feat(cjs): improve compatibility with other loaders

package.json

@@ -108,6 +108,7 @@
 		"node-pty": "^1.0.0",
 		"outdent": "^0.8.0",
 		"pkgroll": "^2.1.1",
+		"proxyquire": "^2.1.3",
 		"simple-git-hooks": "^2.11.1",
 		"split2": "^4.2.0",
 		"strip-ansi": "^7.1.0",

src/cjs/api/module-extensions.ts

@@ -8,6 +8,7 @@ import { shouldApplySourceMap, inlineSourceMap } from '../../source-map.js';
 import { parent } from '../../utils/ipc/client.js';
 import { fileMatcher } from '../../utils/tsconfig.js';
 import { implicitlyResolvableExtensions } from './resolve-implicit-extensions.js';
+import type { LoaderState } from './types.js';
 
 const typescriptExtensions = [
 	'.cts',
@@ -23,22 +24,6 @@ const transformExtensions = [
 	'.mjs',
 ] as const;
 
-const cloneExtensions = <ObjectType extends object>(
-	extensions: ObjectType,
-) => {
-	const cloneTo: ObjectType = Object.create(Object.getPrototypeOf(extensions));
-
-	// Preserves setters if they exist (e.g. nyc via append-transform)
-	const descriptors = Object.getOwnPropertyDescriptors(extensions);
-	for (const property in descriptors) {
-		if (Object.hasOwn(descriptors, property)) {
-			Object.defineProperty(cloneTo, property, descriptors[property]);
-		}
-	}
-
-	return cloneTo;
-};
-
 const safeSet = <T extends Record<string, unknown>>(
 	object: T,
 	property: keyof T,
@@ -82,18 +67,20 @@ const safeSet = <T extends Record<string, unknown>>(
 };
 
 export const createExtensions = (
-	extendExtensions: NodeJS.RequireExtensions,
+	state: LoaderState,
+	extensions: NodeJS.RequireExtensions,
 	namespace?: string,
 ) => {
-	// Clone Module._extensions with null prototype
-	const extensions = cloneExtensions(extendExtensions);
-
 	const defaultLoader = extensions['.js'];
 
 	const transformer = (
 		module: Module,
 		filePath: string,
 	) => {
+		if (state.enabled === false) {
+			return defaultLoader(module, filePath);
+		}
+
 		// Make sure __filename doesnt contain query
 		const [cleanFilePath, query] = filePath.split('?');
 
@@ -198,5 +185,22 @@ export const createExtensions = (
 		configurable: true,
 	});
 
-	return extensions;
+	// Unregister
+	return () => {
+		/**
+		 * The extensions are only reverted if they're still tsx's transformers
+		 *
+		 * Otherwise, it means they have been wrapped by another loader and should
+		 * be left untouched not to remove the other loader
+		 */
+		if (extensions['.js'] === transformer) {
+			extensions['.js'] = defaultLoader;
+		}
+
+		for (const extension of [...implicitlyResolvableExtensions, '.mjs']) {
+			if (extensions[extension] === transformer) {
+				delete extensions[extension];
+			}
+		}
+	};
 };

src/cjs/api/module-resolve-filename.ts

@@ -6,7 +6,7 @@ import type { NodeError } from '../../types.js';
 import { isRelativePath, fileUrlPrefix, tsExtensionsPattern } from '../../utils/path-utils.js';
 import { tsconfigPathsMatcher, allowJs } from '../../utils/tsconfig.js';
 import { urlSearchParamsStringify } from '../../utils/url-search-params-stringify.js';
-import type { ResolveFilename, SimpleResolve } from './types.js';
+import type { ResolveFilename, SimpleResolve, LoaderState } from './types.js';
 import { createImplicitResolver } from './resolve-implicit-extensions.js';
 
 const nodeModulesPath = `${path.sep}node_modules${path.sep}`;
@@ -154,6 +154,7 @@ const resolveRequest = (
 };
 
 export const createResolveFilename = (
+	state: LoaderState,
 	nextResolve: ResolveFilename,
 	namespace?: string,
 ): ResolveFilename => (
@@ -162,6 +163,10 @@ export const createResolveFilename = (
 	isMain,
 	options,
 ) => {
+	if (state.enabled === false) {
+		return nextResolve(request, parent, isMain, options);
+	}
+
 	const resolve: SimpleResolve = request_ => nextResolve(
 		request_,
 		parent,

src/cjs/api/register.ts

@@ -4,6 +4,7 @@ import { fileURLToPath } from 'node:url';
 import { loadTsconfig } from '../../utils/tsconfig.js';
 import type { RequiredProperty } from '../../types.js';
 import { urlSearchParamsStringify } from '../../utils/url-search-params-stringify.js';
+import type { LoaderState } from './types.js';
 import { createExtensions } from './module-extensions.js';
 import { createResolveFilename } from './module-resolve-filename.js';
 
@@ -62,27 +63,35 @@ export const register: Register = (
 	options,
 ) => {
 	const { sourceMapsEnabled } = process;
-	const { _extensions, _resolveFilename } = Module;
+	const state: LoaderState = {
+		enabled: true,
+	};
 
 	loadTsconfig(process.env.TSX_TSCONFIG_PATH);
 
 	// register
 	process.setSourceMapsEnabled(true);
-	const resolveFilename = createResolveFilename(_resolveFilename, options?.namespace);
+
+	const originalResolveFilename = Module._resolveFilename;
+	const resolveFilename = createResolveFilename(state, originalResolveFilename, options?.namespace);
 	Module._resolveFilename = resolveFilename;
 
-	const extensions = createExtensions(Module._extensions, options?.namespace);
-	// @ts-expect-error overwriting read-only property
-	Module._extensions = extensions;
+	const unregisterExtensions = createExtensions(state, Module._extensions, options?.namespace);
 
 	const unregister = () => {
 		if (sourceMapsEnabled === false) {
 			process.setSourceMapsEnabled(false);
 		}
-
-		// @ts-expect-error overwriting read-only property
-		Module._extensions = _extensions;
-		Module._resolveFilename = _resolveFilename;
+		state.enabled = false;
+
+		/**
+		 * Only revert the _resolveFilename & extensions if they're unwrapped
+		 * by another loader extension
+		 */
+		if (Module._resolveFilename === resolveFilename) {
+			Module._resolveFilename = originalResolveFilename;
+		}
+		unregisterExtensions();
 	};
 
 	if (options?.namespace) {

src/cjs/api/types.ts

@@ -1,5 +1,9 @@
 import type Module from 'module';
 
+export type LoaderState = {
+	enabled: boolean;
+};
+
 export type ResolveFilename = typeof Module._resolveFilename;
 
 export type SimpleResolve = (request: string) => string;

tests/specs/api.ts

@@ -118,7 +118,7 @@ export default testSuite(({ describe }, node: NodeApis) => {
 						return code;
 					}, '.ts');
 					`,
-					node_modules: ({ symlink }) => symlink(path.resolve('node_modules'), 'junction'),
+					'node_modules/append-transform': ({ symlink }) => symlink(path.resolve('node_modules/append-transform'), 'junction'),
 				});
 
 				const { stdout } = await execaNode('./index.js', {
@@ -311,6 +311,38 @@ export default testSuite(({ describe }, node: NodeApis) => {
 
 					expect(stdout).toBe('foo bar json file.ts\nfoo bar json file.ts\nfoo bar json file.ts\nUnregistered');
 				});
+
+				test('works with proxyquire (eslint tests)', async () => {
+					await using fixture = await createFixture({
+						'index.js': `
+						const proxyquire = require('proxyquire');
+						const tsx = require(${JSON.stringify(tsxCjsApiPath)});
+						
+						tsx.register();
+						
+						proxyquire('./test.js', {
+							path: {
+								sep: 'hello world',
+							},
+						});
+						`,
+
+						'test.js': `
+						const path = require('path');
+						console.log(path.sep);
+						`,
+
+						'node_modules/proxyquire': ({ symlink }) => symlink(path.resolve('node_modules/proxyquire'), 'junction'),
+					});
+
+					const { stdout } = await execaNode('./index.js', {
+						cwd: fixture.path,
+						nodePath: node.path,
+						nodeOptions: [],
+					});
+
+					expect(stdout).toBe('hello world');
+				});
 			});
 		});