fix(plugin-lighthouse): prevent cleanup permissions error on windows

packages/plugin-lighthouse/src/lib/runner/runner.ts

@@ -12,13 +12,14 @@ import {
   getConfig,
   normalizeAuditOutputs,
   toAuditOutputs,
+  withLocalTmpDir,
 } from './utils.js';
 
 export function createRunnerFunction(
   urls: string[],
   flags: LighthouseCliFlags = DEFAULT_CLI_FLAGS,
 ): RunnerFunction {
-  return async (): Promise<AuditOutputs> => {
+  return withLocalTmpDir(async (): Promise<AuditOutputs> => {
     const config = await getConfig(flags);
     const normalizationFlags = enrichFlags(flags);
     const isSingleUrl = !shouldExpandForUrls(urls.length);
@@ -58,7 +59,7 @@ export function createRunnerFunction(
       );
     }
     return normalizeAuditOutputs(allResults, normalizationFlags);
-  };
+  });
 }
 
 async function runLighthouseForUrl(

packages/plugin-lighthouse/src/lib/runner/utils.ts

@@ -6,13 +6,17 @@ import experimentalConfig from 'lighthouse/core/config/experimental-config.js';
 import perfConfig from 'lighthouse/core/config/perf-config.js';
 import type Details from 'lighthouse/types/lhr/audit-details';
 import type { Result } from 'lighthouse/types/lhr/audit-result';
+import os from 'node:os';
+import path from 'node:path';
 import type { AuditOutput, AuditOutputs } from '@code-pushup/models';
 import {
   formatReportScore,
   importModule,
+  pluginWorkDir,
   readJsonFile,
   ui,
 } from '@code-pushup/utils';
+import { LIGHTHOUSE_PLUGIN_SLUG } from '../constants.js';
 import type { LighthouseOptions } from '../types.js';
 import { logUnsupportedDetails, toAuditDetails } from './details/details.js';
 import type { LighthouseCliFlags } from './types.js';
@@ -167,3 +171,31 @@ export function enrichFlags(
     outputPath: urlSpecificOutputPath,
   };
 }
+
+/**
+ * Wraps Lighthouse runner with `TEMP` directory override for Windows, to prevent permissions error on cleanup.
+ *
+ * `Runtime error encountered: EPERM, Permission denied: \\?\C:\Users\RUNNER~1\AppData\Local\Temp\lighthouse.57724617 '\\?\C:\Users\RUNNER~1\AppData\Local\Temp\lighthouse.57724617'`
+ *
+ * @param fn Async function which runs Lighthouse.
+ * @returns Wrapped function which overrides `TEMP` environment variable, before cleaning up afterwards.
+ */
+export function withLocalTmpDir<T>(fn: () => Promise<T>): () => Promise<T> {
+  if (os.platform() !== 'win32') {
+    return fn;
+  }
+
+  return async () => {
+    const originalTmpDir = process.env['TEMP'];
+    process.env['TEMP'] = path.join(
+      pluginWorkDir(LIGHTHOUSE_PLUGIN_SLUG),
+      'tmp',
+    );
+
+    try {
+      return await fn();
+    } finally {
+      process.env['TEMP'] = originalTmpDir;
+    }
+  };
+}

packages/plugin-lighthouse/src/lib/runner/utils.unit.test.ts

@@ -4,6 +4,7 @@ import log from 'lighthouse-logger';
 import type Details from 'lighthouse/types/lhr/audit-details';
 import type { Result } from 'lighthouse/types/lhr/audit-result';
 import { vol } from 'memfs';
+import os from 'node:os';
 import path from 'node:path';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import {
@@ -22,6 +23,7 @@ import {
   getConfig,
   normalizeAuditOutputs,
   toAuditOutputs,
+  withLocalTmpDir,
 } from './utils.js';
 
 // mock bundleRequire inside importEsmModule used for fetching config
@@ -502,3 +504,63 @@ describe('enrichFlags', () => {
     });
   });
 });
+
+describe('withLocalTmpDir', () => {
+  it('should return unchanged function on Linux', () => {
+    vi.spyOn(os, 'platform').mockReturnValue('linux');
+    const runner = vi.fn().mockResolvedValue('result');
+
+    expect(withLocalTmpDir(runner)).toBe(runner);
+  });
+
+  it('should return unchanged function on MacOS', () => {
+    vi.spyOn(os, 'platform').mockReturnValue('darwin');
+    const runner = vi.fn().mockResolvedValue('result');
+
+    expect(withLocalTmpDir(runner)).toBe(runner);
+  });
+
+  it('should wrap function on Windows', async () => {
+    vi.spyOn(os, 'platform').mockReturnValue('win32');
+    const runner = vi.fn().mockResolvedValue('result');
+
+    const transformed = withLocalTmpDir(runner);
+
+    expect(transformed).not.toBe(runner);
+    await expect(transformed()).resolves.toBe('result');
+    expect(runner).toHaveBeenCalled();
+  });
+
+  it('should override TEMP environment variable before function call', async () => {
+    vi.spyOn(os, 'platform').mockReturnValue('win32');
+    const runner = vi
+      .fn()
+      .mockImplementation(
+        async () => `TEMP directory is ${process.env['TEMP']}`,
+      );
+
+    await expect(withLocalTmpDir(runner)()).resolves.toBe(
+      `TEMP directory is ${path.join('node_modules', '.code-pushup', 'lighthouse', 'tmp')}`,
+    );
+  });
+
+  it('should reset TEMP environment variable after function resolves', async () => {
+    const originalTmpDir = String.raw`\\?\C:\Users\RUNNER~1\AppData\Local\Temp`;
+    const runner = vi.fn().mockResolvedValue('result');
+    vi.spyOn(os, 'platform').mockReturnValue('win32');
+    vi.stubEnv('TEMP', originalTmpDir);
+
+    await withLocalTmpDir(runner)();
+
+    expect(process.env['TEMP']).toBe(originalTmpDir);
+  });
+
+  it('should reset TEMP environment variable after function rejects', async () => {
+    const runner = vi.fn().mockRejectedValue('error');
+    vi.spyOn(os, 'platform').mockReturnValue('win32');
+    vi.stubEnv('TEMP', '');
+
+    await expect(withLocalTmpDir(runner)()).rejects.toBe('error');
+    expect(process.env['TEMP']).toBe('');
+  });
+});