feat(@angular/build): add headless mode for vitest browser mode

Author: teoeter

packages/angular/build/src/builders/unit-test/builder.ts

@@ -333,6 +333,15 @@ function findBrowserProvider(
  }
 }
 
+function normalizeBrowserName(browserName: string): string {
+ // Normalize browser names to match Vitest's expectations for headless but also supports karma's names
+ // e.g., 'ChromeHeadless' -> 'chrome', 'FirefoxHeadless'
+ // and 'Chrome' -> 'chrome', 'Firefox' -> 'firefox'.
+ const normalized = browserName.toLowerCase();
+
+ return normalized.replace(/headless$/, '');
+}
+
 function setupBrowserConfiguration(
  browsers: string[] | undefined,
  debug: boolean,
@@ -380,8 +389,10 @@ function setupBrowserConfiguration(
  const browser = {
  enabled: true,
  provider,
+ headless: browsers.some((name) => name.toLowerCase().includes('headless')),
+
  instances: browsers.map((browserName) => ({
- browser: browserName,
+ browser: normalizeBrowserName(browserName),
  })),
  };
 

packages/angular/build/src/builders/unit-test/schema.json

@@ -19,7 +19,7 @@
  "enum": ["karma", "vitest"]
  },
  "browsers": {
- "description": "A list of browsers to use for test execution. If undefined, jsdom on Node.js will be used instead of a browser.",
+ "description": "A list of browsers to use for test execution. If undefined, jsdom on Node.js will be used instead of a browser. For Vitest and Karma, browser names ending with 'Headless' (e.g., 'ChromeHeadless') will enable headless mode for that browser.",
  "type": "array",
  "items": {
  "type": "string"