@Test
public void catDirectoryTest() throws IOException {

  String expected = "Successfully created directory /testDir\n\n" +
          "Path /testDir must be a file\n";
  InterpreterResult output = alluxioInterpreter.interpret("mkdir /testDir" +
          "\ncat /testDir", null);
  Assert.assertEquals(Code.ERROR, output.code());
  Assert.assertEquals(expected, output.message());
}