Issue #1894692 by sun: allow to identify whether a user is logged using an API

core/modules/simpletest/lib/Drupal/simpletest/Tests/UserHelpersTest.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\simpletest\Tests\UserLoginTest.
+ */
+
+namespace Drupal\simpletest\Tests;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests User related helper methods of WebTestBase.
+ */
+class UserHelpersTest extends WebTestBase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'User helper methods',
+      'description' => 'Tests User related helper methods of WebTestBase.',
+      'group' => 'SimpleTest',
+    );
+  }
+
+  /**
+   * Tests WebTestBase::drupalUserIsLoggedIn().
+   */
+  function testDrupalUserIsLoggedIn() {
+    $first_user = $this->drupalCreateUser();
+    $second_user = $this->drupalCreateUser();
+
+    // After logging in, the first user should be logged in, the second not.
+    $this->drupalLogin($first_user);
+    $this->assertTrue($this->drupalUserIsLoggedIn($first_user));
+    $this->assertFalse($this->drupalUserIsLoggedIn($second_user));
+
+    // Verify that logged in state is retained across pages.
+    $this->drupalGet('');
+    $this->assertTrue($this->drupalUserIsLoggedIn($first_user));
+    $this->assertFalse($this->drupalUserIsLoggedIn($second_user));
+
+    // After logging out, both users should be logged out.
+    $this->drupalLogout();
+    $this->assertFalse($this->drupalUserIsLoggedIn($first_user));
+    $this->assertFalse($this->drupalUserIsLoggedIn($second_user));
+
+    // After logging back in, the second user should still be logged out.
+    $this->drupalLogin($first_user);
+    $this->assertTrue($this->drupalUserIsLoggedIn($first_user));
+    $this->assertFalse($this->drupalUserIsLoggedIn($second_user));
+
+    // After logging in the second user, the first one should be logged out.
+    $this->drupalLogin($second_user);
+    $this->assertTrue($this->drupalUserIsLoggedIn($second_user));
+    $this->assertFalse($this->drupalUserIsLoggedIn($first_user));
+
+    // After logging out, both should be logged out.
+    $this->drupalLogout();
+    $this->assertFalse($this->drupalUserIsLoggedIn($first_user));
+    $this->assertFalse($this->drupalUserIsLoggedIn($second_user));
+  }
+
+}

core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php

@@ -632,15 +632,30 @@ protected function drupalLogin($user) {
     );
     $this->drupalPost('user', $edit, t('Log in'));
 
-    // If a "log out" link appears on the page, it is almost certainly because
-    // the login was successful.
-    $pass = $this->assertLink(t('Log out'), 0, t('User %name successfully logged in.', array('%name' => $user->name)), t('User login'));
-
+    // @see WebTestBase::drupalUserIsLoggedIn()
+    if (isset($this->session_id)) {
+      $user->session_id = $this->session_id;
+    }
+    $pass = $this->assert($this->drupalUserIsLoggedIn($user), format_string('User %name successfully logged in.', array('%name' => $user->name)), 'User login');
     if ($pass) {
       $this->loggedInUser = $user;
     }
   }
 
+  /**
+   * Returns whether a given user account is logged in.
+   *
+   * @param \Drupal\user\User $account
+   *   The user account object to check.
+   */
+  protected function drupalUserIsLoggedIn($account) {
+    if (!isset($account->session_id)) {
+      return FALSE;
+    }
+    // @see _drupal_session_read()
+    return (bool) db_query("SELECT sid FROM {users} u INNER JOIN {sessions} s ON u.uid = s.uid WHERE s.sid = :sid", array(':sid' => $account->session_id))->fetchField();
+  }
+
   /**
    * Generate a token for the currently logged in user.
    */
@@ -662,6 +677,8 @@ protected function drupalLogout() {
     $pass = $pass && $this->assertField('pass', t('Password field found.'), t('Logout'));
 
     if ($pass) {
+      // @see WebTestBase::drupalUserIsLoggedIn()
+      unset($this->loggedInUser->session_id);
       $this->loggedInUser = FALSE;
     }
   }