feat(core): replace esbuild with rolldown for mutator bundling

thesebas · thesebas · commit f53855d21bd8 · 2026-06-19T16:57:09.000+02:00
diff --git a/bun.lock b/bun.lock
diff --git a/packages/core/package.json b/packages/core/package.json
@@ -27,11 +27,11 @@
     "acorn": "^8.15.0",
     "compare-versions": "^6.1.1",
     "debug": "^4.4.3",
-    "esbuild": "^0.28.0",
     "esutils": "2.0.3",
     "fs-extra": "^11.3.2",
     "jiti": "^2.6.1",
     "remeda": "^2.33.6",
+    "rolldown": "^1.0.0",
     "tinyglobby": "^0.2.16",
     "typedoc": "^0.28.19"
   },
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/alias-resolution-tests/mutation.ts b/packages/core/src/generators/__tests__/mutator-test-files/alias-resolution-tests/mutation.ts
@@ -0,0 +1 @@
+export { default } from '@mutator-alias';
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/alias-resolution-tests/mutator-alias.d.ts b/packages/core/src/generators/__tests__/mutator-test-files/alias-resolution-tests/mutator-alias.d.ts
@@ -0,0 +1,3 @@
+declare module '@mutator-alias' {
+  export { default } from '../default-anonymous-function-2-args';
+}
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/call-expression-tests/factory-default-export.ts b/packages/core/src/generators/__tests__/mutator-test-files/call-expression-tests/factory-default-export.ts
@@ -1,8 +1,7 @@
 /* eslint-disable @typescript-eslint/no-unused-vars */
 // Regression fixture for https://github.com/orval-labs/orval/issues/3402:
-// a default export whose initializer is a CallExpression. esbuild lowers
-// `export default <expr>` into a variable declarator + named-export
-// specifier, so this exercises the same code path as the named-export
-// variant.
+// a default export whose initializer is a CallExpression. Bundled output can
+// lower `export default <expr>` into a variable declarator + named-export
+// specifier, so this exercises the same code path as the named-export variant.
 const make = (cfg: object) => (req: object) => Promise.resolve(req);
 export default make({});
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/dynamic-import-tests/dynamic-import-named-export.ts b/packages/core/src/generators/__tests__/mutator-test-files/dynamic-import-tests/dynamic-import-named-export.ts
@@ -1,8 +1,8 @@
 /* eslint-disable @typescript-eslint/no-unused-vars */
 // Mutator that performs a dynamic import in its body.
 // Regression fixture for https://github.com/orval-labs/orval/issues/1634:
-// esbuild preserves dynamic `import()` in ESM output even when targeting es6,
-// so the bundled code parsed by acorn contains an `import()` expression.
+// Bundled ESM output can preserve dynamic `import()`, so the code parsed by
+// acorn contains an `import()` expression.
 export const customInstance = async <T>(_config: {
   url: string;
 }): Promise<T> => {
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/external-package-subpath-tests/modules.d.ts b/packages/core/src/generators/__tests__/mutator-test-files/external-package-subpath-tests/modules.d.ts
@@ -0,0 +1,2 @@
+declare module 'external-package/subpath';
+declare module '@scope/pkg/runtime';
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/external-package-subpath-tests/mutation.ts b/packages/core/src/generators/__tests__/mutator-test-files/external-package-subpath-tests/mutation.ts
@@ -0,0 +1,4 @@
+import 'external-package/subpath';
+
+// eslint-disable-next-line @typescript-eslint/no-unused-vars, @typescript-eslint/no-empty-function
+export default function customInstance(_config: unknown) {}
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/external-package-subpath-tests/scoped-mutation.ts b/packages/core/src/generators/__tests__/mutator-test-files/external-package-subpath-tests/scoped-mutation.ts
@@ -0,0 +1,4 @@
+import '@scope/pkg/runtime';
+
+// eslint-disable-next-line @typescript-eslint/no-unused-vars, @typescript-eslint/no-empty-function
+export default function customInstance(_config: unknown) {}
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/external-wildcard-tests/mutation.ts b/packages/core/src/generators/__tests__/mutator-test-files/external-wildcard-tests/mutation.ts
@@ -0,0 +1,4 @@
+import './styles.scss';
+
+// eslint-disable-next-line @typescript-eslint/no-unused-vars, @typescript-eslint/no-empty-function
+export default function customInstance(_config: unknown) {}
diff --git a/packages/core/src/generators/__tests__/mutator-test-files/external-wildcard-tests/styles.d.ts b/packages/core/src/generators/__tests__/mutator-test-files/external-wildcard-tests/styles.d.ts
@@ -0,0 +1 @@
+declare module '*.scss';
diff --git a/packages/core/src/generators/mutator-info.test.ts b/packages/core/src/generators/mutator-info.test.ts
@@ -260,10 +260,80 @@ describe('getMutatorInfo', () => {
     });
   });
 
+  describe('alias resolution', () => {
+    it('should resolve aliased mutator imports', async () => {
+      const result = await getMutatorInfo(
+        path.join(basePath, 'alias-resolution-tests', 'mutation.ts'),
+        {
+          alias: {
+            '@mutator-alias': path.join(
+              basePath,
+              'default-anonymous-function-2-args.ts',
+            ),
+          },
+          external: [],
+        },
+      );
+
+      expect(result).toEqual({ numberOfParams: 2 });
+    });
+
+    it('should resolve aliased mutator imports without explicit externals', async () => {
+      const result = await getMutatorInfo(
+        path.join(basePath, 'alias-resolution-tests', 'mutation.ts'),
+        {
+          alias: {
+            '@mutator-alias': path.join(
+              basePath,
+              'default-anonymous-function-2-args.ts',
+            ),
+          },
+        },
+      );
+
+      expect(result).toEqual({ numberOfParams: 2 });
+    });
+  });
+
+  describe('external wildcards', () => {
+    it('should support wildcard external patterns', async () => {
+      const result = await getMutatorInfo(
+        path.join(basePath, 'external-wildcard-tests', 'mutation.ts'),
+        { external: ['*.scss'] },
+      );
+
+      expect(result).toEqual({ numberOfParams: 1 });
+    });
+  });
+
+  describe('external package subpaths', () => {
+    it('should externalize package subpaths from package externals', async () => {
+      const result = await getMutatorInfo(
+        path.join(basePath, 'external-package-subpath-tests', 'mutation.ts'),
+        { external: ['external-package'] },
+      );
+
+      expect(result).toEqual({ numberOfParams: 1 });
+    });
+
+    it('should externalize scoped package subpaths from scoped package externals', async () => {
+      const result = await getMutatorInfo(
+        path.join(
+          basePath,
+          'external-package-subpath-tests',
+          'scoped-mutation.ts',
+        ),
+        { external: ['@scope/pkg'] },
+      );
+
+      expect(result).toEqual({ numberOfParams: 1 });
+    });
+  });
+
   describe('dynamic import', () => {
     // Regression test for https://github.com/orval-labs/orval/issues/1634.
-    // esbuild preserves dynamic `import()` in its ESM output, so the bundled
-    // code handed to acorn contains an `import()` expression. Acorn must be
+    // The bundled ESM output can preserve dynamic `import()`, so the code
+    // handed to acorn can contain an `import()` expression. Acorn must be
     // able to parse it; otherwise the named export is reported as missing.
     it('should find named export when body contains await import()', async () => {
       const result = await getMutatorInfo(
diff --git a/packages/core/src/generators/mutator-info.ts b/packages/core/src/generators/mutator-info.ts
@@ -1,6 +1,8 @@
+import path from 'node:path';
+
 import { Parser, type Program } from 'acorn';
-import { build, type BuildOptions } from 'esbuild';
 import { isArray } from 'remeda';
+import { type ExternalOption, rolldown } from 'rolldown';
 
 import type { GeneratorMutatorParsingInfo, Tsconfig } from '../types';
 
@@ -40,39 +42,85 @@ async function bundleFile(
   external?: string[],
   compilerOptions?: Tsconfig['compilerOptions'],
 ): Promise<string> {
-  const result = await build({
-    absWorkingDir: root,
-    entryPoints: [fileName],
-    write: false,
+  const bundle = await rolldown({
+    cwd: root,
+    input: fileName,
     platform: 'node',
-    bundle: true,
-    format: 'esm',
-    metafile: false,
-    target: compilerOptions?.target ?? 'es6',
-    minify: false,
-    minifyIdentifiers: false,
-    minifySyntax: false,
-    minifyWhitespace: false,
-    treeShaking: false,
-    keepNames: false,
-    alias,
-    external: external ?? ['*'],
-  } satisfies BuildOptions);
-  const { text } = result.outputFiles[0];
+    external: getExternalOption(fileName, external, alias),
+    resolve: alias ? { alias } : undefined,
+    treeshake: false,
+    transform: {
+      target: compilerOptions?.target ?? 'es2015',
+    },
+  });
+
+  try {
+    const result = await bundle.generate({
+      format: 'esm',
+      sourcemap: false,
+    });
+    const chunk = result.output.find((output) => output.type === 'chunk');
+
+    if (!chunk) {
+      throw new Error(`Rolldown did not generate a chunk for ${fileName}`);
+    }
+
+    return chunk.code;
+  } finally {
+    await bundle.close();
+  }
+}
 
-  return text;
+function getExternalOption(
+  entry: string,
+  external?: string[],
+  alias?: Record<string, string>,
+): ExternalOption {
+  if (external) {
+    return (id) => external.some((pattern) => matchesExternal(pattern, id));
+  }
+
+  const aliasKeys = Object.keys(alias ?? {});
+
+  return (id, _parentId, isResolved) =>
+    !isResolved &&
+    id !== entry &&
+    !aliasKeys.some((key) => id === key || id.startsWith(`${key}/`));
+}
+
+function matchesExternal(pattern: string, id: string): boolean {
+  if (pattern === id) {
+    return true;
+  }
+
+  if (isPackagePattern(pattern) && id.startsWith(`${pattern}/`)) {
+    return true;
+  }
+
+  const regex = new RegExp(
+    `^${pattern.replaceAll(/[$()+./?[\\\]^{|}]/g, String.raw`\$&`).replaceAll('*', '.*')}$`,
+  );
+
+  return regex.test(id);
+}
+
+function isPackagePattern(pattern: string): boolean {
+  return (
+    !pattern.startsWith('.') &&
+    !path.isAbsolute(pattern) &&
+    !pattern.includes('*')
+  );
 }
 
 function parseFile(
   file: string,
   name: string,
 ): GeneratorMutatorParsingInfo | undefined {
   try {
-    // `file` is esbuild's bundled output, not the user's source. esbuild may
-    // emit any modern syntax (notably dynamic `import()`, which it preserves
-    // even when targeting es6 in ESM mode), so we parse with the latest
-    // ecmaVersion to avoid spurious SyntaxErrors that would mask the export
-    // we are looking for. See https://github.com/orval-labs/orval/issues/1634.
+    // `file` is bundled output, not the user's source. The bundler may emit
+    // modern syntax, so we parse with the latest ecmaVersion to avoid spurious
+    // SyntaxErrors that would mask the export we are looking for.
+    // See https://github.com/orval-labs/orval/issues/1634.
     const ast = Parser.parse(file, {
       ecmaVersion: 'latest',
       sourceType: 'module',

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+export { default } from '@mutator-alias';`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+declare module '@mutator-alias' {`
	`2`	`+ export { default } from '../default-anonymous-function-2-args';`
	`3`	`+}`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+declare module 'external-package/subpath';`
	`2`	`+declare module '@scope/pkg/runtime';`