diff --git a/core/modules/simpletest/lib/Drupal/simpletest/Tests/BrowserTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/BrowserTest.php
index fadc99a290ca3073169609f3133e246ca88349e4..0e27818cbd1424740b69a74a04061aefc0d92aa9 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/Tests/BrowserTest.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/BrowserTest.php
@@ -29,18 +29,18 @@ function testGetAbsoluteUrl() {
 
     $this->drupalGet($url);
     $absolute = url($url, array('absolute' => TRUE));
-    $this->assertEqual($absolute, $this->url, t('Passed and requested URL are equal.'));
-    $this->assertEqual($this->url, $this->getAbsoluteUrl($this->url), t('Requested and returned absolute URL are equal.'));
+    $this->assertEqual($absolute, $this->url, 'Passed and requested URL are equal.');
+    $this->assertEqual($this->url, $this->getAbsoluteUrl($this->url), 'Requested and returned absolute URL are equal.');
 
     $this->drupalPost(NULL, array(), t('Log in'));
-    $this->assertEqual($absolute, $this->url, t('Passed and requested URL are equal.'));
-    $this->assertEqual($this->url, $this->getAbsoluteUrl($this->url), t('Requested and returned absolute URL are equal.'));
+    $this->assertEqual($absolute, $this->url, 'Passed and requested URL are equal.');
+    $this->assertEqual($this->url, $this->getAbsoluteUrl($this->url), 'Requested and returned absolute URL are equal.');
 
     $this->clickLink('Create new account');
     $url = 'user/register';
     $absolute = url($url, array('absolute' => TRUE));
-    $this->assertEqual($absolute, $this->url, t('Passed and requested URL are equal.'));
-    $this->assertEqual($this->url, $this->getAbsoluteUrl($this->url), t('Requested and returned absolute URL are equal.'));
+    $this->assertEqual($absolute, $this->url, 'Passed and requested URL are equal.');
+    $this->assertEqual($this->url, $this->getAbsoluteUrl($this->url), 'Requested and returned absolute URL are equal.');
   }
 
   /**
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/Tests/FolderTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/FolderTest.php
index f49868b0e3fe9916c59f61625af702ebbb9b4046..fa9db2ecd7af89a3735e583cd78c2dd81a19aa91 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/Tests/FolderTest.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/FolderTest.php
@@ -31,6 +31,6 @@ public static function getInfo() {
 
   function testFolderSetup() {
     $directory = file_default_scheme() . '://styles';
-    $this->assertTrue(file_prepare_directory($directory, FALSE), "Directory created.");
+    $this->assertTrue(file_prepare_directory($directory, FALSE), 'Directory created.');
   }
 }
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/Tests/MailCaptureTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/MailCaptureTest.php
index da0fb5db03b4da4779556264fd20b3e8fb45e309..95481d1d9992d7a0140f027778f53c1161f8ced1 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/Tests/MailCaptureTest.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/MailCaptureTest.php
@@ -38,19 +38,19 @@ function testMailSend() {
 
     // Before we send the e-mail, drupalGetMails should return an empty array.
     $captured_emails = $this->drupalGetMails();
-    $this->assertEqual(count($captured_emails), 0, t('The captured e-mails queue is empty.'), t('E-mail'));
+    $this->assertEqual(count($captured_emails), 0, 'The captured e-mails queue is empty.', 'E-mail');
 
     // Send the e-mail.
     $response = drupal_mail_system('simpletest', 'drupal_mail_test')->mail($message);
 
     // Ensure that there is one e-mail in the captured e-mails array.
     $captured_emails = $this->drupalGetMails();
-    $this->assertEqual(count($captured_emails), 1, t('One e-mail was captured.'), t('E-mail'));
+    $this->assertEqual(count($captured_emails), 1, 'One e-mail was captured.', 'E-mail');
 
     // Assert that the e-mail was sent by iterating over the message properties
     // and ensuring that they are captured intact.
     foreach ($message as $field => $value) {
-      $this->assertMail($field, $value, t('The e-mail was sent and the value for property @field is intact.', array('@field' => $field)), t('E-mail'));
+      $this->assertMail($field, $value, format_string('The e-mail was sent and the value for property @field is intact.', array('@field' => $field)), 'E-mail');
     }
 
     // Send additional e-mails so more than one e-mail is captured.
@@ -67,20 +67,20 @@ function testMailSend() {
 
     // There should now be 6 e-mails captured.
     $captured_emails = $this->drupalGetMails();
-    $this->assertEqual(count($captured_emails), 6, t('All e-mails were captured.'), t('E-mail'));
+    $this->assertEqual(count($captured_emails), 6, 'All e-mails were captured.', 'E-mail');
 
     // Test different ways of getting filtered e-mails via drupalGetMails().
     $captured_emails = $this->drupalGetMails(array('id' => 'drupal_mail_test'));
-    $this->assertEqual(count($captured_emails), 1, t('Only one e-mail is returned when filtering by id.'), t('E-mail'));
+    $this->assertEqual(count($captured_emails), 1, 'Only one e-mail is returned when filtering by id.', 'E-mail');
     $captured_emails = $this->drupalGetMails(array('id' => 'drupal_mail_test', 'subject' => $subject));
-    $this->assertEqual(count($captured_emails), 1, t('Only one e-mail is returned when filtering by id and subject.'), t('E-mail'));
+    $this->assertEqual(count($captured_emails), 1, 'Only one e-mail is returned when filtering by id and subject.', 'E-mail');
     $captured_emails = $this->drupalGetMails(array('id' => 'drupal_mail_test', 'subject' => $subject, 'from' => 'this_was_not_used@example.com'));
-    $this->assertEqual(count($captured_emails), 0, t('No e-mails are returned when querying with an unused from address.'), t('E-mail'));
+    $this->assertEqual(count($captured_emails), 0, 'No e-mails are returned when querying with an unused from address.', 'E-mail');
 
     // Send the last e-mail again, so we can confirm that the drupalGetMails-filter
     // correctly returns all e-mails with a given property/value.
     drupal_mail_system('drupal_mail_test', $index)->mail($message);
     $captured_emails = $this->drupalGetMails(array('id' => 'drupal_mail_test_4'));
-    $this->assertEqual(count($captured_emails), 2, t('All e-mails with the same id are returned when filtering by id.'), t('E-mail'));
+    $this->assertEqual(count($captured_emails), 2, 'All e-mails with the same id are returned when filtering by id.', 'E-mail');
   }
 }
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
index 8db5bde2afb6669760db0876fa0ac658c22a4b1c..a4641f60672df3d7e802c90e6f4b58bbb89c8c07 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
@@ -58,7 +58,7 @@ function testInternalBrowser() {
     if (!$this->inCURL()) {
       // Retrieve the test page and check its title and headers.
       $this->drupalGet('test-page');
-      $this->assertTrue($this->drupalGetHeader('Date'), t('An HTTP header was received.'));
+      $this->assertTrue($this->drupalGetHeader('Date'), 'An HTTP header was received.');
       $this->assertTitle(t('Test page | @site-name', array(
         '@site-name' => config('system.site')->get('name'),
       )));
@@ -74,12 +74,12 @@ function testInternalBrowser() {
       $user = $this->drupalCreateUser();
       $this->drupalLogin($user);
       $headers = $this->drupalGetHeaders(TRUE);
-      $this->assertEqual(count($headers), 2, t('There was one intermediate request.'));
-      $this->assertTrue(strpos($headers[0][':status'], '302') !== FALSE, t('Intermediate response code was 302.'));
-      $this->assertFalse(empty($headers[0]['location']), t('Intermediate request contained a Location header.'));
-      $this->assertEqual($this->getUrl(), $headers[0]['location'], t('HTTP redirect was followed'));
-      $this->assertFalse($this->drupalGetHeader('Location'), t('Headers from intermediate request were reset.'));
-      $this->assertResponse(200, t('Response code from intermediate request was reset.'));
+      $this->assertEqual(count($headers), 2, 'There was one intermediate request.');
+      $this->assertTrue(strpos($headers[0][':status'], '302') !== FALSE, 'Intermediate response code was 302.');
+      $this->assertFalse(empty($headers[0]['location']), 'Intermediate request contained a Location header.');
+      $this->assertEqual($this->getUrl(), $headers[0]['location'], 'HTTP redirect was followed');
+      $this->assertFalse($this->drupalGetHeader('Location'), 'Headers from intermediate request were reset.');
+      $this->assertResponse(200, 'Response code from intermediate request was reset.');
 
       // Test the maximum redirection option.
       $this->drupalLogout();
@@ -92,7 +92,7 @@ function testInternalBrowser() {
         'query' => array('destination' => 'user/logout'),
       ));
       $headers = $this->drupalGetHeaders(TRUE);
-      $this->assertEqual(count($headers), 2, t('Simpletest stopped following redirects after the first one.'));
+      $this->assertEqual(count($headers), 2, 'Simpletest stopped following redirects after the first one.');
     }
   }
 
@@ -106,30 +106,30 @@ function testUserAgentValidation() {
       $HTTP_path = $system_path .'/tests/http.php?q=node';
       $https_path = $system_path .'/tests/https.php?q=node';
       // Generate a valid simpletest User-Agent to pass validation.
-      $this->assertTrue(preg_match('/simpletest\d+/', $this->databasePrefix, $matches), t('Database prefix contains simpletest prefix.'));
+      $this->assertTrue(preg_match('/simpletest\d+/', $this->databasePrefix, $matches), 'Database prefix contains simpletest prefix.');
       $test_ua = drupal_generate_test_ua($matches[0]);
       $this->additionalCurlOptions = array(CURLOPT_USERAGENT => $test_ua);
 
       // Test pages only available for testing.
       $this->drupalGet($HTTP_path);
-      $this->assertResponse(200, t('Requesting http.php with a legitimate simpletest User-Agent returns OK.'));
+      $this->assertResponse(200, 'Requesting http.php with a legitimate simpletest User-Agent returns OK.');
       $this->drupalGet($https_path);
-      $this->assertResponse(200, t('Requesting https.php with a legitimate simpletest User-Agent returns OK.'));
+      $this->assertResponse(200, 'Requesting https.php with a legitimate simpletest User-Agent returns OK.');
 
       // Now slightly modify the HMAC on the header, which should not validate.
       $this->additionalCurlOptions = array(CURLOPT_USERAGENT => $test_ua . 'X');
       $this->drupalGet($HTTP_path);
-      $this->assertResponse(403, t('Requesting http.php with a bad simpletest User-Agent fails.'));
+      $this->assertResponse(403, 'Requesting http.php with a bad simpletest User-Agent fails.');
       $this->drupalGet($https_path);
-      $this->assertResponse(403, t('Requesting https.php with a bad simpletest User-Agent fails.'));
+      $this->assertResponse(403, 'Requesting https.php with a bad simpletest User-Agent fails.');
 
       // Use a real User-Agent and verify that the special files http.php and
       // https.php can't be accessed.
       $this->additionalCurlOptions = array(CURLOPT_USERAGENT => 'Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.12) Gecko/20101026 Firefox/3.6.12');
       $this->drupalGet($HTTP_path);
-      $this->assertResponse(403, t('Requesting http.php with a normal User-Agent fails.'));
+      $this->assertResponse(403, 'Requesting http.php with a normal User-Agent fails.');
       $this->drupalGet($https_path);
-      $this->assertResponse(403, t('Requesting https.php with a normal User-Agent fails.'));
+      $this->assertResponse(403, 'Requesting https.php with a normal User-Agent fails.');
     }
   }
 
@@ -165,7 +165,7 @@ function testWebTestRunner() {
 
       // Regression test for #290316.
       // Check that test_id is incrementing.
-      $this->assertTrue($this->test_ids[0] != $this->test_ids[1], t('Test ID is incrementing.'));
+      $this->assertTrue($this->test_ids[0] != $this->test_ids[1], 'Test ID is incrementing.');
     }
   }
 
@@ -228,7 +228,7 @@ function confirmStubTestResults() {
     $this->assertEqual('6 passes, 5 fails, 2 exceptions, and 1 debug message', $this->childTestResults['summary'], 'Stub test summary is correct');
 
     $this->test_ids[] = $test_id = $this->getTestIdFromResults();
-    $this->assertTrue($test_id, t('Found test ID in results.'));
+    $this->assertTrue($test_id, 'Found test ID in results.');
   }
 
   /**
@@ -267,7 +267,7 @@ function assertAssertion($message, $type, $status, $file, $function) {
         break;
       }
     }
-    return $this->assertTrue($found, t('Found assertion {"@message", "@type", "@status", "@file", "@function"}.', array('@message' => $message, '@type' => $type, '@status' => $status, "@file" => $file, "@function" => $function)));
+    return $this->assertTrue($found, format_string('Found assertion {"@message", "@type", "@status", "@file", "@function"}.', array('@message' => $message, '@type' => $type, '@status' => $status, "@file" => $file, "@function" => $function)));
   }
 
   /**