test(e2e): isolate build/ rstest spawns to per-fixture cwd (#1247)

Author: fi3ework

.agents/skills/testing/SKILL.md

@@ -79,6 +79,16 @@ Important:
 - Keep fixtures minimal and representative of the behavior under test
 - Don't create near-duplicate fixtures just to add one extra test case
 
+## E2E rstest spawns with persistent `dist/.rstest-temp/`
+
+A fixture that enables `performance.buildCache` (or `dev.writeToDisk: true`) forces rstest to persist the built bundle under `<cwd>/dist/.rstest-temp/`. If sibling test files share that `cwd`, those persistent writes race against any test asserting on the default path. Other disk writers like coverage or blob reporters land in `<cwd>/coverage/` or `<cwd>/.rstest-reports/` — different surfaces, not covered by this rule.
+
+When your fixture enables persistent build output:
+
+- Set `cwd` to the fixture subdirectory, not the parent test directory.
+- In that fixture's config, drop any `include` referencing paths outside the fixture (e.g. `'./fixtures/<name>/index.test.ts'`). Fixture-local globs like `'./*.test.ts'` are fine.
+- Read `dist/.rstest-temp/` assertions from that isolated fixture dir, not from a shared parent.
+
 ## Snapshot policy
 
 - Only update snapshots when the behavioral change is **intentional**

e2e/build/buildCache.test.ts

@@ -11,9 +11,9 @@ describe('test build cache config', () => {
   it('should enable build cache with rstest-aware dependencies and keep warm runs measurable', async ({
     onTestFinished,
   }) => {
-    const fixtureName = 'buildCache';
-    const cacheDir = join(__dirname, '.cache/build-cache-fixture');
-    const outputDir = join(__dirname, 'dist/.rstest-temp');
+    const fixtureDir = join(__dirname, 'fixtures/buildCache');
+    const cacheDir = join(fixtureDir, '.cache/build-cache-fixture');
+    const outputDir = join(fixtureDir, 'dist/.rstest-temp');
     const inspectDir = join(outputDir, '.rsbuild');
 
     fs.rmSync(cacheDir, { recursive: true, force: true });
@@ -23,16 +23,11 @@ describe('test build cache config', () => {
       const start = Date.now();
       const result = await runRstestCli({
         command: 'rstest',
-        args: [
-          'run',
-          `fixtures/${fixtureName}`,
-          '-c',
-          `fixtures/${fixtureName}/rstest.config.mts`,
-        ],
+        args: ['run'],
         onTestFinished,
         options: {
           nodeOptions: {
-            cwd: __dirname,
+            cwd: fixtureDir,
             env: {
               DEBUG: 'rstest',
             },
@@ -75,25 +70,20 @@ describe('test build cache config', () => {
   it('should collect happy-dom build cache timing data on a non-trivial fixture', async ({
     onTestFinished,
   }) => {
-    const fixtureName = 'happyDomBuildCache';
-    const cacheDir = join(__dirname, '.cache/happy-dom-build-cache');
+    const fixtureDir = join(__dirname, 'fixtures/happyDomBuildCache');
+    const cacheDir = join(fixtureDir, '.cache/happy-dom-build-cache');
 
     fs.rmSync(cacheDir, { recursive: true, force: true });
 
     const runWithTiming = async () => {
       const start = Date.now();
       const result = await runRstestCli({
         command: 'rstest',
-        args: [
-          'run',
-          `fixtures/${fixtureName}`,
-          '-c',
-          `fixtures/${fixtureName}/rstest.config.mts`,
-        ],
+        args: ['run'],
         onTestFinished,
         options: {
           nodeOptions: {
-            cwd: __dirname,
+            cwd: fixtureDir,
           },
         },
       });
@@ -118,24 +108,19 @@ describe('test build cache config', () => {
   it('should keep virtual module mocks stable across cold and warm build cache runs', async ({
     onTestFinished,
   }) => {
-    const fixtureName = 'mockBuildCache';
-    const cacheDir = join(__dirname, '.cache/mock-build-cache');
+    const fixtureDir = join(__dirname, 'fixtures/mockBuildCache');
+    const cacheDir = join(fixtureDir, '.cache/mock-build-cache');
 
     fs.rmSync(cacheDir, { recursive: true, force: true });
 
     const runFixture = async () => {
       const result = await runRstestCli({
         command: 'rstest',
-        args: [
-          'run',
-          `fixtures/${fixtureName}`,
-          '-c',
-          `fixtures/${fixtureName}/rstest.config.mts`,
-        ],
+        args: ['run'],
         onTestFinished,
         options: {
           nodeOptions: {
-            cwd: __dirname,
+            cwd: fixtureDir,
           },
         },
       });

e2e/build/fixtures/buildCache/rstest.config.mts

@@ -1,7 +1,6 @@
 import { defineConfig } from '@rstest/core';
 
 export default defineConfig({
-  include: ['./fixtures/buildCache/index.test.ts'],
   performance: {
     buildCache: {
       cacheDirectory: '.cache/build-cache-fixture',

e2e/build/fixtures/happyDomBuildCache/rstest.config.mts

@@ -1,13 +1,11 @@
 import { defineConfig } from '@rstest/core';
 
 export default defineConfig({
-  include: ['./fixtures/happyDomBuildCache/index.test.ts'],
   testEnvironment: 'happy-dom',
   performance: {
     buildCache: {
       cacheDirectory: '.cache/happy-dom-build-cache',
       cacheDigest: ['happy-dom-fixture'],
-      buildDependencies: ['./fixtures/happyDomBuildCache/rstest.config.mts'],
     },
   },
 });

e2e/build/index.test.ts

@@ -17,18 +17,16 @@ describe('test build config', () => {
   ])(
     '$name config should work correctly',
     async ({ name }, { onTestFinished }) => {
+      // Run each fixture inside its own directory so the default output path
+      // (dist/.rstest-temp) is scoped to that fixture and never collides with
+      // sibling test files that also spawn rstest under e2e/build/.
       const { expectExecSuccess } = await runRstestCli({
         command: 'rstest',
-        args: [
-          'run',
-          `fixtures/${name}`,
-          '-c',
-          `fixtures/${name}/rstest.config.mts`,
-        ],
+        args: ['run'],
         onTestFinished,
         options: {
           nodeOptions: {
-            cwd: __dirname,
+            cwd: join(__dirname, 'fixtures', name),
           },
         },
       });
@@ -40,28 +38,23 @@ describe('test build config', () => {
   it('should write output to customized distPath.root', async ({
     onTestFinished,
   }) => {
-    const defaultOutputPath = join(__dirname, 'dist/.rstest-temp');
-    const customOutputPath = join(__dirname, 'custom/.rstest-temp');
+    const fixtureDir = join(__dirname, 'fixtures/customOutput');
+    const defaultOutputPath = join(fixtureDir, 'dist/.rstest-temp');
+    const customOutputPath = join(fixtureDir, 'custom/.rstest-temp');
 
     fs.rmSync(defaultOutputPath, { recursive: true, force: true });
-    fs.rmSync(join(__dirname, 'custom'), {
+    fs.rmSync(join(fixtureDir, 'custom'), {
       recursive: true,
       force: true,
     });
-    fs.rmSync(join(defaultOutputPath, 'rstest-manifest.json'), { force: true });
 
     const { expectExecSuccess } = await runRstestCli({
       command: 'rstest',
-      args: [
-        'run',
-        'fixtures/customOutput',
-        '-c',
-        'fixtures/customOutput/rstest.config.mts',
-      ],
+      args: ['run'],
       onTestFinished,
       options: {
         nodeOptions: {
-          cwd: __dirname,
+          cwd: fixtureDir,
         },
       },
     });