CleanArchitecture-template/.brain/.agent/skills/custom-skills/GenerateTest/IntegrationTest.md

name, description

name	description
GenerateIntegrationTest	Guide to creating Integration Tests (end-to-end) using WebApplicationFactory and Testcontainers.

GenerateIntegrationTest Skill

When a user requests to create an Integration Test to verify API endpoints from start to finish, you need to generate the code according to the following guidelines:

Purpose

• Test whether the assembled components work correctly together.
• Flow: Client calls API -> Middleware -> Controller -> CQRS Handler/Service -> Read/Write to a real Database.

Implementation Guide

1. Setup WebApplicationFactory:

   • Automatically setup WebApplicationFactory<Program> (to create an in-memory test server in .NET).
   • Override application configurations if necessary (e.g., changing the ConnectionString to point to a test container).

2. Setup Testcontainers (Real Database):

   • Use the Testcontainers library (or similar configuration) to automatically spin up a Docker container containing a real Database (e.g., PostgreSQL, SQL Server).
   • Ensure this database container starts before the tests run and is automatically disposed of after the tests complete. Avoid using in-memory SQLite because it often causes minor bugs and does not accurately mimic a production database.

3. Write API Test Scenarios (Arrange - Act - Assert):

   • Create an HttpClient object from WebApplicationFactory.CreateClient().
   • Arrange: Prepare payload data as JSON objects or prepopulate database records for GET/PUT/DELETE APIs.
   • Act: Call the corresponding API endpoint directly via code. E.g.: await client.PostAsJsonAsync("/api/v1/samples", payload);.
   • Assert: Verify the returned results:
     • Check HTTP Status: is it 200 OK or 400 Bad Request?
     • Deserialize the response body to check the exact object data.
     • (Optional) Query the database container directly to confirm the record was actually created/updated.

Output File Format

• Path: Placed in the corresponding test project, such as tests/MyNewProjectName.IntegrationTests/Controllers/....
• File Name: [ControllerName]Tests.cs (e.g., OrdersControllerTests.cs).