如何MOQ实体框架SaveChangesAsync？ [英] How to moq Entity Framework SaveChangesAsync?

问题描述

Mock<IDbContext> dbContext;

[TestFixtureSetUp]
public void SetupDbContext()
{
    dbContext = new Mock<IDbContext>();
    dbContext.Setup(c => c.SaveChanges()).Verifiable();
    dbContext.Setup(c => c.SaveChangesAsync()).Verifiable();
    dbContext.Setup(c => c.Customers.Add(It.IsAny<Customer>()))
             .Returns(It.IsAny<Customer>()).Verifiable();
}

[Test]
public async Task AddCustomerAsync()
{
    //Arrange
    var repository = new EntityFrameworkRepository(dbContext.Object);
    var customer = new Customer() { FirstName = "Larry", LastName = "Hughes" };

    //Act
    await repository.AddCustomerAsync(customer);

    //Assert
    dbContext.Verify(c => c.Customers.Add(It.IsAny<Customer>()));
    dbContext.Verify(c => c.SaveChangesAsync());
}

[Test]
public void AddCustomer()
{
    //Arrange
    var repository = new EntityFrameworkRepository(dbContext.Object);
    var customer = new Customer() { FirstName = "Larry", LastName = "Hughes" };

    //Act
    repository.AddCustomer(customer);

    //Assert
    dbContext.Verify(c => c.Customers.Add(It.IsAny<Customer>()));
    dbContext.Verify(c => c.SaveChanges());
}

这就是我想要的测试：

public class EntityFrameworkRepository
{
    private readonly IDbContext DBContext;

    public EntityFrameworkRepository(IDbContext context)
    {
        DBContext = context;
    }

    public async Task AddCustomerAsync(Customer customer)
    {
        DBContext.Customers.Add(customer);
        await DBContext.SaveChangesAsync();
    }

    public void AddCustomer(Customer customer)
    {
        DBContext.Customers.Add(customer);
        DBContext.SaveChanges();
    }
}

AddCustomers 测试通过。

AddCustomersAsync 测试失败，我一直在呼唤后得到一个NullReferenceException 等待DbContext.SaveChangesAsync（）。

AddCustomersAsync test fails, I keep getting a NullReferenceException after calling await DbContext.SaveChangesAsync().

在
  MasonOgCRM.DataAccess.EF.EntityFrameworkRepository.d__2.MoveNext（）
  在
  C:\\Users\\Mason\\Desktop\\Repositories\\masonogcrm\\src\\DataAccess.EFRepository\\EntityFrameworkRepository.cs:line
  43

at MasonOgCRM.DataAccess.EF.EntityFrameworkRepository.d__2.MoveNext() in C:\Users\Mason\Desktop\Repositories\masonogcrm\src\DataAccess.EFRepository\EntityFrameworkRepository.cs:line 43

我看不到任何东西，在我的code空。 的DbContext 不为空。 AddCustomers 的等效试验这是与不是异步除外相同的运行正常。我怀疑我没有在 SetupDBContext（）执行的 SaveChangesAsync 正确的设置，但我不知道该怎么办法进行修复。

I can't see anything that's null in my code. DbContext is not null. The equivalent test of AddCustomers which is identical with the exception of not being async runs as expected. I suspect I haven't performed a correct setup of SaveChangesAsync in SetupDBContext() but I don't know what to do to fix it.

推荐答案

您是对的出现问题，因为你设置的一个不正确:: dbContext.Setup（C =＆GT; c.SaveChangesAsync（） ）.Verifiable（）;

You are right the problem occurs because one of your setups incorrect :: dbContext.Setup(c => c.SaveChangesAsync()).Verifiable();.

该方法返回一个工作键，你忘了返回工作因此，空的回报。

The method return a Task and you forgot to return a Task therefore null returns.

您可以删除 dbContext.Setup（C =＆GT; c.SaveChangesAsync（））可验证（）; 或
更改设置来是这样的：

You can remove dbContext.Setup(c => c.SaveChangesAsync()).Verifiable(); or change the setup to something like:

dbContext.Setup(c => c.SaveChangesAsync()).Returns(() => Task.Run(() =>{})).Verifiable();

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