Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/phpspec/prophecy/spec/Prophecy/Prediction/CallbackPredictionSpec.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace spec\Prophecy\Prediction;
+
+use PhpSpec\ObjectBehavior;
+
+use RuntimeException;
+
+class CallbackPredictionSpec extends ObjectBehavior
+{
+    function let()
+    {
+        $this->beConstructedWith('get_class');
+    }
+
+    function it_is_prediction()
+    {
+        $this->shouldHaveType('Prophecy\Prediction\PredictionInterface');
+    }
+
+    /**
+     * @param \Prophecy\Prophecy\ObjectProphecy $object
+     * @param \Prophecy\Prophecy\MethodProphecy $method
+     * @param \Prophecy\Call\Call               $call
+     */
+    function it_proxies_call_to_callback($object, $method, $call)
+    {
+        $returnFirstCallCallback = function ($calls, $object, $method) {
+            throw new RuntimeException;
+        };
+
+        $this->beConstructedWith($returnFirstCallCallback);
+
+        $this->shouldThrow('RuntimeException')->duringCheck(array($call), $object, $method);
+    }
+}