Overview

I am currently unit/integration testing my repository pattern with the in-memory database EF Core provides. I am on version 6.0.1 for the Microsoft.EntityFrameworkCore.InMemory nuget and using Visual Studio 2022. I am running into issues saving data to the database. Below I have included snippets of my code.

My data model:

public class Example : IExample

public Guid Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }

My base repository class:

public class Repository<T> : IRepository<T> where T : class

private readonly DbSet<T> _dbSet;
private readonly DbContext _db;

public Repository(DbContext db)
{
    _dbSet = db.Set<T>();
    _db = db;
}

public virtual async Task Add(T entity)
{
    await _dbSet.AddAsync(entity);
}

public virtual async Task<int> SaveAsync(CancellationToken token = default)
{
    return await _db.SaveChangesAsync(token);
}

My repository class:

public class ExampleRepo : Repository<Example>

public ExampleRepo(ExampleContext db) : base(db)
{
}

My DbContext Class

I can show my IEntityConfiguration class for the ExampleBuilder shown below if it is needed but I don't believe that to be the problem.

public class ExampleContext : DbContext

private readonly IHttpContextAccessor? _httpContextAccessor;

public ExampleContext(DbContextOptions<ExampleContext> options) : base(options)
{
    if (options == null) throw new ArgumentNullException(nameof(options));
}

public ExampleContext(DbContextOptions<ExampleContext> options, IHttpContextAccessor httpContextAccessor) 
    : base(options)
{
    if (options == null) throw new ArgumentNullException(nameof(options));
    _httpContextAccessor = httpContextAccessor ?? throw new ArgumentNullException(nameof(httpContextAccessor));
}

public DbSet<Example>? Examples { get; set; }

protected override void OnModelCreating(ModelBuilder builder)
{
    var assembly = Assembly.GetAssembly(typeof(ExampleBuilder));
    if (assembly is null)
    {
        throw new DataException("Could not find the assembly containing the designated model builder");
    }

    builder.ApplyConfigurationsFromAssembly(assembly);

    foreach (var entity in builder.Model.GetEntityTypes())
    {
        entity.SetSchema("dbo");
    }
}

public override Task<int> SaveChangesAsync(CancellationToken token = default)
{
    foreach (var entry in ChangeTracker.Entries()
                                       .Where(x => x.State is EntityState.Added or EntityState.Modified or EntityState.Deleted))
    {
        var user = _httpContextAccessor?.HttpContext?.User?.Identity?.Name ?? "User";
        entry.Property("ModifiedBy").CurrentValue = user;

        if (entry.State == EntityState.Added)
        {
            entry.Property("CreatedBy").CurrentValue = user;
        }

        if (entry.State != EntityState.Deleted) continue;

        entry.State                              = EntityState.Modified;
        entry.Property("IsActive").CurrentValue = false;
    }

    return base.SaveChangesAsync(token);
}

My DbContext factory method:

private ExampleContext GenerateDbContext()
{
    var options = new DbContextOptionsBuilder<ExampleContext>()
                  .UseInMemoryDatabase(Guid.NewGuid().ToString())
                  .Options;

    return new ExampleContext(options);
}

My unit/integration test utilizing xUnit and NET6.0

[Fact]
public async Task GetAllEntities_ShouldReturnEntities_WhenEntitiesExist()
{
    // Arrange

    // I used Bogus nuget for single source for generating valid models
    var entity = ExampleFaker.GetModelFaker()
                             .Generate();

    await using var context = GenerateDbContext();
    var             repo    = new ExampleRepo(context);

    await repo.Add(entity);
    var changes = await repo.SaveAsync();

    // Act

    // Consulted this link already. Bottom answer is most related
    //https://stackoverflow.com/questions/46184937/dbcontext-not-returning-local-objects
    var response = await repo.GetAll();

    // Assess
    TestOutputHelper.WriteLine($"Added entity to repository: {entity.ToJson()}");
    TestOutputHelper.WriteLine("Expected entities saved: 1");
    TestOutputHelper.WriteLine($"Actual entities saved: {changes}");
    TestOutputHelper.WriteLine($"Response: {response?.ToJson()}");

    // Assert
    Assert.Equal(1, changes);
    Assert.NotNull(response);
    Assert.NotEmpty(response);
    Assert.IsType<List<Example>>(response.ToList());
}

Analysis & Issue

The changes variable returns 1 so I interpret this as EF does not have any issue with my model as well as I would think it successfully saved my model in the in-memory database. However, during my GetAll retrieval, no data is returned. When I debug and look into the repository private members, it shows the DbSet is empty so it is not the GetAll method causing the issue either. Since this is also just within the scope of the unit test, I don't think my Program.cs configuration has anything to do with the issue I am seeing. I have been looking at this for quite a while and can't figure out the small detail I am probably missing for the life of me.

Thank you for your help in advance.