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

vendor/phpspec/prophecy/spec/Prophecy/Argument/Token/CallbackTokenSpec.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace spec\Prophecy\Argument\Token;
+
+use PhpSpec\ObjectBehavior;
+
+class CallbackTokenSpec extends ObjectBehavior
+{
+    function let()
+    {
+        $this->beConstructedWith('get_class');
+    }
+
+    function it_implements_TokenInterface()
+    {
+        $this->shouldBeAnInstanceOf('Prophecy\Argument\Token\TokenInterface');
+    }
+
+    function it_is_not_last()
+    {
+        $this->shouldNotBeLast();
+    }
+
+    function it_scores_7_if_argument_matches_callback()
+    {
+        $this->beConstructedWith(function ($argument) { return 2 === $argument; });
+
+        $this->scoreArgument(2)->shouldReturn(7);
+    }
+
+    function it_does_not_scores_if_argument_does_not_match_callback()
+    {
+        $this->beConstructedWith(function ($argument) { return 2 === $argument; });
+
+        $this->scoreArgument(5)->shouldReturn(false);
+    }
+
+    function its_string_representation_should_tell_that_its_callback()
+    {
+        $this->__toString()->shouldReturn('callback()');
+    }
+}