describe("api", function () {
   it("exposes the resolvePlugin method", function () {
     expect(() => babel.resolvePlugin("nonexistent-plugin")).toThrow(
-      /Cannot resolve module 'babel-plugin-nonexistent-plugin'/,
+      /Cannot (?:find|resolve) module 'babel-plugin-nonexistent-plugin'/,
     );
   });
 
   it("exposes the resolvePreset method", function () {
     expect(() => babel.resolvePreset("nonexistent-preset")).toThrow(
-      /Cannot resolve module 'babel-preset-nonexistent-preset'/,
+      /Cannot (?:find|resolve) module 'babel-preset-nonexistent-preset'/,
     );
   });
 

packages/babel-core/test/config-chain.js

@@ -14,7 +14,7 @@ import { isMJS, loadOptionsAsync, skipUnsupportedESM } from "./helpers/esm.js";
 // TODO: In Babel 8, we can directly uses fs.promises which is supported by
 // node 8+
 const pfs =
-  fs.promises ??
+  fs.promises ||
   new Proxy(fs, {
     get(target, name) {
       if (name === "copyFile") {

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

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

packages/babel-core/test/package.json

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

packages/babel-core/test/resolution.js

@@ -355,8 +355,8 @@ describe("addon resolution", function () {
       // `require.resolve` is provided.
       // see https://github.com/babel/babel/pull/12439/files#r535996000
       process.versions.node.startsWith("8.")
-        ? /Cannot resolve module 'babel-preset-foo'/
-        : /Cannot resolve module 'babel-preset-foo'.*\n- If you want to resolve "foo", use "module:foo"/,
+        ? /Cannot (?:find|resolve) module 'babel-preset-foo'/
+        : /Cannot (?:find|resolve) module 'babel-preset-foo'.*\n- If you want to resolve "foo", use "module:foo"/s,
     );
   });
 
@@ -371,8 +371,8 @@ describe("addon resolution", function () {
       });
     }).toThrow(
       process.versions.node.startsWith("8.")
-        ? /Cannot resolve module 'babel-plugin-foo'/
-        : /Cannot resolve module 'babel-plugin-foo'.*\n- If you want to resolve "foo", use "module:foo"/,
+        ? /Cannot (?:find|resolve) module 'babel-plugin-foo'/
+        : /Cannot (?:find|resolve) module 'babel-plugin-foo'.*\n- If you want to resolve "foo", use "module:foo"/s,
     );
   });
 
@@ -387,8 +387,8 @@ describe("addon resolution", function () {
       });
     }).toThrow(
       process.versions.node.startsWith("8.")
-        ? /Cannot resolve module 'babel-preset-foo'/
-        : /Cannot resolve module 'babel-preset-foo'.*\n- Did you mean "@babel\/foo"\?/,
+        ? /Cannot (?:find|resolve) module 'babel-preset-foo'/
+        : /Cannot (?:find|resolve) module 'babel-preset-foo'.*\n- Did you mean "@babel\/foo"\?/s,
     );
   });
 
@@ -403,8 +403,8 @@ describe("addon resolution", function () {
       });
     }).toThrow(
       process.versions.node.startsWith("8.")
-        ? /Cannot resolve module 'babel-plugin-foo'/
-        : /Cannot resolve module 'babel-plugin-foo'.*\n- Did you mean "@babel\/foo"\?/,
+        ? /Cannot (?:find|resolve) module 'babel-plugin-foo'/
+        : /Cannot (?:find|resolve) module 'babel-plugin-foo'.*\n- Did you mean "@babel\/foo"\?/s,
     );
   });
 
@@ -419,8 +419,8 @@ describe("addon resolution", function () {
       });
     }).toThrow(
       process.versions.node.startsWith("8.")
-        ? /Cannot resolve module 'babel-preset-testplugin'/
-        : /Cannot resolve module 'babel-preset-testplugin'.*\n- Did you accidentally pass a plugin as a preset\?/,
+        ? /Cannot (?:find|resolve) module 'babel-preset-testplugin'/
+        : /Cannot (?:find|resolve) module 'babel-preset-testplugin'.*\n- Did you accidentally pass a plugin as a preset\?/s,
     );
   });
 
@@ -435,8 +435,8 @@ describe("addon resolution", function () {
       });
     }).toThrow(
       process.versions.node.startsWith("8.")
-        ? /Cannot resolve module 'babel-plugin-testpreset'/
-        : /Cannot resolve module 'babel-plugin-testpreset'.*\n- Did you accidentally pass a preset as a plugin\?/,
+        ? /Cannot (?:find|resolve) module 'babel-plugin-testpreset'/
+        : /Cannot (?:find|resolve) module 'babel-plugin-testpreset'.*\n- Did you accidentally pass a preset as a plugin\?/s,
     );
   });
 
@@ -449,7 +449,7 @@ describe("addon resolution", function () {
         babelrc: false,
         presets: ["foo"],
       });
-    }).toThrow(/Cannot resolve module 'babel-preset-foo'/);
+    }).toThrow(/Cannot (?:find|resolve) module 'babel-preset-foo'/);
   });
 
   it("should throw about missing plugins", function () {
@@ -461,6 +461,6 @@ describe("addon resolution", function () {
         babelrc: false,
         plugins: ["foo"],
       });
-    }).toThrow(/Cannot resolve module 'babel-plugin-foo'/);
+    }).toThrow(/Cannot (?:find|resolve) module 'babel-plugin-foo'/);
   });
 });

packages/babel-generator/test/package.json

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

packages/babel-helper-annotate-as-pure/test/package.json

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

packages/babel-helper-compilation-targets/test/load-browserslist-package-json/package.json

@@ -1,3 +1,4 @@
 {
-  "browserslist": "chrome 4"
+  "browserslist": "chrome 4",
+  "type": "module"
 }

packages/babel-helper-compilation-targets/test/package.json

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

packages/babel-helper-create-class-features-plugin/test/package.json

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

packages/babel-helper-create-regexp-features-plugin/test/package.json

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

packages/babel-helper-fixtures/src/index.ts

@@ -60,7 +60,11 @@ function shouldIgnore(name, ignore?: Array<string>) {
   const base = path.basename(name, ext);
 
   return (
-    name[0] === "." || ext === ".md" || base === "LICENSE" || base === "options"
+    name[0] === "." ||
+    ext === ".md" ||
+    base === "LICENSE" ||
+    base === "options" ||
+    name === "package.json"
   );
 }
 

packages/babel-helper-module-imports/test/package.json

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

packages/babel-helper-optimise-call-expression/test/package.json

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