Use cat for test since head might not exist on all systems

Author: Martin Qvistgård

tests/CommandTest.php

@@ -226,12 +226,12 @@ public function testCanProvideProcDir()
     }
     public function testCanRunCommandWithStandardInput()
     {
-        $command = new Command('head');
-        $command->addArg('-n', 1);
-        $command->setStdIn("1\n2\n3\n");
+        $command = new Command('/bin/cat');
+        $command->addArg('-T');
+        $command->setStdIn("\t");
         $this->assertTrue($command->execute());
         $this->assertTrue($command->getExecuted());
-        $this->assertEquals("1", $command->getOutput());
+        $this->assertEquals("^I", $command->getOutput());
     }
 
 }