Testing with xUnit

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.

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.

Quick check: What does WebApplicationFactory<Program> provide?

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