@Test
  public void shouldReportUnknownUser() {
    // given
    String user = "******";
    given(dataSource.getAuth(user)).willReturn(null);
    CommandSender sender = mock(CommandSender.class);

    // when
    command.executeCommand(sender, Collections.singletonList(user));

    // then
    verify(service).send(sender, MessageKey.UNKNOWN_USER);
  }
  @Test
  public void shouldReturnEmail() {
    // given
    String user = "******";
    String email = "*****@*****.**";
    PlayerAuth auth = mock(PlayerAuth.class);
    given(auth.getEmail()).willReturn(email);
    given(dataSource.getAuth(user)).willReturn(auth);
    CommandSender sender = mock(CommandSender.class);

    // when
    command.executeCommand(sender, Collections.singletonList(user));

    // then
    verify(sender).sendMessage(argThat(containsString(email)));
  }