Enforce _foo.default || _foo to import lib files in tests (#14673)

.eslintrc.cjs

@@ -83,6 +83,7 @@ module.exports = {
           "error",
           { version: "12.17.0", ignores: ["modules"] },
         ],
+        "@babel/development-internal/require-default-import-fallback": "error",
       },
     },
     {

eslint/babel-eslint-plugin-development-internal/src/index.cjs

@@ -1,7 +1,6 @@
-const reportErrorMessageFormat = require("./rules/report-error-message-format.cjs");
-
 const rules = {
-  "report-error-message-format": reportErrorMessageFormat,
+  "report-error-message-format": require("./rules/report-error-message-format.cjs"),
+  "require-default-import-fallback": require("./rules/require-default-import-fallback.cjs"),
 };
 
 exports.rules = rules;

eslint/babel-eslint-plugin-development-internal/src/rules/require-default-import-fallback.cjs

@@ -0,0 +1,76 @@
+module.exports = {
+  meta: {
+    type: "suggestion",
+    docs: {
+      description: "",
+    },
+    fixable: "code",
+  },
+  create(ctx) {
+    return {
+      ImportDeclaration(node) {
+        const filename = ctx.getFilename();
+        const src = node.source.value;
+        if (
+          // Not a source file in the monorepo
+          (!src.includes("/lib/") && !src.startsWith("@babel/")) ||
+          // This package already always uses the ESM entrypoint.
+          src === "@babel/helper-plugin-test-runner" ||
+          // Unclear if we'll convert this or it will stay as JSON.
+          src.startsWith("@babel/compat-data") ||
+          // This will not become an ESM file.
+          src.endsWith(".cjs") ||
+          // @babel/core automatically unwraps .default from plugins/presets.
+          /^@babel\/(plugin|preset)-/.test(src) ||
+          (src.endsWith("./lib/index.js") &&
+            /babel-(plugin|preset)-/.test(filename))
+        ) {
+          return;
+        }
+
+        const defaultSpecifier = node.specifiers.find(
+          spec => spec.type === "ImportDefaultSpecifier",
+        );
+        if (!defaultSpecifier) return;
+
+        const scope = ctx.getScope();
+
+        const { name: local } = defaultSpecifier.local;
+        const { references } = scope.variables.find(v => v.name === local);
+
+        const isRef = node => node.type === "Identifier" && node.name === local;
+        const isRefDefault = node =>
+          node.type === "MemberExpression" &&
+          !node.computed &&
+          node.property.name === "default" &&
+          isRef(node.object);
+
+        for (const { identifier } of references) {
+          const base =
+            identifier.parent.type === "MemberExpression"
+              ? identifier.parent.parent
+              : identifier.parent;
+
+          if (
+            base.type !== "LogicalExpression" ||
+            base.operator !== "||" ||
+            !isRefDefault(base.left) ||
+            !isRef(base.right)
+          ) {
+            const expected = `${local}.default || ${local}`;
+            ctx.report({
+              node: identifier,
+              message: `Default imports of source files must be used with an explicit fallback: \`${expected}\``,
+              fix(fixer) {
+                const base = isRefDefault(identifier.parent)
+                  ? identifier.parent
+                  : identifier;
+                return fixer.replaceText(base, `(${expected})`);
+              },
+            });
+          }
+        }
+      },
+    };
+  },
+};

packages/babel-code-frame/test/index.js

@@ -2,7 +2,7 @@ import chalk from "chalk";
 import stripAnsi from "strip-ansi";
 
 import _codeFrame, { codeFrameColumns } from "../lib/index.js";
-const codeFrame = _codeFrame.default;
+const codeFrame = _codeFrame.default || _codeFrame;
 
 describe("@babel/code-frame", function () {
   test("basic usage", function () {

packages/babel-core/package.json

@@ -66,7 +66,10 @@
   },
   "devDependencies": {
     "@babel/helper-transform-fixture-test-runner": "workspace:^",
+    "@babel/plugin-syntax-flow": "workspace:^",
+    "@babel/plugin-transform-flow-strip-types": "workspace:^",
     "@babel/plugin-transform-modules-commonjs": "workspace:^",
+    "@babel/preset-env": "workspace:^",
     "@jridgewell/trace-mapping": "^0.3.8",
     "@types/convert-source-map": "^1.5.1",
     "@types/debug": "^4.1.0",

packages/babel-core/test/api.js

@@ -5,11 +5,11 @@ import generator from "@babel/generator";
 import { fileURLToPath } from "url";
 
 import _Plugin from "../lib/config/plugin.js";
-const Plugin = _Plugin.default;
+const Plugin = _Plugin.default || _Plugin;
 
-import presetEnv from "../../babel-preset-env/lib/index.js";
-import pluginSyntaxFlow from "../../babel-plugin-syntax-flow/lib/index.js";
-import pluginFlowStripTypes from "../../babel-plugin-transform-flow-strip-types/lib/index.js";
+import presetEnv from "@babel/preset-env";
+import pluginSyntaxFlow from "@babel/plugin-syntax-flow";
+import pluginFlowStripTypes from "@babel/plugin-transform-flow-strip-types";
 
 const cwd = path.dirname(fileURLToPath(import.meta.url));
 
@@ -73,7 +73,7 @@ describe("parser and generator options", function () {
       return opts.parser.parse(code);
     },
     print: function (ast) {
-      return generator(ast);
+      return (generator.default || generator)(ast);
     },
   };
 

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

@@ -6,7 +6,7 @@ import * as babel from "../lib/index.js";
 import rimraf from "rimraf";
 
 import _getTargets from "@babel/helper-compilation-targets";
-const getTargets = _getTargets.default;
+const getTargets = _getTargets.default || _getTargets;
 
 const dirname = path.dirname(fileURLToPath(import.meta.url));
 

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

@@ -8,7 +8,7 @@ import { createRequire } from "module";
 
 const require = createRequire(import.meta.url);
 
-const loadConfig = _loadConfigRunner.default.sync;
+const loadConfig = (_loadConfigRunner.default || _loadConfigRunner).sync;
 
 describe("@babel/core config loading", () => {
   const FILEPATH = path.join(

packages/babel-core/test/evaluation.js

@@ -1,7 +1,7 @@
 import { parse } from "@babel/parser";
 
 import _traverse from "@babel/traverse";
-const traverse = _traverse.default;
+const traverse = _traverse.default || _traverse;
 
 describe("evaluation", function () {
   function addTest(code, type, value, notConfident) {

packages/babel-core/test/merge-map.js

@@ -1,5 +1,5 @@
 import _mergeSourceMap from "../lib/transformation/file/merge-map.js";
-const mergeSourceMap = _mergeSourceMap.default;
+const mergeSourceMap = _mergeSourceMap.default || _mergeSourceMap;
 
 describe("merge-map", () => {
   it("returns a plain js object", () => {

packages/babel-core/test/path.js

@@ -3,7 +3,7 @@ import { fileURLToPath } from "url";
 import path from "path";
 
 import _Plugin from "../lib/config/plugin.js";
-const Plugin = _Plugin.default;
+const Plugin = _Plugin.default || _Plugin;
 
 const cwd = path.dirname(fileURLToPath(import.meta.url));
 

packages/babel-core/test/plugins.js

@@ -2,7 +2,7 @@ import runner from "@babel/helper-transform-fixture-test-runner";
 import { fileURLToPath } from "url";
 import path from "path";
 
-runner.default(
+(runner.default || runner)(
   path.join(path.dirname(fileURLToPath(import.meta.url)), "fixtures/plugins"),
   "plugins",
 );

packages/babel-core/test/transformation.js

@@ -2,7 +2,7 @@ import runner from "@babel/helper-transform-fixture-test-runner";
 import { fileURLToPath } from "url";
 import path from "path";
 
-runner.default(
+(runner.default || runner)(
   path.join(
     path.dirname(fileURLToPath(import.meta.url)),
     "/fixtures/transformation",

packages/babel-generator/test/arrow-functions.js

@@ -1,7 +1,7 @@
 import { parse } from "@babel/parser";
 
 import _generate from "../lib/index.js";
-const generate = _generate.default;
+const generate = _generate.default || _generate;
 
 describe("parameter parentheses", () => {
   // Common source text for several snapshot tests

packages/babel-generator/test/index.js

@@ -8,8 +8,8 @@ import { fileURLToPath } from "url";
 
 import _Printer from "../lib/printer.js";
 import _generate, { CodeGenerator } from "../lib/index.js";
-const Printer = _Printer.default;
-const generate = _generate.default;
+const Printer = _Printer.default || _Printer;
+const generate = _generate.default || _generate;
 
 describe("generation", function () {
   it("completeness", function () {
@@ -806,7 +806,7 @@ describe("CodeGenerator", function () {
   });
 });
 
-const suites = fixtures.default(
+const suites = (fixtures.default || fixtures)(
   path.join(path.dirname(fileURLToPath(import.meta.url)), "fixtures"),
 );
 

packages/babel-helper-annotate-as-pure/test/index.js

@@ -1,5 +1,5 @@
 import _annotateAsPure from "../lib/index.js";
-const annotateAsPure = _annotateAsPure.default;
+const annotateAsPure = _annotateAsPure.default || _annotateAsPure;
 
 describe("@babel/helper-annotate-as-pure", () => {
   it("will add leading comment", () => {

packages/babel-helper-check-duplicate-nodes/test/index.js

@@ -1,6 +1,7 @@
 import _checkDuplicateNodes from "../lib/index.js";
 import { parseSync, traverse, types as t } from "@babel/core";
-const checkDuplicateNodes = _checkDuplicateNodes.default;
+const checkDuplicateNodes =
+  _checkDuplicateNodes.default || _checkDuplicateNodes;
 
 describe("checkDuplicateNodes", () => {
   it("should throw on duplicate AST nodes within same parent", () => {

packages/babel-helper-compilation-targets/test/browserslist-extends/browserslist-extends.spec.js

@@ -2,7 +2,7 @@ import { dirname, resolve } from "path";
 import { fileURLToPath } from "url";
 
 import _getTargets from "../../lib/index.js";
-const getTargets = _getTargets.default;
+const getTargets = _getTargets.default || _getTargets;
 
 const currentDir = dirname(fileURLToPath(import.meta.url));
 

packages/babel-helper-compilation-targets/test/custom-browserslist-env/custom-browserslist-env.spec.js

@@ -2,7 +2,7 @@ import { fileURLToPath } from "url";
 import path from "path";
 
 import _getTargets from "../../lib/index.js";
-const getTargets = _getTargets.default;
+const getTargets = _getTargets.default || _getTargets;
 
 it("allows custom browserslist env", () => {
   const actual = getTargets(

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

@@ -2,7 +2,7 @@ import { fileURLToPath } from "url";
 import path from "path";
 
 import _getTargets from "../../lib/index.js";
-const getTargets = _getTargets.default;
+const getTargets = _getTargets.default || _getTargets;
 
 const oldCwd = process.cwd();
 

packages/babel-helper-compilation-targets/test/load-browserslistrc/load-browserslistrc.spec.js

@@ -2,7 +2,7 @@ import { fileURLToPath } from "url";
 import path from "path";
 
 import _getTargets from "../../lib/index.js";
-const getTargets = _getTargets.default;
+const getTargets = _getTargets.default || _getTargets;
 
 const oldCwd = process.cwd();
 

packages/babel-helper-compilation-targets/test/targets-parser.spec.js

@@ -3,7 +3,7 @@ import { join, dirname } from "path";
 import { fileURLToPath } from "url";
 
 import _getTargets from "../lib/index.js";
-const getTargets = _getTargets.default;
+const getTargets = _getTargets.default || _getTargets;
 
 describe("getTargets", () => {
   it("parses", () => {

packages/babel-helper-optimise-call-expression/test/index.js

@@ -3,8 +3,9 @@ import * as t from "@babel/types";
 
 import _generator from "@babel/generator";
 import _optimizeCallExpression from "../lib/index.js";
-const generator = _generator.default;
-const optimizeCallExpression = _optimizeCallExpression.default;
+const generator = _generator.default || _generator;
+const optimizeCallExpression =
+  _optimizeCallExpression.default || _optimizeCallExpression;
 
 function transformInput(input, thisIdentifier) {
   const ast = parse(input);

packages/babel-helper-plugin-test-runner/esm.mjs

@@ -1,11 +1,12 @@
 import _cjs from "./lib/index.js";
+const cjs = _cjs.default || _cjs;
 
-const adapter = _cjs.default.bind();
+const adapter = cjs.bind();
 
 // For backward compatibility with the CJS-only version, this makes
 //    import _x from "@babel/helper-plugin-test-runner"
 //    const x = _x.default
 // still work.
-adapter.default = _cjs.default;
+adapter.default = cjs;
 
 export default adapter;

packages/babel-helper-simple-access/test/index.js

@@ -7,7 +7,7 @@ const plugin = (_api, options) => {
   return {
     visitor: {
       Program(path) {
-        simplifyAccess.default(
+        (simplifyAccess.default || simplifyAccess)(
           path,
           new Set(bindingNames),
           includeUpdateExpression,

packages/babel-highlight/test/index.js

@@ -2,7 +2,7 @@ import chalk from "chalk";
 import stripAnsi from "strip-ansi";
 
 import _highlight, { shouldHighlight, getChalk } from "../lib/index.js";
-const highlight = _highlight.default;
+const highlight = _highlight.default || _highlight;
 
 describe("@babel/highlight", function () {
   function stubColorSupport(supported) {

packages/babel-parser/test/helpers/run-fixture-tests.js

@@ -10,7 +10,8 @@ import toContextualSyntaxError from "./to-contextual-syntax-error.js";
 
 const { CI, OVERWRITE } = process.env;
 const { stringify, parse: JSONParse } = JSON;
-const checkDuplicateNodes = _checkDuplicateNodes.default;
+const checkDuplicateNodes =
+  _checkDuplicateNodes.default || _checkDuplicateNodes;
 
 const writeFileWithNewline = (path, string) =>
   writeFileSync(path, `${string}\n`, "utf-8");

packages/babel-plugin-proposal-object-rest-spread/test/hasMoreThanOneBinding.skip-bundled.js

@@ -2,7 +2,8 @@ import { parse } from "@babel/parser";
 
 import _shouldStoreRHSInTemporaryVariable from "../lib/shouldStoreRHSInTemporaryVariable.js";
 const shouldStoreRHSInTemporaryVariable =
-  _shouldStoreRHSInTemporaryVariable.default;
+  _shouldStoreRHSInTemporaryVariable.default ||
+  _shouldStoreRHSInTemporaryVariable;
 
 function getFistObjectPattern(program) {
   return parse(program, { sourceType: "module" }).program.body[0]

packages/babel-preset-env/test/get-option-specific-excludes.spec.js

@@ -1,5 +1,6 @@
 import _getOptionSpecificExcludesFor from "../lib/get-option-specific-excludes.js";
-const getOptionSpecificExcludesFor = _getOptionSpecificExcludesFor.default;
+const getOptionSpecificExcludesFor =
+  _getOptionSpecificExcludesFor.default || _getOptionSpecificExcludesFor;
 
 describe("defaults", () => {
   describe("getOptionSpecificExcludesFor", () => {

packages/babel-preset-env/test/index.spec.js

@@ -7,10 +7,12 @@ import _removeRegeneratorEntryPlugin from "../lib/polyfills/regenerator.js";
 import _pluginLegacyBabelPolyfill from "../lib/polyfills/babel-polyfill.js";
 import _transformations from "../lib/module-transformations.js";
 import _availablePlugins from "../lib/available-plugins.js";
-const removeRegeneratorEntryPlugin = _removeRegeneratorEntryPlugin.default;
-const pluginLegacyBabelPolyfill = _pluginLegacyBabelPolyfill.default;
-const transformations = _transformations.default;
-const availablePlugins = _availablePlugins.default;
+const removeRegeneratorEntryPlugin =
+  _removeRegeneratorEntryPlugin.default || _removeRegeneratorEntryPlugin;
+const pluginLegacyBabelPolyfill =
+  _pluginLegacyBabelPolyfill.default || _pluginLegacyBabelPolyfill;
+const transformations = _transformations.default || _transformations;
+const availablePlugins = _availablePlugins.default || _availablePlugins;
 
 import { createRequire } from "module";
 const require = createRequire(import.meta.url);

packages/babel-preset-env/test/normalize-options.spec.js

@@ -4,7 +4,7 @@ import _normalizeOptions, {
   validateUseBuiltInsOption,
   normalizePluginName,
 } from "../lib/normalize-options.js";
-const normalizeOptions = _normalizeOptions.default;
+const normalizeOptions = _normalizeOptions.default || _normalizeOptions;
 
 describe("normalize-options", () => {
   describe("normalizeOptions", () => {

packages/babel-preset-flow/test/normalize-options.spec.js

@@ -1,5 +1,5 @@
 import _normalizeOptions from "../lib/normalize-options.js";
-const normalizeOptions = _normalizeOptions.default;
+const normalizeOptions = _normalizeOptions.default || _normalizeOptions;
 
 describe("normalize options", () => {
   (process.env.BABEL_8_BREAKING ? describe : describe.skip)("Babel 8", () => {