In the post of the series we saw how to use SQL Server on Docker as the database for our integration tests during local development.

In this article you will know how to optimize integration testing by running tests incrementally. Example is using .Net Core with Bazel, but the concepts discussed in this article are language agnostic.

When I first started playing with API testing in .NET Core 3, I wanted to have a quick In Memory API test that takes snapshots. In this article, I am going to describe a way how to do it easily so even you can do it in your project. If you are not familiar with the snapshot testing and why you should care, it will be explained below.

For certain types of code, unit testing works brilliantly, flows naturally, and significantly enhances the quality of the resulting code. But for other types of code, writing unit tests consumes a huge amount of effort, doesn’t meaningfully aid design or reduce defects at all, and makes the codebase harder to work with by being a barrier to refactoring or enhancement.

It’s pretty simple as there’ great support from Microsoft.AspNetCore.Mvc.Testing and Microsoft.AspNetCore.TestHost nuget packages. I’ve used XUnit together with packages mentioned. In my opinion it works best due to ClassFixtures and Collections that XUnit is providing.

This time instead of manual testing, we will make automated integration tests that make testing the API's behaviour easy. They can also confirm the API conforms to its contract. But the authentication requirement presents some challenges.

If you want to run an integration test for your ASP.NET Core app without also testing lots of external dependencies like databases and the like, then the lengthy official ‘Integration tests in ASP.NET Core‘ documentation shows how you can use stubs to replace code that talks to a database or some other external service. If you want to use mocks, this is where you run out of guidance and runway.

This blog post shows you how to create fake users for ASP.NET Core integration tests and write effective extension methods to keep integration tests shorter.