Issue #7: Trying to fix png image generation on Travis.

Author: drupol

spec/drupol/phptree/Exporter/GraphSpec.php

@@ -25,6 +25,15 @@ public function getMatchers(): array
             'haveSameGraphImageFile' => function ($subject, $key) {
                 $left = (new GraphViz())->setFormat('png')->createImageFile($subject);
 
+                $left = file_get_contents($left);
+                print_r('file_get_contents($left)');
+                print_r($left);
+                print_r(sha1($left));
+
+                print_r('right');
+                print_r(file_get_contents($key));
+                print_r(sha1(file_get_contents($key)));
+                
                 return \sha1(\file_get_contents($left)) === \sha1(\file_get_contents($key));
             },
         ];
@@ -52,7 +61,7 @@ public function it_can_generate_a_graph()
 
         $this
             ->export($tree)
-            ->shouldHaveSameGraphImageFile('tests/fixtures/Exporter/GraphSpec1.png');
+            ->shouldHaveSameGraphImageFile($_SERVER['PWD'] . '/tests/fixtures/Exporter/GraphSpec1.png');
     }
 
     public function it_is_initializable()