Imported from codertjay/chromium (chrome/browser/web_applications/docs/skills/create-web-applications-browsertest/SKILL.md). Install upstream with npx skills add codertjay/chromium --skill create-web-applications-browsertest. Copyright stays with the author.

Creating Web Applications Browsertests

This skill guides the process of creating a browsertest in the chrome/browser/web_applications directory. Read the testing documentation for information about testing infrastructure in the WebAppProvider system.

1. Test Base Class & Setup

For simple tests that don't need extra setup or flags, simply use using MyWebAppBrowserTest = WebAppBrowserTestBase. If more complex fixture logic is needed, like holding a base::HistogramTester or enabling a feature flag, inherit from WebAppBrowserTestBase.

WebAppBrowserTestBase automatically ensures the WebAppProvider system is started correctly in the SetUpOnMainThread() method, OS integration features are 'faked' out using the OsIntegrationTestOverride system, and the embedded_https_test_server() is started. See the header file for more information about capabilities it provides.

2. Test Execution Environment Setup

In your test, use the embedded test server to serve URLs, and testing helpers from WebAppBrowserTestBase to set up initial state.

Browser tests usually cause commands to execute via the high level operations done by the user, like navigating the browser, interacting with a web app window or dialog, etc. Due to this, waiting methods outlined in the testing documentation are often essential to reliably wait for, say, commands to be scheduled, completed, and state updated etc.

IN_PROC_BROWSER_TEST_F(MyWebAppBrowserTest, InstallAndLaunch) {
  GURL app_url = embedded_https_test_server()->GetURL("/web_apps/simple/index.html");

  // 1. Setup Phase
  Browser* app_browser = InstallWebAppFromPageGetBrowser(browser(), app_url);

  // 2. Execution Phase
  // Example 1) Cause an update by navigating browser() to a (not yet created)
  // URL like "/web_apps/simple/update_theme_color.html" which links to a
  // manifest with a new theme color.
  //
  // Example 2) Interact with the toolbar of app_browser() to, say click the
  // uninstall button from the 3-dot menu.

  ...
}

3. Waiting & Stability

Browsertests run a real browser, so you must carefully wait for UI and network events to complete. Wait for commands in the WebAppProvider to settle if you've triggered background work.

// Wait for web content's manifest to make it to the WebAppTabHelper for
// operations like update:
test::WaitForLoadCompleteAndMaybeManifestSeen(
    browser()->tab_strip_model()->GetActiveWebContents());

// Wait for commands to finish.
provider().command_manager().AwaitAllCommandsCompleteForTesting();

// Potentially use observers if needed, etc.

4. Validating State

Tests can use internal state like provider().registrar_unsafe() or provider().icon_manager() to verify assumptions, but in general browser tests are intended to check 'user visible' / 'developer visible' / other end-to-end state, so checking the results via something like web contents state, browser state, ui state, and os integration state (via WebAppBrowserTestBase::os_integration_override()) is most appropriate.