public void ShuffleCards_ShouldReturnShuffeldCards() { // Arrange var cards = _fixture.CreateMany <Card>(52).ToList(); Card[] originalCopy = new Card[52]; cards.CopyTo(originalCopy); // Act CardsGenerator.ShuffleCards(cards); // Assert var diff = 0; for (int i = 0; i < 52; i++) { if (cards[i].Value != originalCopy[i].Value) { diff++; } } Assert.AreNotEqual(diff, 0); }