Пример реализации бэкенда на C# — 12.2. Интеграционные тесты с TestServer

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

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

    [Fact]
    public async Task GetProduct_ReturnsOk()
    {
        var response = await _client.GetAsync("/api/products/1");
        response.EnsureSuccessStatusCode();
        var content = await response.Content.ReadAsStringAsync();
        Assert.Contains("Тест", content);
    }
}