Scaffold Test Files

Given a .NET source file, automatically create matching unit test and integration test directories and files under the test project, following the project's existing conventions and clean DI patterns.

When to Use

• User selects a source file and wants test files created for it
• User asks to "set up tests for this file" or "create test structure for X"
• Starting a new coverage session where no test file exists yet
• Adding integration test support alongside existing unit tests

When Not to Use

• Test files already exist for the source file — use improve-test-coverage instead
• User only wants to run existing tests — use run-coverage
• User wants to inspect coverage gaps — use analyze-coverage-gaps
• Non-.NET project

Inputs

Workflow

Step 1: Analyze source file

Read the source file to extract:

• Namespace (e.g., MainProject.Subproject.Services)
• Class name (e.g., ExampleService)
• Constructor parameters — all injected interfaces (e.g., IRepository, ILogger<T>)
• Public methods — names and signatures to create test stubs for

Step 2: Detect test project structure

Scan the solution for test projects:

glob **/*Test*.csproj
glob **/*Tests*.csproj

Determine the layout:

• Separate projects: UnitTests.csproj and IntegrationTests.csproj exist separately → use each
• Single project: One test .csproj with folders like Unit/ and Integration/ inside → use subfolders
• No test project: Inform the user they need to create one first

Step 3: Mirror directory structure

Map the source path to test paths by mirroring the subfolder structure:

Source: MainProject/Subproject/Services/ExampleService.cs

Separate projects:

• TestProject.UnitTests/Subproject/Services/ExampleServiceTests.cs
• TestProject.IntegrationTests/Subproject/Services/ExampleServiceIntegrationTests.cs

Single project:

• TestProject/UnitTests/Subproject/Services/ExampleServiceTests.cs
• TestProject/IntegrationTests/Subproject/Services/ExampleServiceIntegrationTests.cs

Create any missing directories.

Step 4: Read project conventions

Before generating boilerplate, read 2–3 existing test files in the test project to learn:

• Using statements — which namespaces are imported
• Mock framework — Moq (Mock<T>), NSubstitute (Substitute.For<T>), or FakeItEasy
• Base class — whether tests inherit from a base test class
• Attribute style — [TestFixture], [SetUp], [Test] (NUnit)
• Naming convention — MethodName_Condition_Result or other patterns
• DI setup patterns — how ServiceCollection or WebApplicationFactory is configured

If no existing test files, use NUnit defaults with clean DI patterns.

Step 5: Read context-specific rules

Based on test type being generated:

• Unit tests → read references/unit.md for rules
• Integration tests → read references/integration.md for rules

Apply these rules when generating the boilerplate.

Step 6: Generate unit test file

Create the unit test file with boilerplate matching the project's conventions:

• Namespace mirroring source namespace
• [TestFixture] class
• Constructor or [SetUp] creating mocks for all injected interfaces
• Instantiating the class under test with mocked dependencies
• Empty test method stubs for each public method (no assertions — those come from improve-test-coverage)

Step 7: Generate integration test file

Create the integration test file with clean DI + in-memory infrastructure:

• Namespace mirroring source namespace
• [TestFixture] class
• [SetUp] building a real ServiceCollection with:
• In-memory database (UseInMemoryDatabase) if EF Core DbContext is used
• Real service registrations from the project's DI composition root
• Only external services mocked (HTTP clients, third-party APIs)
• ServiceProvider built and class under test resolved from DI
• Empty test method stubs for each public method

Step 8: Restore NuGet packages

CRITICAL: If you created a new test project or added NuGet packages (Moq, NUnit, Microsoft.NET.Test.Sdk, etc.), you MUST run dotnet restore before any test execution. When calling RunTestsWithCoverage after scaffolding, set forceRestore=true on the first run.

Step 9: Update target .gitignore

If the target repository's .gitignore does not already contain .mcp-coverage/, add it. This directory holds session-scoped coverage state files generated by the MCP server.

Step 10: Report created files

List all created directories and files with their paths.

Validation

• [ ] Source file was read and class/constructor/methods extracted
• [ ] Test project structure detected correctly (separate vs unified)
• [ ] Directory structure mirrors the source path
• [ ] Unit test file follows project's existing mock framework and conventions
• [ ] Integration test file uses in-memory infrastructure with real DI
• [ ] No hardcoded templates — boilerplate matches what's already in the project
• [ ] Created files compile (no missing usings or references)

Common Pitfalls