support changed files

packages/playwright/src/util.ts

@@ -83,7 +83,9 @@ export type TestFileFilter = {
 export async function createFileFiltersFromArguments(args: string[], onlyChanged: boolean): Promise<TestFileFilter[]> {
   if (onlyChanged) {
     const untrackedFiles = childProcess.execSync('git ls-files --others --exclude-standard', { encoding: 'utf-8' }).split('\n').filter(Boolean);
-    args = untrackedFiles;
+    const changedFiles = childProcess.execSync('git diff --name-only', { encoding: 'utf-8' }).split('\n').filter(Boolean);
+
+    args = [...untrackedFiles, ...changedFiles];
   }
 
   return args.map(arg => {

tests/playwright-test/only-changed.spec.ts

@@ -19,7 +19,7 @@ import { execSync } from 'node:child_process';
 import { writeFile } from 'node:fs/promises';
 import { join } from 'node:path';
 
-test('should filter by file name', async ({ runInlineTest }) => {
+test('should detect untracked files', async ({ runInlineTest }) => {
   const result = await runInlineTest({
     'a.spec.ts': `
         import { test, expect } from '@playwright/test';
@@ -45,3 +45,32 @@ test('should filter by file name', async ({ runInlineTest }) => {
   expect(result.failed).toBe(1);
   expect(result.output).toContain('c.spec.ts');
 });
+
+
+test('should detect changed files', async ({ runInlineTest }) => {
+  const result = await runInlineTest({
+    'a.spec.ts': `
+        import { test, expect } from '@playwright/test';
+        test('fails', () => { expect(1).toBe(2); });
+      `,
+    'b.spec.ts': `
+        import { test, expect } from '@playwright/test';
+        test('fails', () => { expect(1).toBe(2); });
+      `,
+    async [magicFileCreationSymbol](baseDir) {
+      execSync(`git init --initial-branch=main`, { cwd: baseDir });
+      execSync(`git add .`, { cwd: baseDir });
+      execSync(`git commit -m init`, { cwd: baseDir });
+
+      await writeFile(join(baseDir, 'b.spec.ts'), `
+        import { test, expect } from '@playwright/test';
+        test('fails', () => { expect(1).toBe(3); });
+      `);
+    }
+  }, { 'only-changed': true });
+
+  expect(result.exitCode).toBe(1);
+  expect(result.failed).toBe(1);
+  expect(result.output).toContain('b.spec.ts');
+});
+