MagicCSharp.Testing.Database

MagicCSharp.Testing.Database

Repository integration testing against a real PostgreSQL, via Testcontainers. One container for the whole suite, a database per test class, a fake clock and key generator already wired. Requires Docker.

Add it to the test project beside your data project — the one with the DALs and repositories. Split out from MagicCSharp.Testing on purpose: the fakes there have no heavy dependencies, and a project that only wants FakeTimeProvider should not pull in Testcontainers, xUnit and Npgsql.

dotnet add package MagicCSharp.Testing.Database

Why a real database

A repository is mostly translation — a filter into SQL, a row into an entity. The in-memory and SQLite providers translate differently from Postgres, so a test that passes against them proves the C# and not the query, which is the half that breaks. Enum-as-string columns, jsonb round-trips and timestamptz offset rules have no equivalent anywhere else.

MagicCSharp's own repository bases are tested this way — tests/MagicCSharp.Data.EntityFramework.Tests is fifty tests over a real Postgres, covering create, filter, update, delete, pagination, soft delete and the search column. It is the worked example of everything below.

Cost control

One container for the whole suite. One logical database per test class, so classes run in parallel without seeing each other's rows. Schema created once per database. Tables truncated between tests rather than recreated.

Use

[Trait("Category", "Integration")]
public class OrdersRepositoryTests : TestRepositoryBase<MagicShopContext>
{
    private OrdersEfRepository OrdersRepository =>
        new OrdersEfRepository(DbContextFactory, KeyGen, TimeProvider, NullLoggerFactory.Instance);

    [Fact]
    public async Task Create_assigns_created_and_updated_from_the_clock()
    {
        TimeProvider.SetUtcNow(new DateTimeOffset(2026, 3, 1, 0, 0, 0, TimeSpan.Zero));

        var order = await OrdersRepository.Create(new OrderEdit
        {
            CustomerId = 7,
            Total = 42.50m,
            Status = OrderStatus.Pending,
        });

        Assert.Equal(TimeProvider.GetUtcNow(), order.Created);
    }
}

TimeProvider is a FakeTimeProvider starting at a fixed instant (1 January 2026, UTC), KeyGen a FakeKeyGen derived from it, and DbContextFactory the pooled factory for your context — the same three things the repository takes in production. The clock only moves forward: set it in the test's constructor, then advance it.

Override ContainerImage to match production, or to get an extension — a context with a vector column needs pgvector/pgvector:pg17. Override InitializeDatabase to Database.MigrateAsync() when you want the test to prove the migrations produce a working schema, rather than building it from the model. ConfigureDataSource and ConfigureNpgsql take the same hooks as AddPostgresDbContextFactory, so a type plugin registered in production is registered here too.

Run without Docker by filtering: dotnet test --filter "Category!=Integration".

Related packages

• MagicCSharp.Testing — FakeTimeProvider, FakeKeyGen, SyncEventDispatcher, without Docker
• MagicCSharp.Data.EntityFramework — the repositories under test

The whole picture, and the optional repository layout: github.com/MagicDoorInc/MagicCSharp. MIT.