Question

我正在尝试使用EF7 InMemory提供程序进行单元测试，但测试之间InMemory数据库的持久性使我遇到问题。

以下代码演示了我的问题。一个测试将起作用，另一个测试将始终失败。即使我在测试之间将_context设置为null，第二次测试运行也总是有4条记录。

[TestClass]
public class UnitTest1
{

    private SchoolContext _context;

    [TestInitialize]
    public void Setup()
    {
        Random rng = new Random();

        var optionsBuilder = new DbContextOptionsBuilder<SchoolContext>();
        optionsBuilder.UseInMemoryDatabase();

        _context = new SchoolContext(optionsBuilder.Options);
        _context.Students.AddRange(
            new Student { Id = rng.Next(1,10000), Name = "Able" },
            new Student { Id = rng.Next(1,10000), Name = "Bob" }
        );
        _context.SaveChanges();
    }

    [TestCleanup]
    public void Cleanup()
    {
        _context = null;
    }

    [TestMethod]
    public void TestMethod1()
    {
        Assert.AreEqual(2, _context.Students.ToList().Count());
    }

    [TestMethod]
    public void TestMethod2()
    {
        Assert.AreEqual(2, _context.Students.ToList().Count());
    }

}

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class SchoolContext : DbContext
{
    public SchoolContext(DbContextOptions options) : base(options) { }

    public DbSet<Student> Students { get; set; }
}

Answer 1

以下调用将清除内存中的数据存储区。

_context.Database.EnsureDeleted();

Answer 2

有点迟到了，但我也遇到了同样的问题，但我最终做的是。

为每个测试指定不同的数据库名称。

@IBAction func backButtonAction(_ sender: Any) {
   self.presentingViewController?.dismiss(animated: true, completion: nil)
}

这样你就不必添加

optionsBuilder.UseInMemoryDatabase(Guid.NewGuid().ToString());

在所有测试中

Answer 3

我使用如下的DbContext灯具

public class DbContextFixture 
    where TDbContext : DbContext
{
    private readonly DbContextOptions _dbContextOptions = 
        new DbContextOptionsBuilder()
            .UseInMemoryDatabase("_", new InMemoryDatabaseRoot())
            .Options;

    public TDbContext CreateDbContext()
    {
        return (TDbContext)(typeof(TDbContext)
            .GetConstructor(new[] { typeof(DbContextOptions) })
            .Invoke(new[] { _dbContextOptions }));
    }
}

您现在可以轻松完成

public class MyRepositoryTests : IDisposable {
    private SchoolContext _context;
    private DbContextFixture<ApplicationDbContext> _dbContextFixture;

    [TestInitialize]
    public void Setup() {
        _dbContextFixture = new DbContextFixture<ApplicationDbContext>();
        _context = _dbContextFixture.CreateDbContext();
        _context.Students.AddRange(
            new Student { Id = rng.Next(1,10000), Name = "Able" },
            new Student { Id = rng.Next(1,10000), Name = "Bob" }
        );
        _context.SaveChanges();
    }

    [TestCleanup]
    public void Cleanup()
        _context.Dispose();
        _dbContextFixture = null;
    }

    [TestMethod]
    public void TestMethod1()
    {
        Assert.AreEqual(2, _context.Students.ToList().Count());
    }

    [TestMethod]
    public void TestMethod2()
    {
        Assert.AreEqual(2, _context.Students.ToList().Count());
    }
}

此解决方案是线程安全的。有关详细信息，请参见我的blog。

Answer 4

我会结合两个答案。如果并行运行测试，则可能在运行另一个测试的过程中删除了一个数据库，因此在运行30多个测试时，我会看到偶发的故障。

给它一个随机的数据库名称，并确保在测试完成后将其删除。

public class MyRepositoryTests : IDisposable {
  private SchoolContext _context;

  [TestInitialize]
  public void Setup() {
    var options = new DbContextOptionsBuilder<ApplicationDbContext>()
      // Generate a random db name
      .UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString())
      .Options;
      _context = new ApplicationDbContext(options);
  }

  [TestCleanup]
  public void Cleanup()
    _context.Database.EnsureDeleted(); // Remove from memory
    _context.Dispose();
  }
}

Answer 5

只需将您的DbContextOptionsBuilder代码定义更改如下：

        var databaseName = "DatabaseNameHere";
        var dbContextOption = new DbContextOptionsBuilder<SchoolContext>()
                                    .UseInMemoryDatabase(databaseName, new InMemoryDatabaseRoot())
                                    .Options;

新的InMemoryDatabaseRoot（）正在创建新的数据库，而ID不再存在。因此，您现在不需要：

       [TestCleanup]
       public void Cleanup()
       {
           _context = null;
       }

Answer 6

此处的示例通过RemoveRange实现此目的：https://docs.microsoft.com/en-us/aspnet/core/test/integration-tests?view=aspnetcore-3.1

db.<Entity>.RemoveRange(db.<entity>);

Answer 7

这是我的2分方法，可以使每个单元测试彼此隔离。我正在使用C＃7，XUnit和EF core 3.1。

示例TestFixture类。

public class SampleIntegrationTestFixture : IDisposable
    {

        public DbContextOptionsBuilder<SampleDbContext> SetupInMemoryDatabase()
            => new DbContextOptionsBuilder<SampleDbContext>().UseInMemoryDatabase("MyInMemoryDatabase");

 private IEnumerable<Student> CreateStudentStub()
            => new List<Student>
            {
            new Student { Id = rng.Next(1,10000), Name = "Able" },
            new Student { Id = rng.Next(1,10000), Name = "Bob" }
            };

        public void Dispose()
        {
        }
   }

示例IntegrationTest类

 public class SampleJobIntegrationTest : IClassFixture<SampleIntegrationTestFixture >
 {
    private DbContextOptionsBuilder<SampleDbContext> DbContextBuilder { get; }
    private SampleDbContext SampleDbContext { get; set; }

 public SampleJobIntegrationTest(SampleIntegrationTestFixture 
 sampleIntegrationTestFixture )
  {
        SampleIntegrationTestFixture = sampleIntegrationTestFixture ;

        SampleDbContextBuilder = sampleIntegrationTestFixture .SetupInMemoryDatabase();
  }



  [Fact]
    public void TestMethod1()
    {
using(SampleDbContext = new SampleDbContext(SampleDbContextBuilder.Options))

        var students= SampleIntegrationTestFixture.CreateStudentStub();
            {
            SampleDbContext.Students.AddRange(students);

        SampleDbContext.SaveChanges();

  Assert.AreEqual(2, _context.Students.ToList().Count());

                SampleDbContext.Database.EnsureDeleted();
            }
      
    }

如何在单元测试之间重置EF7 InMemory提供程序？

7 个答案: