如何为每个测试创建单独的内存数据库？

Question

我正在 .NET Core 3.0 上使用 xunit 编写测试，但内存数据库有问题。我需要为每个测试创建一个单独的数据库，但现在我创建一个会导致问题的数据库，但我不知道如何为每个测试创建一个新数据库。

public class AccountAdminTest : IClassFixture<CustomWebApplicationFactory<Startup>>
{
    private readonly HttpClient _client;
    private IServiceScopeFactory scopeFactory;
    private readonly CustomWebApplicationFactory<Startup> _factory;
    private ApplicationDbContext _context;

    public AccountAdminTest(CustomWebApplicationFactory<Startup> factory)
    {
        _factory = factory;
        _client = _factory.CreateClient(new WebApplicationFactoryClientOptions
        {
            AllowAutoRedirect = true,
            BaseAddress = new Uri("https://localhost:44444")
        });

        scopeFactory = _factory.Services.GetService<IServiceScopeFactory>();
        var scope = scopeFactory.CreateScope();
        _context = scope.ServiceProvider.GetService<ApplicationDbContext>();
    }
}

public class CustomWebApplicationFactory<TStartup> : WebApplicationFactory<TStartup> where TStartup : class
{
    protected override void ConfigureWebHost(IWebHostBuilder builder)
    {
        builder.ConfigureTestServices(services =>
        {
            var descriptor = services.SingleOrDefault(
                d => d.ServiceType ==
                    typeof(DbContextOptions<ApplicationDbContext>));

            if (descriptor != null)
            {
                services.Remove(descriptor);
            }

            services.AddDbContext<ApplicationDbContext>((options, context) =>
            {
                context.UseInMemoryDatabase("IdentityDatabase");
            });
        });
    }
}

---

现在看起来像这样，但仍然不起作用。当我更改 AddDbContext 的生命周期时，它不会改变任何内容。

public class AccountAdminTest : IDisposable
{
    public AccountAdminTest(ITestOutputHelper output)
    {
        this.output = output;

        _factory = new CustomWebApplicationFactory<Startup>();

        _client = _factory.CreateClient(new WebApplicationFactoryClientOptions
        {
            AllowAutoRedirect = true,
            BaseAddress = new Uri("https://localhost:44444")
        });

        scopeFactory = _factory.Services.GetService<IServiceScopeFactory>();
        _scope = scopeFactory.CreateScope();
        _context = _scope.ServiceProvider.GetService<ApplicationDbContext>();


        var _user = User.getAppAdmin();
        _context.Add(_user);
        _context.SaveChanges(); //Here i got error on secound test. It says "An item with the same key has already been added"
    }

    public void Dispose()
    {
        _scope.Dispose();
        _factory.Dispose();
        _context.Dispose();
        _client.Dispose();
    }

---

使用 Guid 作为数据库名称时无法获取令牌。它说用户名/密码无效。我使用 IdentityServer 进行身份验证

public async Task<string> GetAccessToken(string userName, string password, string clientId, string scope)
        {
            var disco = await _client.GetDiscoveryDocumentAsync("https://localhost:44444");
            if (!String.IsNullOrEmpty(disco.Error))
            {
                throw new Exception(disco.Error);
            }
            var response = await _client.RequestPasswordTokenAsync(new PasswordTokenRequest
            {
                Address = disco.TokenEndpoint,
                ClientId = clientId,
                Scope = scope,
                UserName = userName,
                Password = password,
            });
            return response.AccessToken;
        }

Answer 1

您需要更改的只是此处的代码：

services.AddDbContext<ApplicationDbContext>((options, context) =>
{
    context.UseInMemoryDatabase("IdentityDatabase");
});

不要使用常量值"IdentityDatabase"，而是使用以下内容Guid.NewGuid().ToString()：

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

然后，每次获取上下文时，它将使用新的内存数据库。