diff --git a/core/modules/file/lib/Drupal/file/Tests/FileManagedTestBase.php b/core/modules/file/lib/Drupal/file/Tests/FileManagedTestBase.php
index 616a829..b4c70c3 100644
--- a/core/modules/file/lib/Drupal/file/Tests/FileManagedTestBase.php
+++ b/core/modules/file/lib/Drupal/file/Tests/FileManagedTestBase.php
@@ -90,8 +90,7 @@ function assertFileHookCalled($hook, $expected_count = 1, $message = NULL) {
   }
 
   /**
-   * Check that two files have the same values for all fields other than the
-   * timestamp.
+   * Asserts that two files have the same values (except timestamp).
    *
    * @param \Drupal\file\FileInterface $before
    *   File object to compare.
@@ -109,7 +108,7 @@ function assertFileUnchanged(FileInterface $before, FileInterface $after) {
   }
 
   /**
-   * Check that two files are not the same by comparing the fid and filepath.
+   * Asserts that two files are not the same by comparing the fid and filepath.
    *
    * @param \Drupal\file\FileInterface $file1
    *   File object to compare.
@@ -122,7 +121,7 @@ function assertDifferentFile(FileInterface $file1, FileInterface $file2) {
   }
 
   /**
-   * Check that two files are the same by comparing the fid and filepath.
+   * Asserts that two files are the same by comparing the fid and filepath.
    *
    * @param \Drupal\file\FileInterface $file1
    *   File object to compare.
@@ -168,18 +167,19 @@ function createFile($filepath = NULL, $contents = NULL, $scheme = NULL) {
   }
 
   /**
-   * Create a file and return the URI of it.
+   * Creates a file and returns its URI.
    *
-   * @param $filepath
+   * @param string $filepath
    *   Optional string specifying the file path. If none is provided then a
    *   randomly named file will be created in the site's files directory.
-   * @param $contents
+   * @param string $contents
    *   Optional contents to save into the file. If a NULL value is provided an
    *   arbitrary string will be used.
-   * @param $scheme
+   * @param string $scheme
    *   Optional string indicating the stream scheme to use. Drupal core includes
    *   public, private, and temporary. The public wrapper is the default.
-   * @return
+   *
+   * @return string
    *   File URI.
    */
   function createUri($filepath = NULL, $contents = NULL, $scheme = NULL) {
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
index 18b3ae8..f4738fa 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
@@ -70,7 +70,7 @@
    *
    * @var array
    */
-  private $stream_wrappers = array();
+  private $streamWrappers = array();
 
   /**
    * Overrides \Drupal\simpletest\UnitTestBase::__construct().
@@ -159,7 +159,7 @@ protected function tearDown() {
     // of this test leaks into the parent environment. Unlike all other global
     // state variables in Drupal, stream wrappers are a global state construct
     // of PHP core, which has to be maintained manually.
-    foreach ($this->stream_wrappers as $scheme) {
+    foreach ($this->streamWrappers as $scheme) {
       $this->unregisterStreamWrapper($scheme);
     }
     parent::tearDown();
@@ -374,10 +374,10 @@ protected function disableModules(array $modules) {
    *   STREAM_WRAPPERS_LOCAL_NORMAL.
    */
   protected function registerStreamWrapper($scheme, $class, $type = STREAM_WRAPPERS_LOCAL_NORMAL) {
-    if (isset($this->stream_wrappers[$scheme])) {
+    if (isset($this->streamWrappers[$scheme])) {
       $this->unregisterStreamWrapper($scheme);
     }
-    $this->stream_wrappers[$scheme] = $scheme;
+    $this->streamWrappers[$scheme] = $scheme;
     if (($type & STREAM_WRAPPERS_LOCAL) == STREAM_WRAPPERS_LOCAL) {
       stream_wrapper_register($scheme, $class);
     }
@@ -404,7 +404,7 @@ protected function registerStreamWrapper($scheme, $class, $type = STREAM_WRAPPER
    */
   protected function unregisterStreamWrapper($scheme) {
     stream_wrapper_unregister($scheme);
-    unset($this->stream_wrappers[$scheme]);
+    unset($this->streamWrappers[$scheme]);
     // @todo Revamp Drupal's stream wrapper API for D8.
     $wrappers = &drupal_static('file_get_stream_wrappers');
     unset($wrappers[$scheme]);
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
index 3bb6e3f..dbf8440 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -968,7 +968,7 @@ protected function prepareEnvironment() {
     // - UnitTestBase operates in a completely empty environment.
     // - DrupalUnitTestBase supports and maintains stream wrappers in a custom
     //   way.
-    // - WebTestBase re-initializes Drupal stream wrappers are installation.
+    // - WebTestBase re-initializes Drupal stream wrappers after installation.
     // The original stream wrappers are restored after the test run.
     // @see TestBase::tearDown()
     $wrappers = file_get_stream_wrappers();