mocking-inprocess-dotnet

name

mocking-inprocess-dotnet

description

Use when the mocking-strategy-roster resolved (inprocess, .NET) — the override mocking strategy that replaces a downstream dependency with an in-process test double (FakeItEasy, NSubstitute, or Moq) instead of a Microcks container. Provides the concrete double registration swapped into the WebApplicationFactory DI. Emits mock wiring only; the business TDD cycle stays with the software-engineer lead.

Mocking — In-process x .NET adapter (override)

Concrete recipe that mocks a downstream dependency the SUT calls, using an in-process test double registered in the WebApplicationFactory DI, instead of a Microcks container. Selected when the operator overrides the Microcks default.

Loaded ONLY when mocking-strategy-roster resolved (inprocess, .NET). The roster also passes the chosen library: fakeiteasy | nsubstitute | moq. When no specific library is named, the Library table below is ordered by priority (top = highest): pick the first row whose package is already present in the test project; if none is present, take the top row.

Boundary: mock wiring + integration-test scaffold only. No business TDD, no Object Calisthenics enforcement, no provider contract verification. The software-engineer lead integrates this into its own TDD loop.

Library packages (table order = priority, top = highest)

Priority	Library	NuGet	Double creation
1	fakeiteasy	FakeItEasy	A.Fake<I{Downstream}Client>()
2	nsubstitute	NSubstitute	Substitute.For<I{Downstream}Client>()
3	moq	Moq	new Mock<I{Downstream}Client>() (use .Object for the instance)

Recipe — register an in-process double in the test host

public class {Sut}ApiFactory : WebApplicationFactory<Program>
{
    public I{Downstream}Client DownstreamDouble { get; } =
        // Create via the resolved library's "Double creation" column above.
        CreateDouble();

    protected override void ConfigureWebHost(IWebHostBuilder builder)
    {
        builder.ConfigureServices(services =>
        {
            // Replace the real downstream client registration with the double.
            services.RemoveAll<I{Downstream}Client>();
            services.AddSingleton(DownstreamDouble);
        });
    }
}

The test arranges behaviour on DownstreamDouble using the resolved library's API (Mock.Setup / A.CallTo / client.Method(...).Returns(...)).

Structured result back to the lead

Return, do not commit:

strategy: inprocess
stack: dotnet
library: fakeiteasy | nsubstitute | moq
files:
  - test/{Sut}.IntegrationTests/{Sut}ApiFactory.cs
testCommand: <resolved via resolving-stack-commands>
notes: in-process double for I{Downstream}Client swapped into the test host DI

Rules

• Double the DOWNSTREAM client interface, never the SUT's own domain.
• This is an INTEGRATION-test double at the HTTP boundary — not a Domain/Application unit mock (those remain forbidden in the core per craft-discipline).
• Use resolving-stack-commands for the test command — never hardcode dotnet test.