Testing: Assign E2E login credentials explicitly

packages/e2e-test-utils/src/login-user.js

@@ -1,11 +1,9 @@
-
 /**
  * Internal dependencies
  */
 import { WP_USERNAME, WP_PASSWORD } from './shared/config';
 import { createURL } from './create-url';
 import { isCurrentURL } from './is-current-url';
-import { pressKeyWithModifier } from './press-key-with-modifier';
 
 /**
  * Performs log in with specified username and password.
@@ -20,12 +18,16 @@ export async function loginUser( username = WP_USERNAME, password = WP_PASSWORD
 		);
 	}
 
-	await page.focus( '#user_login' );
-	await pressKeyWithModifier( 'primary', 'a' );
-	await page.type( '#user_login', username );
-	await page.focus( '#user_pass' );
-	await pressKeyWithModifier( 'primary', 'a' );
-	await page.type( '#user_pass', password );
+	// Explicitly assign values of form, since the username is prefilled if
+	// already logged in. This could be done by keyboard interactions as well,
+	// but as of Puppeteer 1.6.1, Cmd+A does not work as expected in Mac,
+	// making it difficult to erase the contents of the field.
+	//
+	// See: https://github.com/GoogleChrome/puppeteer/issues/1313
+	await page.evaluate( ( _username, _password ) => {
+		document.getElementById( 'user_login' ).value = _username;
+		document.getElementById( 'user_pass' ).value = _password;
+	}, username, password );
 
 	await Promise.all( [ page.waitForNavigation(), page.click( '#wp-submit' ) ] );
 }