MsTest - Mocking a DbContext with DbContextOption and configuration - entity-framework

Question

I have 2 project, Data and Data.test, I use ef core and .net core for both of them, for Data project I have ExpenseDb like this:
public class ExpenseDb: DbContext
{
private IConfigurationRoot _config;
public ExpenseDb(DbContextOptions<ExpenseDb> options, IConfigurationRoot config) : base(options)
{
_config = config;
}
public DbSet<Account> Accounts { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
base.OnConfiguring(optionsBuilder);
optionsBuilder.UseSqlServer(_config["Data:ConnectionString"]);
}
}
And I have a repository for Account like this:
private ExpenseDb _db;
public AccountRepository(ExpenseDb db)
{
_db = db;
}
public IEnumerable<Account> All(Guid userId)
{
return (_db.Accounts.AsNoTracking().Where(a => a.UserId == userId).ToList());
}
I use ms IOC for injectiong dependencies like this :
public Startup(IHostingEnvironment env)
{
var builder = new ConfigurationBuilder()
.SetBasePath(env.ContentRootPath)
.AddJsonFile("appsettings.json");
_config = builder.Build();
}
IConfigurationRoot _config;
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton(_config);
services.AddDbContext<ExpenseDb>(ServiceLifetime.Scoped);
}
These all are in my Data project, and for Data.Test I would like to test All method, I realized I must Mock my ExpenseDb so I got Moq from Nuget Package and now I have test class like this :
[TestClass]
public class AccountRepositoryTest
{
private readonly Mock<ExpenseDb> _dbMock = new Mock<ExpenseDb>();
private readonly AccountRepository _repo;
public AccountRepositoryTest()
{
_repo = new AccountRepository(_dbMock.Object);
}
[TestMethod]
public void AllForInvalidUser()
{
var fakeaccount = new Account() { Name="cat2",OpenDate=DateTime.Now,StartBalance=100};
Mock < DbSet < Account >> acMock = DbSetMock.Create(fakeaccount);
var results = _repo.All(Guid.Parse("cf15c6c9-f688-47ee-892e-297e530be053"));
Assert.IsNotNull(results);
}
}
Obviously my test is failed, because I must pass config and options to my ExpenseDb somehow, but I don't know How?!
I searched and I found out all answer are saying "You must have an inteface for your service" but i don't want to create an unnecessary interface.

Answer 1

Since DbContextOptions and config are not being used in the actual test code. You could create a constructor in your db context marked as protected to allow the instantiation of the ExpenseDb object without any params.