apm-js-collab · isaacs · Jun 18, 2026 · Jun 18, 2026
diff --git a/package.json b/package.json
@@ -83,7 +83,7 @@
         "access": "public"
     },
     "dependencies": {
-        "@apm-js-collab/code-transformer": "^0.14.0",
+        "@apm-js-collab/code-transformer": "^0.15.0",
         "es-module-lexer": "^2.1.0",
         "module-details-from-path": "^1.0.4",
         "magic-string": "^0.30.21"

diff --git a/src/core.ts b/src/core.ts
@@ -172,7 +172,7 @@ export function createCodeTransformer(options: CodeTransformerPluginOptions) {
   const transform = (
     code: string,
     id: string,
-    inputSourceMap?: string | null,
+    inputSourceMap?: string | object | null,
   ): TransformResult | null => {
     const moduleDetails = moduleDetailsFromPath(id);
     if (!moduleDetails) return null;
@@ -208,7 +208,7 @@ export function createCodeTransformer(options: CodeTransformerPluginOptions) {
       transformedModules.add(transformer.moduleName);
       return { code: result.code, map: result.map };
     } catch (error) {
-      console.warn(`Code transformation failed for ${id}: ${error}`);
+      console.warn(`Code transformation failed for '${id}'`, error);
       failedModules.add(moduleDetails.name);
       return null;
     }

diff --git a/src/rollup.ts b/src/rollup.ts
@@ -1,4 +1,4 @@
-import type { Plugin } from "rollup";
+import type { OutputOptions, Plugin, TransformPluginContext } from "rollup";
 import {
   COMMENT_USE_STRICT_REGEX,
   createCodeTransformer,
@@ -13,12 +13,18 @@ export default function codeTransformerRollup(
 ): Plugin {
   const { transform: transformCode, getCodeToInject } =
     createCodeTransformer(options);
+
+  let sourcemapsEnabled = false;
+
+  const outputOptions = (inputOptions: OutputOptions) => {
+    sourcemapsEnabled = !!inputOptions.sourcemap; 
+  };
 
   const renderChunk = (
     code: string,
     chunk: { fileName: string; facadeModuleId?: string | null },
     _?: unknown,
-    meta?: { magicString?: MagicString },
+    meta?: { magicString?: MagicString, chunks: unknown },
   ): {
     code: string;
     map?: SourceMap;
@@ -68,8 +74,9 @@ export default function codeTransformerRollup(
     };
   };
 
-  const transform = (code: string, id: string) => {
-    const result = transformCode(code, id);
+  function transform(this: TransformPluginContext, code: string, id: string) {
+    const inputSourceMap = sourcemapsEnabled ? this.getCombinedSourcemap() : undefined;
+    const result = transformCode(code, id, inputSourceMap);
     if (!result) return null;
     return { code: result.code, map: result.map ?? null };
   };
@@ -79,14 +86,16 @@ export default function codeTransformerRollup(
   if (!options.injectDiagnostics) {
     return {
       name,
+      outputOptions,
       transform,
     };
   }
 
   return {
     name,
+    outputOptions,
     transform,
-    renderChunk: renderChunk as unknown as Plugin["renderChunk"],
+    renderChunk,
   };
 }
 

diff --git a/test/vite.test.ts b/test/vite.test.ts
@@ -5,6 +5,7 @@ import { join } from 'path';
 import { writeFileSync, mkdirSync } from 'fs';
 import { createTestFixture, commonTestCases, type TestFixture } from './test-utils.js';
 import { builtinModules } from 'module';
+import MagicString from 'magic-string';
 
 describe('Vite integration tests', () => {
     let fixture: TestFixture;
@@ -144,12 +145,12 @@ export function testFunction() {
                 channelName: 'test:channel',
                 module: {
                     name: 'test-module',
-                    versionRange: '>=1.0.0' as any,
+                    versionRange: '>=1.0.0',
                     filePath: 'outside.js'
                 },
                 functionQuery: {
                     functionName: 'testFunction',
-                    kind: 'Async' as const
+                    kind: 'Async'
                 }
             }]
         });
@@ -184,7 +185,7 @@ export function testFunction() {
                 ...testCase.instrumentation,
                 module: {
                     ...testCase.instrumentation.module,
-                    versionRange: '>=2.0.0' as any // Version doesn't match (module is 1.2.3)
+                    versionRange: '>=2.0.0'
                 }
             }]
         });
@@ -209,6 +210,87 @@ export function testFunction() {
         }
     });
 
+    it('should generate a sourcemap when sourcemaps are enabled', async () => {
+        const testCase = commonTestCases.esmodule;
+        const testFile = join(fixture.moduleDir, testCase.filename);
+        writeFileSync(testFile, testCase.code);
+
+        const plugin = codeTransformerPlugin({
+            instrumentations: [testCase.instrumentation]
+        });
+
+        const result = await build({
+            root: fixture.testDir,
+            build: {
+                write: false,
+                sourcemap: true,
+                rollupOptions: {
+                    input: testFile,
+                    external: Array.from(builtinModules)
+                }
+            },
+            plugins: [plugin]
+        });
+
+        expect(result).toBeDefined();
+        if ('output' in result) {
+            const chunk = result.output.find(o => o.type === 'chunk');
+            expect(chunk).toBeDefined();
+            if (chunk?.type === 'chunk') {
+                expect(chunk.code).toContain('test:esmodule');
+                expect(chunk.map).toBeDefined();
+                expect(chunk.map?.sources.some(s => s?.includes('esmodule.js'))).toBe(true);
+            }
+        }
+    });
+
+    it('should chain sourcemaps from a prior transform plugin', async () => {
+        const testCase = commonTestCases.esmodule;
+        const testFile = join(fixture.moduleDir, testCase.filename);
+        writeFileSync(testFile, testCase.code);
+
+        // Runs before code-transformer (same enforce tier, listed first) and shifts line numbers
+        const priorTransformPlugin = {
+            name: 'prior-transform',
+            enforce: 'pre',
+            transform(code: string, id: string) {
+                if (!id.includes('esmodule.js')) return null;
+                const ms = new MagicString(code);
+                ms.prepend('// inserted by prior transform\n');
+                return { code: ms.toString(), map: ms.generateMap({ hires: true, source: id }) };
+            }
+        };
+
+        const plugin = codeTransformerPlugin({
+            instrumentations: [testCase.instrumentation]
+        });
+
+        const result = await build({
+            root: fixture.testDir,
+            build: {
+                write: false,
+                sourcemap: true,
+                rollupOptions: {
+                    input: testFile,
+                    external: Array.from(builtinModules)
+                }
+            },
+            plugins: [priorTransformPlugin, plugin]
+        });
+
+        expect(result).toBeDefined();
+        if ('output' in result) {
+            const chunk = result.output.find(o => o.type === 'chunk');
+            expect(chunk).toBeDefined();
+            if (chunk?.type === 'chunk') {
+                expect(chunk.code).toContain('test:esmodule');
+                // Sourcemap must chain back to the original file, not the intermediate output
+                expect(chunk.map).toBeDefined();
+                expect(chunk.map?.sources.some(s => s?.includes('esmodule.js'))).toBe(true);
+            }
+        }
+    });
+
     it('should handle multiple instrumentations correctly', async () => {
         const libFile = join(fixture.moduleDir, 'lib', 'http.js');
         mkdirSync(join(fixture.moduleDir, 'lib'), { recursive: true });
@@ -232,26 +314,26 @@ export class HttpClient {
                     channelName: 'http:fetch',
                     module: {
                         name: 'test-module',
-                        versionRange: '>=1.0.0' as any,
+                        versionRange: '>=1.0.0',
                         filePath: 'lib/http.js'
                     },
                     functionQuery: {
                         className: 'HttpClient',
                         methodName: 'fetch',
-                        kind: 'Async' as const
+                        kind: 'Async'
                     }
                 },
                 {
                     channelName: 'http:post',
                     module: {
                         name: 'test-module',
-                        versionRange: '>=1.0.0' as any,
+                        versionRange: '>=1.0.0',
                         filePath: 'lib/http.js'
                     },
                     functionQuery: {
                         className: 'HttpClient',
                         methodName: 'post',
-                        kind: 'Async' as const
+                        kind: 'Async'
                     }
                 }
             ]

diff --git a/yarn.lock b/yarn.lock
@@ -2,10 +2,10 @@
 # yarn lockfile v1
 
 
-"@apm-js-collab/code-transformer@^0.14.0":
-  version "0.14.0"
-  resolved "https://registry.yarnpkg.com/@apm-js-collab/code-transformer/-/code-transformer-0.14.0.tgz#b4a43bfbc67047038eac1e276d1388285f714bbe"
-  integrity sha512-6G+FETQ/VyRBsIkDDZ5sc9fb7O6d6W9rm8bZPHumISZw/6nwxvnS+VTyxd3sKM04aZwHG5hJIHb7VPdPCLieSQ==
+"@apm-js-collab/code-transformer@^0.15.0":
+  version "0.15.0"
+  resolved "https://registry.yarnpkg.com/@apm-js-collab/code-transformer/-/code-transformer-0.15.0.tgz#a3a1b6c7b92db16f8277636b4a72a1626e2fa52a"
+  integrity sha512-XmXYVs8CzJ1Aj79noVbn2weUO/XWtRyURpGqx7aU7DOXlUQhR0WKOQNF0okh7PCeY37vxf7kU3v57OAkEPm3ww==
   dependencies:
     "@types/estree" "^1.0.8"
     astring "^1.9.0"