public async Task Given_A_Card_Name_Should_Invoke_CardByName_Method_Once() { // Arrange const string cardName = "Blue-Eyes White Dragon"; _cardRepository.CardByName(Arg.Any <string>()).Returns(new Card()); // Act await _sut.CardByName(cardName); // Assert await _cardRepository.Received(1).CardByName(Arg.Is(cardName)); }