Chromium Docs

Chrome for Testing Differences

This document summarizes the functional and behavioral differences introduced when Chrome is built with the BUILDFLAG(CHROME_FOR_TESTING) and BUILDFLAG(GOOGLE_CHROME_FOR_TESTING_BRANDING) build flags. The latter enables Google Chrome for Testing specific branding. This affects application icons, installation paths (e.g., for native messaging hosts and enterprise policies), and enables proprietary media codecs (e.g., H.264, AAC, MP3). Without it Chrome for Testing acts like Chromium for Testing.

1. Configuration

Chrome for Testing can be configured by supplying a JSON configuration file using the --chrome-for-testing-config command line switch. Refer to docs/chrome_for_testing/chrome_for_testing_configuration.md for more details.

2. Startup & Configuration

  • Required Components Loading: Chrome for Testing (CfT) relies on a dedicated JSON configuration loaded during early browser initialization via chrome_for_testing::LoadConfig().
  • Startup Synchronization: It injects custom synchronization logic into ChromeBrowserMainParts. The browser explicitly blocks and delays regular startup until all “required components” specified in the CfT config are installed or updated to the current version.
  • Component Updates Policy: By default, automatic component updates are disabled (kComponentUpdatesEnabledByDefault is forced to false).

3. User Data Directory

Chrome for Testing stores its profile and browser state in a dedicated user data directory location different from standard Chrome user data directory location. This prevents test profiles from interfering with day-to-day browser data. Details regarding exact path locations for each platform can be found in docs/user_data_dir.md.

4. Enterprise Policies

Chrome for Testing stores enterprise policies in a location different from standard Chrome enterprise policies location. Details regarding lookup behavior and specifics are covered in docs/enterprise/policies.md.

5. User Interface & Infobars

  • InfoBar Management:
    • CfT shows a non removable “Chrome for Testing” informational banner near the top of browser windows.
    • Non interactive infobars (those not requiring user response) can be suppressed using the --disable-infobars command line switch.
  • User Education & Choice Screens:
    • Disables all User Education components and In-Product Help (IPH) prompts by default.
    • Disables the “Search Engine Choice” dialog workflow that mandates selecting a default search engine upon first launch.
    • Note: These behaviors can be explicitly restored via keys in the JSON configuration if desired.

6. Virtual Clipboard

Chrome for Testing supports an optional process-specific virtual clipboard which operates independently from the system clipboard. This isolation helps to keep test execution hermetic.

Note: Virtual clipboard needs to be explicitly enabled in the JSON configuration.

7. System Integration & Operating System Specifics

  • Default Browser Disallowance: Chrome for Testing rejects any attempt to register itself as the OS default web browser or scheme client. The GetDefaultWebClientSetPermission() method always returns SET_DEFAULT_NOT_ALLOWED.
  • macOS Automation Optimizations:
    • Suppresses the automatic “Install from Disk Image” (DMG) prompt that ordinarily occurs when running from a mounted volume.
    • Completely strips the CodeSignCloneManager functionality. This mechanism prepares seamless path migration for silent macOS updates, which is redundant and overhead for an automated testing executable.

8. DevTools & Debugging

  • Debug Information Persistence: Explicitly enables local stack traces and crash dumps even in Official branding builds, maintaining a better debugging experience that usually relies on developer-only builds.
  • DevTools Integration: Hardcodes internal states in ChromeContentBrowserClient to treat the session configuration as actively managed by a DevTools client and passes &isChromeForTesting=true upstream to the inspector frontend interface.

9. Direct Automated Behavior Switches

  • Sign-In Automation: Implements the --enterprise-signin-dialog-behavior-for-testing switch. This enables testing infrastructure to auto-answer and auto-approve enterprise profile creation dialogs (e.g., "accept-new-profile", "accept-link-data", or "cancel") without requiring physical UI interaction or Selenium/CDP scripts.

10. Pre-built Binaries

Pre-built Chrome for Testing binaries are available across all the supported desktop platforms and Chrome/Chromium channels. You can access them via the Chrome for Testing dashboard.