diff --git a/core/modules/rest/lib/Drupal/rest/Tests/CreateTest.php b/core/modules/rest/lib/Drupal/rest/Tests/CreateTest.php
index 89eb312..c5b298a 100644
--- a/core/modules/rest/lib/Drupal/rest/Tests/CreateTest.php
+++ b/core/modules/rest/lib/Drupal/rest/Tests/CreateTest.php
@@ -53,7 +53,7 @@ public function testCreate() {
 
     // Get the new entity ID from the location header and try to read it from
     // the database.
-    $location_url = $this->responseHeaders['location'];
+    $location_url = $this->drupalGetHeader('location');
     $url_parts = explode('/', $location_url);
     $id = end($url_parts);
     $loaded_entity = entity_load($entity_type, $id);
@@ -68,11 +68,7 @@ public function testCreate() {
       $this->assertEqual($send_value, $actual_value, 'Created property ' . $property . ' expected: ' . $send_value . ', actual: ' . $actual_value);
     }
 
-    // Reset cURL here because it is confused from our previously used cURL
-    // options.
-    $this->drupalLogout();
-    unset($this->curlHandle);
-    $this->drupalLogin($account);
+    $loaded_entity->delete();
     // Try to create an entity without the CSRF token.
     $this->curlExec(array(
       CURLOPT_HTTPGET => FALSE,
@@ -84,20 +80,20 @@ public function testCreate() {
       CURLOPT_HTTPHEADER => array('Content-Type: application/vnd.drupal.ld+json'),
     ));
     $this->assertResponse(403);
+    $this->assertFalse(entity_load_multiple($entity_type, NULL, TRUE), 'No entity has been created in the database.');
 
     // Try to create an entity without proper permissions.
     $this->drupalLogout();
     $this->httpRequest('entity/' . $entity_type, 'POST', $serialized, 'application/vnd.drupal.ld+json');
     $this->assertResponse(403);
+    $this->assertFalse(entity_load_multiple($entity_type, NULL, TRUE), 'No entity has been created in the database.');
 
-    // Reset cURL here because it is confused from our previously used cURL
-    // options.
-    unset($this->curlHandle);
     // Try to create a resource which is not web API enabled.
     $this->enableService(FALSE);
     $this->drupalLogin($account);
     $this->httpRequest('entity/entity_test', 'POST', $serialized, 'application/vnd.drupal.ld+json');
     $this->assertResponse(404);
+    $this->assertFalse(entity_load_multiple($entity_type, NULL, TRUE), 'No entity has been created in the database.');
 
     // @todo Once EntityNG is implemented for other entity types add a security
     // test. It should not be possible for example to create a test entity on a
diff --git a/core/modules/rest/lib/Drupal/rest/Tests/DeleteTest.php b/core/modules/rest/lib/Drupal/rest/Tests/DeleteTest.php
index 66f85c4..ed2d04d 100644
--- a/core/modules/rest/lib/Drupal/rest/Tests/DeleteTest.php
+++ b/core/modules/rest/lib/Drupal/rest/Tests/DeleteTest.php
@@ -40,9 +40,6 @@ public function testDelete() {
       // Create a user account that has the required permissions to delete
       // resources via the web API.
       $account = $this->drupalCreateUser(array('restful delete entity:' . $entity_type));
-      // Reset cURL here because it is confused from our previously used cURL
-      // options.
-      unset($this->curlHandle);
       $this->drupalLogin($account);
 
       // Create an entity programmatically.
@@ -74,9 +71,6 @@ public function testDelete() {
     // Try to delete a resource which is not web API enabled.
     $this->enableService(FALSE);
     $account = $this->drupalCreateUser();
-    // Reset cURL here because it is confused from our previously used cURL
-    // options.
-    unset($this->curlHandle);
     $this->drupalLogin($account);
     $this->httpRequest('entity/user/' . $account->id(), 'DELETE');
     $user = entity_load('user', $account->id(), TRUE);
diff --git a/core/modules/rest/lib/Drupal/rest/Tests/RESTTestBase.php b/core/modules/rest/lib/Drupal/rest/Tests/RESTTestBase.php
index 57a3f00..f7dbdb6 100644
--- a/core/modules/rest/lib/Drupal/rest/Tests/RESTTestBase.php
+++ b/core/modules/rest/lib/Drupal/rest/Tests/RESTTestBase.php
@@ -15,13 +15,6 @@
 abstract class RESTTestBase extends WebTestBase {
 
   /**
-   * Stores HTTP response headers from the last HTTP request.
-   *
-   * @var array
-   */
-  protected $responseHeaders;
-
-  /**
    * Helper function to issue a HTTP request with simpletest's cURL.
    *
    * @param string $url
@@ -203,7 +196,20 @@ protected function enableService($resource_type) {
    *   TRUE if the assertion succeeded, FALSE otherwise.
    */
   protected function assertHeader($header, $value, $message = '', $group = 'Browser') {
-    $match = isset($this->responseHeaders[$header]) && $this->responseHeaders[$header] == $value;
-    return $this->assertTrue($match, $message ? $message : 'HTTP response header ' . $header . ' with value ' . $value . ' found.', $group);
+    $header_value = $this->drupalGetHeader($header);
+    return $this->assertTrue($header_value == $value, $message ? $message : 'HTTP response header ' . $header . ' with value ' . $value . ' found.', $group);
+  }
+
+  /**
+   * Overrides WebTestBase::drupalLogin().
+   */
+  protected function drupalLogin($user) {
+    if (isset($this->curlHandle)) {
+      // cURL quirk: when setting CURLOPT_CUSTOMREQUEST to anything other than
+      // POST in httpRequest() it has to be restored to POST here. Otherwise the
+      // POST request to login a user will not work.
+      curl_setopt($this->curlHandle, CURLOPT_CUSTOMREQUEST, 'POST');
+    }
+    parent::drupalLogin($user);
   }
 }
diff --git a/core/modules/rest/lib/Drupal/rest/Tests/ReadTest.php b/core/modules/rest/lib/Drupal/rest/Tests/ReadTest.php
index 874ad13..0578fc3 100644
--- a/core/modules/rest/lib/Drupal/rest/Tests/ReadTest.php
+++ b/core/modules/rest/lib/Drupal/rest/Tests/ReadTest.php
@@ -42,9 +42,6 @@ public function testRead() {
       // Create a user account that has the required permissions to delete
       // resources via the web API.
       $account = $this->drupalCreateUser(array('restful get entity:' . $entity_type));
-      // Reset cURL here because it is confused from our previously used cURL
-      // options.
-      unset($this->curlHandle);
       $this->drupalLogin($account);
 
       // Create an entity programmatically.
@@ -80,9 +77,6 @@ public function testRead() {
     }
     // Try to read a resource which is not web API enabled.
     $account = $this->drupalCreateUser();
-    // Reset cURL here because it is confused from our previously used cURL
-    // options.
-    unset($this->curlHandle);
     $this->drupalLogin($account);
     $response = $this->httpRequest('entity/user/' . $account->id(), 'GET', NULL, 'application/vnd.drupal.ld+json');
     $this->assertResponse(404);
diff --git a/core/modules/rest/lib/Drupal/rest/Tests/UpdateTest.php b/core/modules/rest/lib/Drupal/rest/Tests/UpdateTest.php
index 83729aa..fa65a2f 100644
--- a/core/modules/rest/lib/Drupal/rest/Tests/UpdateTest.php
+++ b/core/modules/rest/lib/Drupal/rest/Tests/UpdateTest.php
@@ -89,9 +89,6 @@ public function testPatchUpdate() {
 
     // Try to update a resource which is not web API enabled.
     $this->enableService(FALSE);
-    // Reset cURL here because it is confused from our previously used cURL
-    // options.
-    unset($this->curlHandle);
     $this->drupalLogin($account);
     $this->httpRequest('entity/' . $entity_type . '/' . $entity->id(), 'PATCH', $serialized, 'application/vnd.drupal.ld+json');
     $this->assertResponse(404);
@@ -162,9 +159,6 @@ public function testPutUpdate() {
 
     // Try to update a resource which is not web API enabled.
     $this->enableService(FALSE);
-    // Reset cURL here because it is confused from our previously used cURL
-    // options.
-    unset($this->curlHandle);
     $this->drupalLogin($account);
     $this->httpRequest('entity/' . $entity_type . '/' . $entity->id(), 'PUT', $serialized, 'application/vnd.drupal.ld+json');
     $this->assertResponse(404);