test: add tests for transform (#397)

package.json

@@ -75,11 +75,13 @@
 		"eslint": "^8.49.0",
 		"execa": "^8.0.1",
 		"fs-fixture": "^1.2.0",
+		"fs-require": "^1.6.0",
 		"get-node": "^14.2.1",
 		"kolorist": "^1.8.0",
 		"lint-staged": "^14.0.1",
 		"magic-string": "^0.30.3",
 		"manten": "^1.2.0",
+		"memfs": "^4.6.0",
 		"node-pty": "^1.0.0",
 		"outdent": "^0.8.0",
 		"pkgroll": "^1.11.1",

src/utils/transform/get-esbuild-options.ts

@@ -1,50 +1,63 @@
 import path from 'path';
-import type { TransformOptions } from 'esbuild';
-
-const nodeVersion = process.versions.node;
+import type { TransformOptions, TransformResult } from 'esbuild';
+
+export const baseConfig = Object.freeze({
+	target: `node${process.versions.node}`,
+
+	// "default" tells esbuild to infer loader from file name
+	// https://github.com/evanw/esbuild/blob/4a07b17adad23e40cbca7d2f8931e8fb81b47c33/internal/bundler/bundler.go#L158
+	loader: 'default',
+});
+
+export const cacheConfig = {
+	...baseConfig,
+
+	sourcemap: true,
+
+	/**
+	 * Smaller output for cache and marginal performance improvement:
+	 * https://twitter.com/evanwallace/status/1396336348366180359?s=20
+	 *
+	 * minifyIdentifiers is disabled because debuggers don't use the
+	 * `names` property from the source map
+	 *
+	 * minifySyntax is disabled because it does some tree-shaking
+	 * eg. unused try-catch error variable
+	 */
+	minifyWhitespace: true,
+
+	// TODO: Is this necessary if minifyIdentifiers is false?
+	keepNames: true,
+};
 
-export const getEsbuildOptions = (
-	extendOptions: TransformOptions,
+export const patchOptions = (
+	options: TransformOptions,
 ) => {
-	const options: TransformOptions = {
-		target: `node${nodeVersion}`,
-
-		// "default" tells esbuild to infer loader from file name
-		// https://github.com/evanw/esbuild/blob/4a07b17adad23e40cbca7d2f8931e8fb81b47c33/internal/bundler/bundler.go#L158
-		loader: 'default',
-
-		sourcemap: true,
-
-		/**
-		 * Smaller output for cache and marginal performance improvement:
-		 * https://twitter.com/evanwallace/status/1396336348366180359?s=20
-		 *
-		 * minifyIdentifiers is disabled because debuggers don't use the
-		 * `names` property from the source map
-		 *
-		 * minifySyntax is disabled because it does some tree-shaking
-		 * eg. unused try-catch error variable
-		 */
-		minifyWhitespace: true,
-		keepNames: true,
-
-		...extendOptions,
-	};
+	const originalSourcefile = options.sourcefile;
 
-	if (options.sourcefile) {
-		const { sourcefile } = options;
-		const extension = path.extname(sourcefile);
+	if (originalSourcefile) {
+		const extension = path.extname(originalSourcefile);
 
 		if (extension) {
 			// https://github.com/evanw/esbuild/issues/1932
 			if (extension === '.cts' || extension === '.mts') {
-				options.sourcefile = `${sourcefile.slice(0, -3)}ts`;
+				options.sourcefile = `${originalSourcefile.slice(0, -3)}ts`;
 			}
 		} else {
 			// esbuild errors to detect loader when a file doesn't have an extension
 			options.sourcefile += '.js';
 		}
 	}
 
-	return options;
+	return (
+		result: TransformResult,
+	) => {
+		if (options.sourcefile !== originalSourcefile) {
+			result.map = result.map.replace(
+				JSON.stringify(options.sourcefile),
+				JSON.stringify(originalSourcefile),
+			);
+		}
+		return result;
+	};
 };

src/utils/transform/index.ts

@@ -13,7 +13,10 @@ import {
 	applyTransformers,
 	type Transformed,
 } from './apply-transformers';
-import { getEsbuildOptions } from './get-esbuild-options';
+import {
+	cacheConfig,
+	patchOptions,
+} from './get-esbuild-options';
 
 // Used by cjs-loader
 export function transformSync(
@@ -27,14 +30,15 @@ export function transformSync(
 		define['import.meta.url'] = `'${pathToFileURL(filePath)}'`;
 	}
 
-	const esbuildOptions = getEsbuildOptions({
+	const esbuildOptions = {
+		...cacheConfig,
 		format: 'cjs',
 		sourcefile: filePath,
 		define,
 		banner: '(()=>{',
 		footer: '})()',
 		...extendOptions,
-	});
+	} as const;
 
 	const hash = sha1([
 		code,
@@ -50,16 +54,11 @@ export function transformSync(
 			code,
 			[
 				// eslint-disable-next-line @typescript-eslint/no-shadow
-				(filePath, code) => {
-					// eslint-disable-next-line @typescript-eslint/no-shadow
-					const transformed = esbuildTransformSync(code, esbuildOptions);
-					if (esbuildOptions.sourcefile !== filePath) {
-						transformed.map = transformed.map.replace(
-							JSON.stringify(esbuildOptions.sourcefile),
-							JSON.stringify(filePath),
-						);
-					}
-					return transformed;
+				(_filePath, code) => {
+					const patchResults = patchOptions(esbuildOptions);
+					return patchResults(
+						esbuildTransformSync(code, esbuildOptions),
+					);
 				},
 				transformDynamicImport,
 			] as const,
@@ -84,11 +83,12 @@ export async function transform(
 	filePath: string,
 	extendOptions?: TransformOptions,
 ): Promise<Transformed> {
-	const esbuildOptions = getEsbuildOptions({
+	const esbuildOptions = {
+		...cacheConfig,
 		format: 'esm',
 		sourcefile: filePath,
 		...extendOptions,
-	});
+	} as const;
 
 	const hash = sha1([
 		code,
@@ -104,16 +104,11 @@ export async function transform(
 			code,
 			[
 				// eslint-disable-next-line @typescript-eslint/no-shadow
-				async (filePath, code) => {
-					// eslint-disable-next-line @typescript-eslint/no-shadow
-					const transformed = await esbuildTransform(code, esbuildOptions);
-					if (esbuildOptions.sourcefile !== filePath) {
-						transformed.map = transformed.map.replace(
-							JSON.stringify(esbuildOptions.sourcefile),
-							JSON.stringify(filePath),
-						);
-					}
-					return transformed;
+				async (_filePath, code) => {
+					const patchResults = patchOptions(esbuildOptions);
+					return patchResults(
+						await esbuildTransform(code, esbuildOptions),
+					);
 				},
 				transformDynamicImport,
 			] as const,

tests/index.ts

@@ -8,6 +8,7 @@ import { nodeVersions } from './utils/node-versions';
 		await runTestSuite(import('./specs/watch'));
 		await runTestSuite(import('./specs/repl'));
 		await runTestSuite(import('./specs/source-map'));
+		await runTestSuite(import('./specs/transform'));
 
 		for (const nodeVersion of nodeVersions) {
 			const node = await createNode(nodeVersion);