diff -u b/core/modules/user/tests/src/Functional/UserAdminLanguageTest.php b/core/modules/user/tests/src/Functional/UserAdminLanguageTest.php
--- b/core/modules/user/tests/src/Functional/UserAdminLanguageTest.php
+++ b/core/modules/user/tests/src/Functional/UserAdminLanguageTest.php
@@ -50,7 +50,7 @@
     $path = 'user/' . $this->adminUser->id() . '/edit';
     $this->drupalGet($path);
     // Ensure administration pages language settings widget is not available.
-    self::assertFalse($this->getSession()->getPage()->findField('edit-preferred-admin-langcode'));
+    $this->assertFalse($this->getSession()->getPage()->findField('edit-preferred-admin-langcode'));
   }
 
   /**
@@ -64,13 +64,13 @@
     // Checks with user administration pages language negotiation disabled.
     $this->drupalGet($path);
     // Ensure administration pages language settings widget is not available.
-    self::assertFalse($this->getSession()->getPage()->findField( 'edit-preferred-admin-langcode'));
+    $this->assertFalse($this->getSession()->getPage()->findField('edit-preferred-admin-langcode'));
 
     // Checks with user administration pages language negotiation enabled.
     $this->setLanguageNegotiation();
     $this->drupalGet($path);
     // Ensure administration pages language settings widget is available.
-    self::assertTrue($this->getSession()->getPage()->findField( 'edit-preferred-admin-langcode'));
+    $this->assertTrue($this->getSession()->getPage()->findField('edit-preferred-admin-langcode'));
   }
 
   /**
@@ -91,13 +91,13 @@
     $path = 'user/' . $this->adminUser->id() . '/edit';
     $this->drupalGet($path);
     // Ensure administration pages language setting is visible for admin.
-    self::assertTrue($this->getSession()->getPage()->findField( 'edit-preferred-admin-langcode'));
+    $this->assertTrue($this->getSession()->getPage()->findField( 'edit-preferred-admin-langcode'));
 
     // Ensure administration pages language setting is hidden for non-admins.
     $this->drupalLogin($this->regularUser);
     $path = 'user/' . $this->regularUser->id() . '/edit';
     $this->drupalGet($path);
-    self::assertFalse($this->getSession()->getPage()->findField('edit-preferred-admin-langcode'));
+    $this->assertFalse($this->getSession()->getPage()->findField('edit-preferred-admin-langcode'));
   }
 
   /**
diff -u b/core/modules/user/tests/src/Functional/UserCreateTest.php b/core/modules/user/tests/src/Functional/UserCreateTest.php
--- b/core/modules/user/tests/src/Functional/UserCreateTest.php
+++ b/core/modules/user/tests/src/Functional/UserCreateTest.php
@@ -33,8 +33,8 @@
     $user = $this->drupalCreateUser(['administer users']);
     $this->drupalLogin($user);
 
-    self::assertEquals($user->getCreatedTime(), REQUEST_TIME, 'Creating a user sets default "created" timestamp.');
-    self::assertEquals($user->getChangedTime(), REQUEST_TIME, 'Creating a user sets default "changed" timestamp.');
+    $this->assertEquals($user->getCreatedTime(), REQUEST_TIME, 'Creating a user sets default "created" timestamp.');
+    $this->assertEquals($user->getChangedTime(), REQUEST_TIME, 'Creating a user sets default "changed" timestamp.');
 
     // Create a field.
     $field_name = 'test_field';
@@ -73,7 +73,7 @@
     $this->drupalGet('admin/people/create');
     $web_assert->fieldValueEquals('edit-status-0', 0);
     $web_assert->fieldValueEquals('edit-status-1', 1);
-    self::assertTrue($this->xpath('//input[@type="radio" and @id="edit-status-1" and @checked="checked"]'),  'Default setting for user status is active.');
+    $this->assertTrue($this->xpath('//input[@type="radio" and @id="edit-status-1" and @checked="checked"]'),  'Default setting for user status is active.');
 
     // Test that browser autocomplete behavior does not occur.
     $web_assert->responseNotContains('data-user-info-from-browser');
@@ -104,17 +104,17 @@
 
       if ($notify) {
         $web_assert->pageTextContains(t('A welcome message with further instructions has been emailed to the new user @name.', ['@name' => $edit['name']]));
-        self::assertEquals(count($this->drupalGetMails()), 1, 'Notification email sent');
+        $this->assertEquals(count($this->drupalGetMails()), 1, 'Notification email sent');
       }
       else {
         $web_assert->pageTextContains(t('Created a new user account for @name. No email has been sent.', ['@name' => $edit['name']]));
-        self::assertEquals(count($this->drupalGetMails()), 0, 'Notification email not sent');
+        $this->assertEquals(count($this->drupalGetMails()), 0, 'Notification email not sent');
       }
 
       $this->drupalGet('admin/people');
       $web_assert->pageTextContains($edit['name']);
       $user = user_load_by_name($name);
-      self::assertEquals($user->isActive(), 'User is not blocked');
+      $this->assertEquals($user->isActive(), 'User is not blocked');
     }
 
     // Test that the password '0' is considered a password.
diff -u b/core/modules/user/tests/src/Functional/UserPasswordResetTest.php b/core/modules/user/tests/src/Functional/UserPasswordResetTest.php
--- b/core/modules/user/tests/src/Functional/UserPasswordResetTest.php
+++ b/core/modules/user/tests/src/Functional/UserPasswordResetTest.php
@@ -63,7 +63,7 @@
     $this->drupalLogin($account);
 
     $this->account = User::load($account->id());
-    $this->account->pass_raw = $account->pass_raw;
+    $this->account->passRaw = $account->pass_raw;
     $this->drupalLogout();
 
     // Set the last login time that is used to generate the one-time link so
@@ -92,7 +92,7 @@
     $this->drupalPostForm(NULL, $edit, t('Submit'));
 
     $web_assert->pageTextContains(t('@name is not recognized as a username or an email address.', ['@name' => $edit['name']]));
-    self::assertEquals(count($this->drupalGetMails(['id' => 'user_password_reset'])),0,'No email was sent when requesting a password for an invalid account.');
+    $this->assertEquals(count($this->drupalGetMails(['id' => 'user_password_reset'])),0,'No email was sent when requesting a password for an invalid account.');
 
     // Reset the password by username via the password reset page.
     $edit['name'] = $this->account->getDisplayName();
@@ -108,11 +108,11 @@
     // Ensure that the current url does not contain the hash and timestamp.
     $this->assertUrl(Url::fromRoute('user.reset.form', ['uid' => $this->account->id()]));
 
-    self::assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Ensure the password reset URL is not cached.
     $this->drupalGet($resetURL);
-    self::assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Check the one-time login page.
     $web_assert->pageTextContains($this->account->getDisplayName());
@@ -154,7 +154,7 @@
     $before = count($this->drupalGetMails(['id' => 'user_password_reset']));
     $edit = ['name' => $this->account->getEmail()];
     $this->drupalPostForm(NULL, $edit, t('Submit'));
-    self::assertTrue( count($this->drupalGetMails(['id' => 'user_password_reset'])) === $before + 1, 'Email sent when requesting password reset using email address.');
+    $this->assertTrue( count($this->drupalGetMails(['id' => 'user_password_reset'])) === $before + 1, 'Email sent when requesting password reset using email address.');
 
     // Visit the user edit page without pass-reset-token and make sure it does
     // not cause an error.
@@ -187,7 +187,7 @@
     $edit = ['name' => $blocked_account->getUsername()];
     $this->drupalPostForm(NULL, $edit, t('Submit'));
     $web_assert->responseContains(t('%name is blocked or has not been activated yet.', ['%name' => $blocked_account->getUsername()]));
-    self::assertTrue(count($this->drupalGetMails(['id' => 'user_password_reset'])) === $before, 'No email was sent when requesting password reset for a blocked account');
+    $this->assertTrue(count($this->drupalGetMails(['id' => 'user_password_reset'])) === $before, 'No email was sent when requesting password reset for a blocked account');
 
     // Verify a password reset link is invalidated when the user's email address changes.
     $this->drupalGet('user/password');
@@ -252,8 +252,10 @@
     // Log in as a different user.
     $this->drupalLogin($this->account);
     $this->drupalGet($resetURL);
-    $web_assert->responseContains('You have tried to use a one-time login link that has either been used or is no longer valid. Please request a new one using the form below.');
-
+    $this->assertRaw(new FormattableMarkup(
+      'Another user (%other_user) is already logged into the site on this computer, but you tried to use a one-time link for user %resetting_user. Please <a href=":logout">log out</a> and try using the link again.',
+      ['%other_user' => $this->account->getUsername(), '%resetting_user' => $another_account->getUsername(), ':logout' => Url::fromRoute('user.logout')->toString()]
+    ));
     $another_account->delete();
     $this->drupalGet($resetURL);
     $web_assert->pageTextContains('The one-time login link you clicked is invalid.');
diff -u b/core/modules/user/tests/src/Functional/UserRegistrationTest.php b/core/modules/user/tests/src/Functional/UserRegistrationTest.php
--- b/core/modules/user/tests/src/Functional/UserRegistrationTest.php
+++ b/core/modules/user/tests/src/Functional/UserRegistrationTest.php
@@ -45,7 +45,7 @@
     $storage = $this->container->get('entity_type.manager')->getStorage('user');
     $accounts = $storage->loadByProperties(['name' => $name, 'mail' => $mail]);
     $new_user = reset($accounts);
-    self::assertTrue($new_user->isActive(), 'New account is active after registration.');
+    $this->assertTrue($new_user->isActive(), 'New account is active after registration.');
     $resetURL = user_pass_reset_url($new_user);
     $this->drupalGet($resetURL);
     $web_assert->titleEquals('Set password | Drupal');
@@ -59,7 +59,7 @@
     $this->container->get('entity.manager')->getStorage('user')->resetCache();
     $accounts = $storage->loadByProperties(['name' => $name, 'mail' => $mail]);
     $new_user = reset($accounts);
-    self::assertFalse($new_user->isActive(), 'New account is blocked until approved by an administrator.');
+    $this->assertFalse($new_user->isActive(), 'New account is blocked until approved by an administrator.');
   }
 
   public function testRegistrationWithoutEmailVerification() {
@@ -212,7 +212,7 @@
 
     $user_storage = \Drupal::entityManager()->getStorage('user');
 
-    self::assertTrue($user_storage->loadByProperties(['name' => $edit['name']]));
+    $this->assertTrue($user_storage->loadByProperties(['name' => $edit['name']]));
     $this->drupalLogout();
 
     // Create a second account.
@@ -223,7 +223,7 @@
     $this->drupalPostForm('user/register', $edit, t('Create new account'));
     $web_assert->statusCodeEquals(200);
 
-    self::assertTrue($user_storage->loadByProperties(['name' => $edit['name']]));
+    $this->assertTrue($user_storage->loadByProperties(['name' => $edit['name']]));
   }
 
   public function testRegistrationDefaultValues() {
@@ -255,14 +255,14 @@
     $accounts = $this->container->get('entity_type.manager')->getStorage('user')
       ->loadByProperties(['name' => $name, 'mail' => $mail]);
     $new_user = reset($accounts);
-    self::assertEquals($new_user->getUsername(), $name, 'Username matches.');
-    self::assertEquals($new_user->getEmail(), $mail, 'Email address matches.');
-    self::assertTrue(($new_user->getCreatedTime() > REQUEST_TIME - 20 ), 'Correct creation time.');
-    self::assertEquals($new_user->isActive(), $config_user_settings->get('register') == USER_REGISTER_VISITORS ? 1 : 0, 'Correct status field.');
-    self::assertEquals($new_user->getTimezone(), $config_system_date->get('timezone.default'), 'Correct time zone field.');
-    self::assertEquals($new_user->langcode->value, \Drupal::languageManager()->getDefaultLanguage()->getId(), 'Correct language field.');
-    self::assertEquals($new_user->preferred_langcode->value, \Drupal::languageManager()->getDefaultLanguage()->getId(), 'Correct preferred language field.');
-    self::assertEquals($new_user->init->value, $mail, 'Correct init field.');
+    $this->assertEquals($new_user->getUsername(), $name, 'Username matches.');
+    $this->assertEquals($new_user->getEmail(), $mail, 'Email address matches.');
+    $this->assertTrue(($new_user->getCreatedTime() > REQUEST_TIME - 20 ), 'Correct creation time.');
+    $this->assertEquals($new_user->isActive(), $config_user_settings->get('register') == USER_REGISTER_VISITORS ? 1 : 0, 'Correct status field.');
+    $this->assertEquals($new_user->getTimezone(), $config_system_date->get('timezone.default'), 'Correct time zone field.');
+    $this->assertEquals($new_user->langcode->value, \Drupal::languageManager()->getDefaultLanguage()->getId(), 'Correct language field.');
+    $this->assertEquals($new_user->preferred_langcode->value, \Drupal::languageManager()->getDefaultLanguage()->getId(), 'Correct preferred language field.');
+    $this->assertEquals($new_user->init->value, $mail, 'Correct init field.');
   }
 
   /**
@@ -347,7 +347,7 @@
     $accounts = $this->container->get('entity_type.manager')->getStorage('user')
       ->loadByProperties(['name' => $name, 'mail' => $mail]);
     $new_user = reset($accounts);
-    self::assertEquals($new_user->test_user_field->value, $value, 'The field value was correctly saved.');
+    $this->assertEquals($new_user->test_user_field->value, $value, 'The field value was correctly saved.');
 
     // Check that the 'add more' button works.
     $field_storage->setCardinality(FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED);
@@ -370,9 +370,9 @@
     $accounts = $this->container->get('entity_type.manager')->getStorage('user')
       ->loadByProperties(['name' => $name, 'mail' => $mail]);
     $new_user = reset($accounts);
-    self::assertEquals($new_user->test_user_field[0]->value, $value, t('The field value was correctly saved.'));
-    self::assertEquals($new_user->test_user_field[1]->value, $value + 1, t('The field value was correctly saved.'));
-    self::assertEquals($new_user->test_user_field[2]->value, $value + 2, t('The field value was correctly saved.'));
+    $this->assertEquals($new_user->test_user_field[0]->value, $value, t('The field value was correctly saved.'));
+    $this->assertEquals($new_user->test_user_field[1]->value, $value + 1, t('The field value was correctly saved.'));
+    $this->assertEquals($new_user->test_user_field[2]->value, $value + 2, t('The field value was correctly saved.'));
   }
 
   /**