Tag Archives: DbContextOptionsBuilder

Manually Adding DbContext for an Integration Test

In EF Core, there is an extension method that allows you to add a DBContext, called AddDBContext. This is a really useful method, however, in some cases, you may find that it doesn’t work for you. Specifically, if you’re trying to inject a DBContext to use for unit testing, it doesn’t allow you to access the DBContext that you register.

Take the following code:

services.AddDbContext<MyDbContext>(options =>
                options.UseSqlServer());
         

I’ve previously written about using UseInMemoryDatabase. However, this article covered unit tests only – that is, you are able to instantiate a version of the DBContext in the unit test, and use that.

As a reminder of the linked article, if you were to try to write a test that included that DBContext, you might want to use an in memory database; you might, therefore, build up a DBContextOptions like this:

var options = new DbContextOptionsBuilder<MyDbContext>()
                .UseInMemoryDatabase(Guid.NewGuid().ToString())
                .EnableSensitiveDataLogging()
                .Options;
var context = new MyDbContext(options);

But in a scenario where you’re writing an integration test, you may need to register this with the IoC. Unfortunately, in this case, AddDbContext can stand in your way. The alternative is that you can simply register the DbContext yourself:

var options = new DbContextOptionsBuilder<MyDbContext>()
                .UseInMemoryDatabase(Guid.NewGuid().ToString())
                .EnableSensitiveDataLogging()
                .Options;
var context = new MyDbContext(options);
AddMyData(context);
services.AddScoped<MyDbContext>(_ => context);

AddMyData just adds some data into your database; for example:

private void AddTestUsers(MyDbContext context)
{            
    MyData data = new MyData()
    {
        value1 = "test",
        value2 = "1"                
    };
    context.MyData.Add(subject);
    context.SaveChanges();
}

This allows you to register your own, in memory, DbContext in your IoC.

Short Walks – System.InvalidOperationException: ‘The seed entity for entity type ‘MyEntity’ cannot be added because another seed entity with the same key value for {‘Id’} has already been added. Consider using ‘DbContextOptionsBuilder.EnableSensitiveDataLogging’ to see the conflicting key values.’

I got this error recently while playing with EF Core 2. There’s very little on Google about it; although it’s not a hugely difficult problem to solve, if I ever get it again, I can just Google it !

The error:

System.InvalidOperationException: ‘The seed entity for entity type ‘MyEntity’ cannot be added because another seed entity with the same key value for {‘Id’} has already been added. Consider using ‘DbContextOptionsBuilder.EnableSensitiveDataLogging’ to see the conflicting key values.’

If effectively cause by a conflict in the primary key; and it gives you the first step towards solving it in the error (in OnModelCreating):

var options =
    new DbContextOptionsBuilder<ApplicationDbContext>()
         .UseSqlServer(configuration.GetConnectionString("DefaultConnection"))
         .EnableSensitiveDataLogging()
         .Options;

Now it says:

System.InvalidOperationException: ‘The seed entity for entity type ‘MyEntity’ cannot be added because another seed entity with the key value ‘Id:1′ has already been added.’

In my particular case, I’d been playing around with adding some seed data, and had left this in (OnModelCreating):

modelBuilder.Entity<MyEntity>().HasData(new Data.MyEntity()
{
    Id = 1,
    Name = "Test",
    CreatedDate = new DateTime(2018, 07, 03),
    UpdatedDate = new DateTime(2018, 07, 03)
});