Entity Framework Core 2.2 在单元测试时拆卸后未重置

Question

我正在尝试编写一些单元测试来尽可能多地覆盖我的 api，但我决定使用 InMemory 提供程序而不是使用数据库，而不是测试 EF 是否有效, 而不是我的植入是正确的，但我运行正在进入的是一个奇怪的副作用。

基本上发生的是被播种的对象的 id 值，不会在每次测试后重置。

在 MSTest 中，我实施了一个设置来为每个测试创建一个新的数据库上下文，为每个测试提供一个新名称运行并且确保在为我的数据库做种之前调用 EnsureCreated() .此外，我还实施了 TearDown 以确保正确处理数据库。

[TestClass]
public class CountryTests
{
    private CdiContext Context { get; set; }

    [TestInitialize]
    public void Setup()
    {
        DbContextOptions<CdiContext> options = new DbContextOptionsBuilder<CdiContext>()
            .UseInMemoryDatabase(databaseName: $"{Guid.NewGuid()}")
            .Options;

        Context = new CdiContext(options);
        Context.Database.EnsureCreated();
        Seed();
    }

    [TestCleanup]
    public void TearDown()
    {
        Context.Database.EnsureDeleted();
    }

    private void Seed()
    {
        var service = new CoreDataService(Context);

        var regions = new List<Region>
        {
            new Region
            {
                Name = "Asia",
                State = RecordState.Active,
                Created = DateTime.Now,
                UserId = Guid.NewGuid().ToString()
            },

            new Region
            {
                Name = "Africa",
                State = RecordState.Active,
                Created = DateTime.Now,
                UserId = Guid.NewGuid().ToString()
            },

            new Region
            {
                Name = "South America",
                State = RecordState.Active,
                Created = DateTime.Now,
                UserId = Guid.NewGuid().ToString()
            }
        };

        Context.Regions.AddRange(regions);
        Context.SaveChanges();
    }

    [TestMethod]
    public async Task CanAddCountry()
    {
        //-- arrange
        var service = new CoreDataService(Context);

        var userId = "133BC82D-FDE2-4124-9207-CD3465511AEB";
        var region = await service.GetRegionById(1);

        var country = new Country
        {
            Name = "Canada",
            State = RecordState.Active,
            UserId = userId,
            Created = DateTime.Now,
            RegionId = region.Id
        };

        //-- act
        var results = await service.AddCountry(country);

        //-- assert
        Assert.IsTrue(results.Name == "Canada");
        Assert.IsTrue(results.UserId == "133BC82D-FDE2-4124-9207-CD3465511AEB");
        Assert.IsNotNull(results.Region);
    }

    [TestMethod]
    public async Task CanGetCountries()
    {
        //-- arrange
        var service = new CoreDataService(Context);

        var userId = "133BC82D-FDE2-4124-9207-CD3465511AEB";
        var region = service.GetRegionById(1);
        var names = new[] {"Canada", "Wales", "Japan", "Australia", "Hawaii", "Germany"};

        for (var x = 0; x < 5; x++)
        {
            await service.AddCountry(new Country
            {
                Name = names[x],
                State = RecordState.Active,
                UserId = userId,
                Created = DateTime.Now,
                RegionId = region.Id
            });
        }

        //-- act
        var results = await service.GetCountries();

        //-- assert
        Assert.IsNotNull(results);
        Assert.IsTrue(results.Count == 5);
    }

    [TestMethod]
    public async Task CanDeleteCountry()
    {
        //-- arrange
        var service = new CoreDataService(Context);

        var userId = "133BC82D-FDE2-4124-9207-CD3465511AEB";
        var region = service.GetRegionById(1);
        var names = new[] { "Canada", "Wales", "Japan", "Australia", "Hawaii", "Germany" };

        for (var x = 0; x < 5; x++)
        {
            await service.AddCountry(new Country
            {
                Name = names[x],
                State = RecordState.Active,
                UserId = userId,
                Created = DateTime.Now,
                RegionId = region.Id
            });
        }

        //-- act
        await service.DeleteCountry(id: 2, userId: Guid.NewGuid().ToString());

        var countries = await service.GetCountries();
        var country = await service.GetCountryById(2);

        //-- assert
        Assert.IsTrue(countries.Count != 5);
        Assert.IsNull(country);
    }
}

现在当我运行这个的时候，第三个测试失败了，因为它找不到正确的id，这对我来说有点奇怪。

我最初认为这是 MSTest 的问题，但在 xUnit 中也注意到了相同的行为。

public class CdiTestBase : IDisposable
{
    protected readonly CdiContext _context;

    public CdiTestBase()
    {
        var options = new DbContextOptionsBuilder<CdiContext>()
            .UseInMemoryDatabase(databaseName: $"{Guid.NewGuid()}")
            .Options;

        _context = new CdiContext(options);

        _context.Database.EnsureCreated();

        SeedRegions(_context);
    }

    public void Dispose()
    {
        _context.Database.EnsureDeleted();

        _context.Dispose();
    }

    private void SeedRegions(CdiContext context)
    {
        var regions = new List<Region>
        {
            new Region
            {
                Name = "Asia",
                State = RecordState.Active,
                Created = DateTime.Now,
                UserId = Guid.NewGuid().ToString()
            },

            new Region
            {
                Name = "Africa",
                State = RecordState.Active,
                Created = DateTime.Now,
                UserId = Guid.NewGuid().ToString()
            },

            new Region
            {
                Name = "South America",
                State = RecordState.Active,
                Created = DateTime.Now,
                UserId = Guid.NewGuid().ToString()
            }
        };

        context.Regions.AddRange(regions);
        context.SaveChanges();
    }
}

public class CountryTests : CdiTestBase
{
    [Fact]
    public async Task CanAddCountry()
    {
        //-- arrange
        var service = new CoreDataService(_context);

        var userId = "133BC82D-FDE2-4124-9207-CD3465511AEB";
        var region = await service.GetRegionById(1);

        var country = new Country
        {
            Name = "Canada",
            State = RecordState.Active,
            UserId = userId,
            Created = DateTime.Now,
            RegionId = region.Id
        };

        //-- act
        var results = await service.AddCountry(country);

        //-- assert
        Assert.True(results.Name == "Canada");
        Assert.True(results.UserId == "133BC82D-FDE2-4124-9207-CD3465511AEB");
        Assert.NotNull(results.Region);
    }

    [Fact]
    public async Task CanGetCountries()
    {
        //-- arrange
        var service = new CoreDataService(_context);

        var userId = "133BC82D-FDE2-4124-9207-CD3465511AEB";
        var region = service.GetRegionById(1);
        var names = new[] { "Canada", "Wales", "Japan", "Australia", "Hawaii", "Germany" };

        for (var x = 0; x < 5; x++)
        {
            await service.AddCountry(new Country
            {
                Name = names[x],
                State = RecordState.Active,
                UserId = userId,
                Created = DateTime.Now,
                RegionId = region.Id
            });
        }

        //-- act
        var results = await service.GetCountries();

        //-- assert
        Assert.NotNull(results);
        Assert.True(results.Count == 5);
    }

    [Fact]
    public async Task CanDeleteCountry()
    {
        //-- arrange
        var service = new CoreDataService(_context);

        var userId = "133BC82D-FDE2-4124-9207-CD3465511AEB";
        var region = service.GetRegionById(1);
        var names = new[] { "Canada", "Wales", "Japan", "Australia", "Hawaii", "Germany" };

        for (var x = 0; x < 5; x++)
        {
            await service.AddCountry(new Country
            {
                Name = names[x],
                State = RecordState.Active,
                UserId = userId,
                Created = DateTime.Now,
                RegionId = region.Id
            });
        }

        //-- act
        await service.DeleteCountry(id: 2, userId: Guid.NewGuid().ToString());

        var countries = await service.GetCountries();
        var country = await service.GetCountryById(2);

        //-- assert
        Assert.True(countries.Count != 5);
        Assert.Null(country);
    }
}

如果我运行同时进行所有测试，我总是会失败，但如果我运行每个测试单独进行，它们都会通过，这让我很困扰。

Answer 1

这是内存数据库自动生成密钥的一个已知问题，由 #6872 InMemory: Improve in-memory key generation 跟踪。

已在即将发布的 3.0 版本中修复 - Each property uses independent in-memory integer key generation:

Old behavior

Before EF Core 3.0, one shared value generator was used for all in-memory integer key properties.

New behavior

Starting with EF Core 3.0, each integer key property gets its own value generator when using the in-memory database. Also, if the database is deleted, then key generation is reset for all tables.

Why

This change was made to align in-memory key generation more closely to real database key generation and to improve the ability to isolate tests from each other when using the in-memory database.

除了更新测试代码以不依赖硬编码自动生成的值（无论如何这都不好）之外，您目前无能为力。

Entity Framework Core 2.2 在单元测试时拆卸后未重置

Entity Framework Core 2.2 not reseting after tear down while unit testing

c#

mstest

xunit

entity-framework-core