E2E Test Utils: Add getCurrentUser(), and use it for user switching

packages/e2e-test-utils/src/get-current-user.js

@@ -0,0 +1,16 @@
+/**
+ * Get the username of the user that's currently logged into WordPress (if any).
+ *
+ * @return {string?} username The user that's currently logged into WordPress (if any).
+ */
+export async function getCurrentUser() {
+	const cookies = await page.cookies();
+	const cookie = cookies.find(
+		( c ) => !! c?.name?.startsWith( 'wordpress_logged_in_' )
+	);
+
+	if ( ! cookie?.value ) {
+		return;
+	}
+	return decodeURIComponent( cookie.value ).split( '|' )[ 0 ];
+}

packages/e2e-test-utils/src/switch-user-to-admin.js

@@ -1,15 +1,16 @@
 /**
  * Internal dependencies
  */
+import { getCurrentUser } from './get-current-user';
 import { loginUser } from './login-user';
-import { WP_USERNAME, WP_ADMIN_USER } from './shared/config';
+import { WP_ADMIN_USER } from './shared/config';
 
 /**
  * Switches the current user to the admin user (if the user
  * running the test is not already the admin user).
  */
 export async function switchUserToAdmin() {
-	if ( WP_USERNAME === WP_ADMIN_USER.username ) {
+	if ( ( await getCurrentUser() ) === WP_ADMIN_USER.username ) {
 		return;
 	}
 	await loginUser( WP_ADMIN_USER.username, WP_ADMIN_USER.password );

packages/e2e-test-utils/src/switch-user-to-test.js

@@ -1,15 +1,16 @@
 /**
  * Internal dependencies
  */
+import { getCurrentUser } from './get-current-user';
 import { loginUser } from './login-user';
-import { WP_USERNAME, WP_ADMIN_USER } from './shared/config';
+import { WP_USERNAME } from './shared/config';
 
 /**
  * Switches the current user to whichever user we should be
  * running the tests as (if we're not already that user).
  */
 export async function switchUserToTest() {
-	if ( WP_USERNAME === WP_ADMIN_USER.username ) {
+	if ( ( await getCurrentUser() ) === WP_USERNAME ) {
 		return;
 	}
 	await loginUser();