fix: @posthog/nextjs-config keeps scss files sourcemap when delete-after enabled

.changeset/soft-css-sourcemaps.md

@@ -0,0 +1,5 @@
+---
+"@posthog/webpack-plugin": patch
+---
+
+Include emitted CSS assets with adjacent source maps when processing webpack sourcemaps.

packages/webpack-plugin/jest.config.mjs

@@ -0,0 +1,12 @@
+import { createDefaultPreset } from 'ts-jest'
+
+const tsJestTransformCfg = createDefaultPreset().transform
+
+/** @type {import('jest').Config} **/
+export default {
+    testEnvironment: 'node',
+    testPathIgnorePatterns: ['/node_modules/', '/dist/'],
+    transform: {
+        ...tsJestTransformCfg,
+    },
+}

packages/webpack-plugin/package.json

@@ -34,7 +34,9 @@
     "devDependencies": {
         "@posthog-tooling/tsconfig-base": "workspace:*",
         "@rslib/core": "catalog:",
+        "@types/jest": "catalog:",
         "jest": "catalog:",
+        "ts-jest": "catalog:",
         "webpack": "^5"
     },
     "scripts": {

packages/webpack-plugin/src/index.ts

@@ -58,14 +58,24 @@ export class PosthogWebpackPlugin {
             return
         }
 
-        const filePaths: string[] = []
+        const filePaths = new Set<string>()
         chunkArray.forEach((chunk) =>
             chunk.files.forEach((file) => {
                 const chunkPath = path.resolve(outputDirectory, file)
-                filePaths.push(chunkPath)
+                filePaths.add(chunkPath)
             })
         )
 
-        await runSourcemapCli(config, { filePaths })
+        compilation.getAssets().forEach((asset) => {
+            if (asset.name.endsWith('.css')) {
+                const mapAssetName = `${asset.name}.map`
+                if (compilation.getAsset(mapAssetName)) {
+                    filePaths.add(path.resolve(outputDirectory, asset.name))
+                    filePaths.add(path.resolve(outputDirectory, mapAssetName))
+                }
+            }
+        })
+
+        await runSourcemapCli(config, { filePaths: Array.from(filePaths) })
     }
 }

packages/webpack-plugin/test/index.spec.ts

@@ -0,0 +1,70 @@
+import path from 'path'
+import type webpack from 'webpack'
+import { runSourcemapCli } from '@posthog/plugin-utils'
+import { PosthogWebpackPlugin } from '../src/index'
+import type { ResolvedPluginConfig } from '../src/config'
+
+jest.mock('@posthog/plugin-utils', () => ({
+    runSourcemapCli: jest.fn().mockResolvedValue(undefined),
+}))
+
+const runSourcemapCliMock = runSourcemapCli as jest.MockedFunction<typeof runSourcemapCli>
+
+const config: ResolvedPluginConfig = {
+    personalApiKey: 'phx_test',
+    projectId: '1',
+    host: 'https://us.i.posthog.com',
+    logLevel: 'info',
+    cliBinaryPath: 'posthog-cli',
+    sourcemaps: {
+        enabled: true,
+        deleteAfterUpload: true,
+    },
+}
+
+type TestAsset = { name: string }
+type TestChunk = { files: Set<string> }
+
+function createCompilation(outputDirectory: string, chunks: TestChunk[], assets: TestAsset[]): webpack.Compilation {
+    return {
+        outputOptions: { path: outputDirectory },
+        chunks: new Set(chunks),
+        getAssets: () => assets,
+        getAsset: (name: string) => assets.find((asset) => asset.name === name),
+    } as unknown as webpack.Compilation
+}
+
+describe('PosthogWebpackPlugin', () => {
+    beforeEach(() => {
+        runSourcemapCliMock.mockClear()
+    })
+
+    it('passes emitted CSS assets with adjacent source maps to the sourcemap CLI', async () => {
+        const outputDirectory = path.resolve('/tmp/posthog-webpack-plugin')
+        const plugin = new PosthogWebpackPlugin(config, true)
+        const compilation = createCompilation(
+            outputDirectory,
+            [
+                {
+                    files: new Set(['static/chunks/app.js', 'static/chunks/app.js.map']),
+                },
+            ],
+            [
+                { name: 'static/css/app.css' },
+                { name: 'static/css/app.css.map' },
+                { name: 'static/css/no-map.css' },
+            ]
+        )
+
+        await plugin.processSourceMaps(compilation, config)
+
+        expect(runSourcemapCliMock).toHaveBeenCalledWith(config, {
+            filePaths: [
+                path.resolve(outputDirectory, 'static/chunks/app.js'),
+                path.resolve(outputDirectory, 'static/chunks/app.js.map'),
+                path.resolve(outputDirectory, 'static/css/app.css'),
+                path.resolve(outputDirectory, 'static/css/app.css.map'),
+            ],
+        })
+    })
+})

packages/webpack-plugin/tsconfig.json

@@ -9,5 +9,6 @@
         "declarationMap": true,
         "moduleResolution": "bundler",
         "module": "ES6"
-    }
+    },
+    "include": ["src/**/*.ts"]
 }