Тестирование C#: xUnit + Moq

1dotnet new xunit -n MyApp.Tests
2cd MyApp.Tests
3dotnet add reference ../MyApp
4dotnet add package Moq

1using Xunit;
2
3public class CalculatorTests
4{
5    [Fact]
6    public void Add_TwoNumbers_ReturnsSum()
7    {
8        var calc = new Calculator();
9        var result = calc.Add(2, 3);
10        Assert.Equal(5, result);
11    }
12
13    [Fact]
14    public void Divide_ByZero_ThrowsException()
15    {
16        var calc = new Calculator();
17        Assert.Throws<DivideByZeroException>(() => calc.Divide(1, 0));
18    }
19}

1public class PrimeNumberTests
2{
3    [Theory]
4    [InlineData(2)]
5    [InlineData(3)]
6    [InlineData(5)]
7    [InlineData(7)]
8    [InlineData(11)]
9    public void IsPrime_ReturnsTrue_ForPrimeNumbers(int number)
10    {
11        Assert.True(PrimeChecker.IsPrime(number));
12    }
13
14    [Theory]
15    [InlineData(4)]
16    [InlineData(6)]
17    [InlineData(8)]
18    [InlineData(9)]
19    public void IsPrime_ReturnsFalse_ForNonPrimeNumbers(int number)
20    {
21        Assert.False(PrimeChecker.IsPrime(number));
22    }
23}

1// Equal / NotEqual
2Assert.Equal(expected, actual);
3Assert.NotEqual(1, 2);
4
5// True / False
6Assert.True(condition);
7Assert.False(condition);
8
9// Null / NotNull
10Assert.Null(obj);
11Assert.NotNull(obj);
12
13// Collections
14Assert.Contains(item, collection);
15Assert.DoesNotContain(item, collection);
16Assert.Empty(collection);
17Assert.Single(collection);
18Assert.Equal(new[] { 1, 2, 3 }, collection);
19
20// Strings
21Assert.StartsWith("Hello", str);
22Assert.EndsWith("World", str);
23Assert.Contains("lo Wo", str);
24
25// Throws
26Assert.Throws<Exception>(() => method());
27await Assert.ThrowsAsync<Exception>(() => methodAsync());

1using Moq;
2
3public class UserServiceTests
4{
5    [Fact]
6    public async Task GetUser_ReturnsUser()
7    {
8        // Arrange
9        var mockRepo = new Mock<IUserRepository>();
10        mockRepo.Setup(r => r.GetByIdAsync(1))
11            .ReturnsAsync(new User { Id = 1, Name = "John" });
12        
13        var service = new UserService(mockRepo.Object);
14        
15        // Act
16        var user = await service.GetUserAsync(1);
17        
18        // Assert
19        Assert.Equal("John", user.Name);
20        mockRepo.Verify(r => r.GetByIdAsync(1), Times.Once);
21    }
22}

1// Проверка, что метод был вызван ровно один раз
2mockRepo.Verify(r => r.SaveAsync(It.IsAny<User>()), Times.Once);
3
4// Проверка, что метод НЕ был вызван
5mockRepo.Verify(r => r.DeleteAsync(It.IsAny<int>()), Times.Never);
6
7// Проверка с аргументами
8mockRepo.Verify(r => r.GetByIdAsync(1), Times.Once);
9mockRepo.Verify(r => r.GetByIdAsync(It.Is<int>(id => id > 0)), Times.AtLeastOnce);

1User savedUser = null;
2mockRepo.Setup(r => r.SaveAsync(It.IsAny<User>()))
3    .Callback<User>(u => savedUser = u)
4    .ReturnsAsync(new User { Id = 1 });

1mockRepo.Setup(r => r.GetByIdAsync(999))
2    .ThrowsAsync(new NotFoundException("User not found"));

1public class OrderServiceTests
2{
3    private readonly Mock<IOrderRepository> _orderRepo;
4    private readonly Mock<IEmailService> _emailService;
5    private readonly OrderService _service;
6
7    public OrderServiceTests()
8    {
9        _orderRepo = new Mock<IOrderRepository>();
10        _emailService = new Mock<IEmailService>();
11        _service = new OrderService(_orderRepo.Object, _emailService.Object);
12    }
13
14    [Fact]
15    public async Task CreateOrder_SavesAndSendsEmail()
16    {
17        var dto = new CreateOrderDto { ProductId = 1, Quantity = 2 };
18        
19        await _service.CreateOrderAsync(dto);
20        
21        _orderRepo.Verify(r => r.SaveAsync(It.IsAny<Order>()), Times.Once);
22        _emailService.Verify(e => e.SendAsync(
23            It.IsAny<string>(),
24            It.IsAny<string>(),
25            It.IsAny<string>()),
26            Times.Once);
27    }
28}