diff --git includes/file.inc includes/file.inc
index c4fedfe..dcc81aa 100644
--- includes/file.inc
+++ includes/file.inc
@@ -654,10 +654,11 @@ function file_unmanaged_copy($source, $destination = NULL, $replace = FILE_EXIST
     $destination = file_build_uri(basename($source));
   }
 
-  // Assert that the destination contains a valid stream.
+  // Assert that the destination contains an allowed scheme.
   $destination_scheme = file_uri_scheme($destination);
   if (!$destination_scheme || !file_stream_wrapper_valid_scheme($destination_scheme)) {
     drupal_set_message(t('The specified file %file could not be copied, because the destination %destination is invalid. This is often caused by improper use of file_unmanaged_copy() or a missing stream wrapper.', array('%file' => $original_source, '%destination' => $destination)), 'error');
+    return FALSE;
   }
 
   // Prepare the destination directory.
diff --git modules/file/tests/file.test modules/file/tests/file.test
index 3e6a0c4..0d67d26 100644
--- modules/file/tests/file.test
+++ modules/file/tests/file.test
@@ -116,11 +116,11 @@ class FileFieldTestCase extends DrupalWebTestCase {
     if (is_numeric($nid_or_type)) {
       $node = node_load($nid_or_type);
       $delta = isset($node->$field_name) ? count($node->$field_name) : 0;
-      $edit['files[' . $field_name . '_' . LANGUAGE_NONE . '_' . $delta . ']'] = realpath($file->uri);
+      $edit['files[' . $field_name . '_' . LANGUAGE_NONE . '_' . $delta . ']'] = drupal_realpath($file->uri);
       $this->drupalPost('node/' . $nid_or_type . '/edit', $edit, t('Save'));
     }
     else {
-      $edit['files[' . $field_name . '_' . LANGUAGE_NONE . '_0]'] = realpath($file->uri);
+      $edit['files[' . $field_name . '_' . LANGUAGE_NONE . '_0]'] = drupal_realpath($file->uri);
       $type_name = str_replace('_', '-', $nid_or_type);
       $this->drupalPost('node/add/' . $type_name, $edit, t('Save'));
     }
@@ -149,7 +149,7 @@ class FileFieldTestCase extends DrupalWebTestCase {
    */
   function replaceNodeFile($file, $field_name, $nid, $new_revision = TRUE) {
     $edit = array(
-      'files[' . $field_name . '_' . LANGUAGE_NONE . '_0]' => realpath($file->uri),
+      'files[' . $field_name . '_' . LANGUAGE_NONE . '_0]' => drupal_realpath($file->uri),
       'revision' => (string) (int) $new_revision,
     );
 
@@ -504,6 +504,8 @@ class FileFieldValidateTestCase extends FileFieldTestCase {
 
     // Create a new node with the uploaded file.
     $nid = $this->uploadNodeFile($test_file, $field_name, $type_name);
+    $this->assertTrue($nid !== FALSE, t('uploadNodeFile(@test_file, @field_name, @type_name) succeeded', array('@test_file' => $test_file->uri, '@field_name' => $field_name, '@type_name' => $type_name)));
+
     $node = node_load($nid, NULL, TRUE);
 
     $node_file = (object) $node->{$field_name}[LANGUAGE_NONE][0];
diff --git modules/image/image.test modules/image/image.test
index 0738e05..f414376 100644
--- modules/image/image.test
+++ modules/image/image.test
@@ -94,7 +94,7 @@ class ImageFieldTestCase extends DrupalWebTestCase {
     $edit = array(
       'title' => $this->randomName(),
     );
-    $edit['files[' . $field_name . '_' . LANGUAGE_NONE . '_0]'] = realpath($image->uri);
+    $edit['files[' . $field_name . '_' . LANGUAGE_NONE . '_0]'] = drupal_realpath($image->uri);
     $this->drupalPost('node/add/' . $type, $edit, t('Save'));
 
     // Retrieve ID of the newly created node from the current URL.
@@ -765,7 +765,7 @@ class ImageFieldDisplayTestCase extends ImageFieldTestCase {
     // Add a default image to the imagefield instance.
     $images = $this->drupalGetTestFiles('image');
     $edit = array(
-      'files[field_settings_default_image]' => realpath($images[0]->uri),
+      'files[field_settings_default_image]' => drupal_realpath($images[0]->uri),
     );
     $this->drupalPost('admin/structure/types/manage/article/fields/' . $field_name, $edit, t('Save settings'));
     // Clear field info cache so the new default image is detected.
diff --git modules/simpletest/drupal_web_test_case.php modules/simpletest/drupal_web_test_case.php
index b060c53..6f20e62 100644
--- modules/simpletest/drupal_web_test_case.php
+++ modules/simpletest/drupal_web_test_case.php
@@ -896,9 +896,8 @@ class DrupalWebTestCase extends DrupalTestCase {
       // Copy other test files from simpletest.
       $original = drupal_get_path('module', 'simpletest') . '/files';
       $files = file_scan_directory($original, '/(html|image|javascript|php|sql)-.*/');
-      $destination_path = file_directory_path('public');
       foreach ($files as $file) {
-        file_unmanaged_copy($file->uri, $destination_path);
+        file_unmanaged_copy($file->uri, 'public://' . $file->filename);
       }
 
       $this->generatedTestFiles = TRUE;
@@ -907,7 +906,7 @@ class DrupalWebTestCase extends DrupalTestCase {
     $files = array();
     // Make sure type is valid.
     if (in_array($type, array('binary', 'html', 'image', 'javascript', 'php', 'sql', 'text'))) {
-      $files = file_scan_directory(file_directory_path('public'), '/' . $type . '\-.*/');
+      $files = file_scan_directory('public://', '/' . $type . '\-.*/');
 
       // If size is set then remove any files that are not of that size.
       if ($size !== NULL) {