# Testing with xUnit — .NET Core: Build, Test and Ship Web APIs

Source: https://www.geekswithgeeks.com/en/dotnet-core/sec-testing

> Write unit tests and an in-memory integration test using WebApplicationFactory.

## Two kinds of tests

**Unit tests** check one class with fakes for its dependencies and run in milliseconds. **Integration tests** start the real app pipeline in memory with `WebApplicationFactory<Program>` and send HTTP requests to it. Use many of the first and a few of the second.

## A unit test and an API test

Add `public partial class Program { }` at the end of `Program.cs` so the test project can see it. Run everything with `dotnet test`.

```csharp
public class GreeterTests
{
    [Fact]
    public void Greet_ReturnsGreeting()
        => Assert.Equal("Hello, Asha!", new Greeter().Greet("Asha"));
}

public class ApiTests(WebApplicationFactory<Program> factory)
    : IClassFixture<WebApplicationFactory<Program>>
{
    [Fact]
    public async Task Root_ReturnsOk()
    {
        var res = await factory.CreateClient().GetAsync("/");
        Assert.Equal(HttpStatusCode.OK, res.StatusCode);
    }
}
```

## Test behaviour, not wiring

Tests that mirror the implementation line by line break on every refactor. Assert on results a caller can see: status codes, response bodies and saved data.

**Quiz:** What does WebApplicationFactory<Program> provide?

- [x] An in-memory test server running your app
- [ ] A production load balancer
- [ ] A database schema generator
- [ ] A code formatter

*Answer:* An in-memory test server running your app. It hosts your real pipeline in the test process so you can call it with an `HttpClient`.