C# Interview Question #181

What is integration testing in ASP.NET Core?

Testing, Security, APIs & Reliability Senior Advanced

Quick Interview Answer

Integration testing verifies that multiple application components work together correctly. Unlike a unit test, it may exercise routing, middleware, model binding, dependency injection, authentication, database access, and HTTP responses together.

Detailed Explanation

ASP.NET Core provides WebApplicationFactory<TEntryPoint> through Microsoft.AspNetCore.Mvc.Testing for hosting an application in a test environment.

Integration tests are valuable for critical API endpoints and infrastructure boundaries because they can catch configuration and wiring problems that isolated unit tests cannot detect.

Code Example

public class ProductsApiTests :
    IClassFixture<WebApplicationFactory<Program>>
{
    private readonly HttpClient _client;

    public ProductsApiTests(
        WebApplicationFactory<Program> factory)
    {
        _client = factory.CreateClient();
    }

    [Fact]
    public async Task GetProducts_ReturnsSuccess()
    {
        var response =
            await _client.GetAsync("/api/products");

        response.EnsureSuccessStatusCode();
    }
}