Skip tests on hhvm

tests/Composer/Test/CacheTest.php

@@ -46,6 +46,10 @@ class CacheTest extends TestCase
 
     public function testRemoveOutdatedFiles()
     {
+        if (defined('HHVM_VERSION')) {
+            $this->markTestSkipped('Test causes intermittent failures with HHVM on Travis');
+        }
+
         // sleeping a bit to let the filesystem cool down on travis or it has intermittent failures
         usleep(50000);
 
@@ -69,6 +73,10 @@ class CacheTest extends TestCase
 
     public function testRemoveFilesWhenCacheIsTooLarge()
     {
+        if (defined('HHVM_VERSION')) {
+            $this->markTestSkipped('Test causes intermittent failures with HHVM on Travis');
+        }
+
         // sleeping a bit to let the filesystem cool down on travis or it has intermittent failures
         usleep(50000);