diff --git a/core/modules/migrate/src/Tests/MigrateDumpAlterInterface.php b/core/modules/migrate/src/Tests/MigrateDumpAlterInterface.php
new file mode 100644
index 0000000..94b8a3d
--- /dev/null
+++ b/core/modules/migrate/src/Tests/MigrateDumpAlterInterface.php
@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\migrate\Tests\MigrateDumpAlterInterface.
+ */
+
+namespace Drupal\migrate\Tests;
+
+use Drupal\simpletest\TestBase;
+
+/**
+ * Allows tests to alter dumps after they've loaded.
+ *
+ * @s
+ * @see \Drupal\migrate_drupal\Tests\d6\MigrateFileTest
+ */
+interface MigrateDumpAlterInterface {
+
+  /**
+   * Allows tests to alter dumps after they've loaded.
+   *
+   * @param \Drupal\simpletest\TestBase $test
+   *   The test that is being run.
+   */
+  public static function migrateDumpAlter(TestBase $test);
+
+}
diff --git a/core/modules/migrate/src/Tests/MigrateTestBase.php b/core/modules/migrate/src/Tests/MigrateTestBase.php
index 764c49e..a4c154a 100644
--- a/core/modules/migrate/src/Tests/MigrateTestBase.php
+++ b/core/modules/migrate/src/Tests/MigrateTestBase.php
@@ -79,6 +79,9 @@ protected function tearDown() {
    */
   protected function prepare(MigrationInterface $migration, array $files = array()) {
     $this->loadDumps($files);
+    if ($this instanceof MigrateDumpAlterInterface) {
+      static::migrateDumpAlter($this);
+    }
   }
 
   /**
diff --git a/core/modules/migrate_drupal/src/Tests/MigrateFullDrupalTestBase.php b/core/modules/migrate_drupal/src/Tests/MigrateFullDrupalTestBase.php
index 956a4e6..09dd3cd 100644
--- a/core/modules/migrate_drupal/src/Tests/MigrateFullDrupalTestBase.php
+++ b/core/modules/migrate_drupal/src/Tests/MigrateFullDrupalTestBase.php
@@ -54,6 +54,11 @@ public function testDrupal() {
     $this->loadDumps($dumps);
 
     $classes = $this->getTestClassesList();
+    foreach ($classes as $class) {
+      if (is_subclass_of($class, '\Drupal\migrate\Tests\MigrateDumpAlterInterface')) {
+        $class::migrateDumpAlter($this);
+      }
+    }
 
     // Run every migration in the order specified by the storage controller.
     foreach (entity_load_multiple('migration', static::$migrations) as $migration) {
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateDrupal6Test.php b/core/modules/migrate_drupal/src/Tests/d6/MigrateDrupal6Test.php
index a644a99..33835a7 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateDrupal6Test.php
+++ b/core/modules/migrate_drupal/src/Tests/d6/MigrateDrupal6Test.php
@@ -158,9 +158,6 @@ protected function setUp() {
     $config->set('default', 'bartik');
     $config->set('admin', 'seven');
     $config->save();
-
-    // We need a temp file for testing the MigrateFileTest.
-    file_put_contents('/tmp/some-temp-file.jpg', '');
   }
 
   /**
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateFileTest.php b/core/modules/migrate_drupal/src/Tests/d6/MigrateFileTest.php
index 342c077..91560a4 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateFileTest.php
+++ b/core/modules/migrate_drupal/src/Tests/d6/MigrateFileTest.php
@@ -7,16 +7,26 @@
 
 namespace Drupal\migrate_drupal\Tests\d6;
 
+use Drupal\Component\Utility\Random;
 use Drupal\migrate\MigrateExecutable;
+use Drupal\migrate\Tests\MigrateDumpAlterInterface;
 use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
 use Drupal\Core\Database\Database;
+use Drupal\simpletest\TestBase;
 
 /**
  * file migration.
  *
  * @group migrate_drupal
  */
-class MigrateFileTest extends MigrateDrupal6TestBase {
+class MigrateFileTest extends MigrateDrupal6TestBase implements MigrateDumpAlterInterface {
+
+  /**
+   * The filename of a file used to test temporary file migration.
+   *
+   * @var string
+   */
+  protected static $tempFilename;
 
   /**
    * Modules to enable.
@@ -29,9 +39,6 @@ class MigrateFileTest extends MigrateDrupal6TestBase {
    * {@inheritdoc}
    */
   protected function setUp() {
-    // Set the temp file of the site to the same as the D6 site, this allows us
-    // to test files which start and finish in the same place.
-    $this->tempFilesDirectory = '/tmp';
     parent::setUp();
     $dumps = array(
       $this->getDumpDirectory() . '/Files.php',
@@ -45,7 +52,6 @@ protected function setUp() {
     $executable = new MigrateExecutable($migration, $this);
     $executable->import();
     $this->standalone = TRUE;
-    file_put_contents('/tmp/some-temp-file.jpg', '');
   }
 
   /**
@@ -79,7 +85,7 @@ public function testFiles() {
       ->execute();
     Database::getConnection('default', 'migrate')
       ->update('variable')
-      ->fields(array('value' => serialize('/tmp')))
+      ->fields(array('value' => serialize($this->getTempFilesDirectory())))
       ->condition('name', 'file_directory_temp')
       ->execute();
     $executable = new MigrateExecutable($migration, $this);
@@ -90,7 +96,37 @@ public function testFiles() {
 
     // Ensure that a temporary file has been migrated.
     $file = entity_load('file', 6);
-    $this->assertIdentical('temporary://some-temp-file.jpg', $file->getFileUri());
+    $this->assertIdentical('temporary://' . static::getUniqueFilename(), $file->getFileUri());
+  }
+
+  /**
+   * @return string
+   *   A filename based upon the test.
+   */
+  public static function getUniqueFilename() {
+    return static::$tempFilename;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function migrateDumpAlter(TestBase $test) {
+    // Creates a random filename and updates the source database.
+    $random = new Random();
+    $temp_directory = $test->getTempFilesDirectory();
+    static::$tempFilename = $test->getDatabasePrefix() . $random->name() . '.jpg';
+    $file_path = $temp_directory . '/' . static::$tempFilename;
+    file_put_contents($file_path, '');
+    Database::getConnection('default', 'migrate')
+      ->update('files')
+      ->condition('fid', 6)
+      ->fields(array(
+        'filename' => static::$tempFilename,
+        'filepath' => $file_path,
+      ))
+      ->execute();
+
+    return static::$tempFilename;
   }
 
 }
diff --git a/core/modules/simpletest/src/TestBase.php b/core/modules/simpletest/src/TestBase.php
index a95bade..9a38774 100644
--- a/core/modules/simpletest/src/TestBase.php
+++ b/core/modules/simpletest/src/TestBase.php
@@ -1652,4 +1652,24 @@ protected function config($name) {
     return \Drupal::configFactory()->getEditable($name);
   }
 
+  /**
+   * Gets the database prefix.
+   *
+   * @return string
+   *   The database prefix
+   */
+  public function getDatabasePrefix() {
+    return $this->databasePrefix;
+  }
+
+  /**
+   * Gets the temporary files directory.
+   *
+   * @return string
+   *   The temporary files directory.
+   */
+  public function getTempFilesDirectory() {
+    return $this->tempFilesDirectory;
+  }
+
 }