From 2d9a299d66358d0259f937ded6e98f2727d43b5a Mon Sep 17 00:00:00 2001
From: Simon Knott <info@simonknott.de>
Date: Wed, 17 Jul 2024 11:00:28 +0200
Subject: [PATCH] allow comparison against base commit

---
 packages/playwright/src/common/config.ts   |  2 +-
 packages/playwright/src/program.ts         |  4 +--
 packages/playwright/src/util.ts            | 11 ++++----
 tests/playwright-test/only-changed.spec.ts | 29 ++++++++++++++++++++++
 4 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/packages/playwright/src/common/config.ts b/packages/playwright/src/common/config.ts
index 8786d50558..0a88fe85fd 100644
--- a/packages/playwright/src/common/config.ts
+++ b/packages/playwright/src/common/config.ts
@@ -49,7 +49,7 @@ export class FullConfigInternal {
   cliArgs: string[] = [];
   cliGrep: string | undefined;
   cliGrepInvert: string | undefined;
-  cliOnlyChanged = false;
+  cliOnlyChanged: string | boolean | undefined;
   cliProjectFilter?: string[];
   cliListOnly = false;
   cliPassWithNoTests?: boolean;
diff --git a/packages/playwright/src/program.ts b/packages/playwright/src/program.ts
index 47d8ca116d..d64de03648 100644
--- a/packages/playwright/src/program.ts
+++ b/packages/playwright/src/program.ts
@@ -192,7 +192,7 @@ async function runTests(args: string[], opts: { [key: string]: any }) {
 
   config.cliArgs = args;
   config.cliGrep = opts.grep as string | undefined;
-  config.cliOnlyChanged = !!opts.onlyChanged;
+  config.cliOnlyChanged = opts.onlyChanged as string | boolean | undefined;
   config.cliGrepInvert = opts.grepInvert as string | undefined;
   config.cliListOnly = !!opts.list;
   config.cliProjectFilter = opts.project || undefined;
@@ -353,7 +353,7 @@ const testOptions: [string, string][] = [
   ['--max-failures <N>', `Stop after the first N failures`],
   ['--no-deps', 'Do not run project dependencies'],
   ['--output <dir>', `Folder for output artifacts (default: "test-results")`],
-  ['--only-changed', `something something docs`],
+  ['--only-changed [base-commit]', `something something docs`],
   ['--pass-with-no-tests', `Makes test run succeed even if no tests were found`],
   ['--project <project-name...>', `Only run tests from the specified list of projects, supports '*' wildcard (default: run all projects)`],
   ['--quiet', `Suppress stdio`],
diff --git a/packages/playwright/src/util.ts b/packages/playwright/src/util.ts
index a21b06c9b1..373e89963a 100644
--- a/packages/playwright/src/util.ts
+++ b/packages/playwright/src/util.ts
@@ -80,16 +80,17 @@ export type TestFileFilter = {
   column: number | null;
 };
 
-export async function detectChangedFiles(): Promise<string[]> {
+export async function detectChangedFiles(onlyChangedParam: string | true): Promise<string[]> {
+  const baseCommit = onlyChangedParam === true ? 'HEAD' : onlyChangedParam;
   const untrackedFiles = childProcess.execSync('git ls-files --others --exclude-standard', { encoding: 'utf-8' }).split('\n').filter(Boolean);
-  const changedFiles = childProcess.execSync('git diff --name-only', { encoding: 'utf-8' }).split('\n').filter(Boolean);
+  const changedFiles = childProcess.execSync(`git diff ${baseCommit} --name-only`, { encoding: 'utf-8' }).split('\n').filter(Boolean);
 
   return [...untrackedFiles, ...changedFiles];
 }
 
-export async function createFileFiltersFromArguments(args: string[], onlyChanged: boolean): Promise<TestFileFilter[]> {
+export async function createFileFiltersFromArguments(args: string[], onlyChanged: string | boolean | undefined): Promise<TestFileFilter[]> {
   if (onlyChanged)
-    args = await detectChangedFiles();
+    args = await detectChangedFiles(onlyChanged);
 
   return args.map(arg => {
     const match = /^(.*?):(\d+):?(\d+)?$/.exec(arg);
@@ -101,7 +102,7 @@ export async function createFileFiltersFromArguments(args: string[], onlyChanged
   });
 }
 
-export async function createFileMatcherFromArguments(args: string[], onlyChanged: boolean): Promise<Matcher> {
+export async function createFileMatcherFromArguments(args: string[], onlyChanged: string | undefined): Promise<Matcher> {
   const filters = await createFileFiltersFromArguments(args, onlyChanged);
   return createFileMatcher(filters.map(filter => filter.re || filter.exact || ''));
 }
diff --git a/tests/playwright-test/only-changed.spec.ts b/tests/playwright-test/only-changed.spec.ts
index 86a71abf11..9c4f911129 100644
--- a/tests/playwright-test/only-changed.spec.ts
+++ b/tests/playwright-test/only-changed.spec.ts
@@ -74,3 +74,32 @@ test('should detect changed files', async ({ runInlineTest }) => {
   expect(result.output).toContain('b.spec.ts');
 });
 
+test('should diff based on base commit', 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); });
+      `);
+
+      execSync(`git commit -a -m update`, { cwd: baseDir });
+    }
+  }, { 'only-changed': `HEAD~1` });
+
+  expect(result.exitCode).toBe(1);
+  expect(result.failed).toBe(1);
+  expect(result.output).toContain('b.spec.ts');
+});
+