浅谈.Net Core后端单元测试的实现

[Fact]
public async Task VisitDataCompressExport_ShouldReturnEmptyResult_WhenFileTokenDoesNotExist()
{
  // arrange
  var mockFiletokenStore = new Mock<IFileTokenStore>();
  mockFiletokenStore
    .Setup(it => it.Get(It.IsAny<string>()))
    .Returns(string.Empty);

  var controller = new StatController(
    mockFiletokenStore.Object,
    null);

  // act
  var actual = await controller.VisitDataCompressExport("faketoken");

  // assert
  Assert.IsType<EmptyResult>(actual);
}

[Theory]
[InlineData(null)]
[InlineData("a")]
public void Add_InputNullOrAlphabetic_ThrowsArgumentException(string input)
{
  // arrange
  var stringCalculator = new StringCalculator();

  // act
  Action actual = () => stringCalculator.Add(input);

  // assert
  Assert.Throws<ArgumentException>(actual);
}

<被测试方法全名>_<期望的结果>_<给予的条件>

// 例子
[Fact]
public void Add_InputNullOrAlphabetic_ThrowsArgumentException()
{
 ...
}

// xUnit
Assert.True()
Assert.Equal()

// MsTest
Assert.IsTrue()
Assert.AreEqual()

public class UserController
{
  private readonly IUserService _userService;
  
  public UserController(IUserService userService)
  {
    _userService = userService;
  }
  
  [HttpGet("{id}")]
  public IActionResult GetUser(int id)
  {
    var user = _userService.GetUser(id);
    
    if (user == null)
    {
      return NotFound();
    }
    else
    {
      ...
    }
  }
}

[Fact]
public void GetUser_ShouldReturnNotFound_WhenCannotFoundUser()
{
  // arrange
  // 新建一个IUserService的mock对象
  var mockUserService = new Mock<IUserService>();
  // 使用moq对IUserService的GetUs方法进行mock: 当入参为233时返回null
  mockUserService
   .Setup(it => it.GetUser(233))
   .Return((User)null);
  var controller = new UserController(mockUserService.Object);
  
  // act
  var actual = controller.GetUser(233) as NotFoundResult;
  
  // assert
  // 验证调用过userService的GetUser方法一次，且入参为233
  mockUserService.Verify(it => it.GetUser(233), Times.AtMostOnce());
}

[Fact]
public void IntroductoryTest()
{
  // arrange
  Fixture fixture = new Fixture();

  int expectedNumber = fixture.Create<int>();
  MyClass sut = fixture.Create<MyClass>();
  
  // act
  int result = sut.Echo(expectedNumber);
  
  // assert
  Assert.Equal(expectedNumber, result);
}

[Theory, AutoData]
public void IntroductoryTest(
  int expectedNumber, MyClass sut)
{
  // act
  int result = sut.Echo(expectedNumber);
  
  // assert
  Assert.Equal(expectedNumber, result);
}

// 1. 测试时创建一个模拟的List<T>
var users = new List<UserEntity>()
{
 new UserEntity{LastName = "ExistLastName", DateOfBirth = DateTime.Parse("01/20/2012")},
 ...
};

// 2. 通过扩展方法转换成DbSet<UserEntity>
var mockUsers = users.AsQueryable().BuildMock();

// 3. 赋值给给mock的DbContext中的Users属性
var mockDbContext = new Mock<DbContext>();
mockDbContext
 .Setup(it => it.Users)
 .Return(mockUsers);

public static class LoggerHelper
{
  public static Mock<ILogger<T>> LoggerMock<T>() where T : class
  {
    return new Mock<ILogger<T>>();
  }

  public static void VerifyLog<T>(this Mock<ILogger<T>> loggerMock, LogLevel level, string containMessage, Times times)
  {
    loggerMock.Verify(
    x => x.Log(
      level,
      It.IsAny<EventId>(),
      It.Is<It.IsAnyType>((o, t) => o.ToString().Contains(containMessage)),
      It.IsAny<Exception>(),
      (Func<It.IsAnyType, Exception, string>)It.IsAny<object>()),
    times);
  }

  public static void VerifyLog<T>(this Mock<ILogger<T>> loggerMock, LogLevel level, Times times)
  {
    loggerMock.Verify(
    x => x.Log(
      level,
      It.IsAny<EventId>(),
      It.IsAny<It.IsAnyType>(),
      It.IsAny<Exception>(),
      (Func<It.IsAnyType, Exception, string>)It.IsAny<object>()),
    times);
  }
}

[Fact]
public void Echo_ShouldLogInformation()
{
  // arrange
  var mockLogger = LoggerHelpe.LoggerMock<UserController>();
  var controller = new UserController(mockLogger.Object);
  
  // act
  controller.Echo();
  
  // assert
  mockLogger.VerifyLog(LogLevel.Information, "hello", Times.Once());
}