test: disable parallelism

- avoid Musicbrainz rate limiting
- avoid race condition when creating test entities

Author: dvirtz

lib/test-support/src/test-config.ts

@@ -1,7 +1,7 @@
+import {UserscriptTestOptions} from '#userscript-test.ts';
 import {defineConfig as defineTestConfig, devices, type PlaywrightTestConfig} from '@playwright/test';
 import dotenv from 'dotenv';
 import path from 'path';
-import {UserscriptTestOptions} from '#userscript-test.ts';
 
 /**
  * Read environment variables from file.
@@ -14,14 +14,12 @@ dotenv.config({path: path.resolve(import.meta.dirname, '..', '..', '..', '.env')
  */
 export function defineConfig(baseURL: string, userscriptPath: string, options?: PlaywrightTestConfig) {
   return defineTestConfig<UserscriptTestOptions>({
-    /* Run tests in files in parallel */
-    fullyParallel: true,
     /* Fail the build on CI if you accidentally left test.only in the source code. */
     forbidOnly: !!process.env.CI,
     /* Retry on CI only */
     retries: process.env.CI ? 2 : 0,
-    /* Opt out of parallel tests on CI. */
-    workers: process.env.CI ? 1 : undefined,
+    /* Can't run in parallel due to Musicbrainz rate limit */
+    workers: 1,
     /* Reporter to use. See https://playwright.dev/docs/test-reporters */
     reporter: 'html',
     /* Shared settings for all the projects below. See https://playwright.dev/docs/api/class-testoptions. */