controllertests.cs

public class ControllerTests : IClassFixture<Fixture<Startup>>
{
    private readonly Fixture<Startup> _fixture;

    public ControllerTests(Fixture<Startup> fixture) => _fixture = fixture;

    [Fact]
    public async Task ReturnsOrganizationRepositories()
    {
        // Arrange
        using var _ = _fixture.InterceptorOptions.BeginScope();
        new HttpRequestInterceptionBuilder()
            .Requests()
            .ForHttps()
            .ForHost("api.github.com")
            .ForPath("orgs/weyland-yutani/repos")
            .ForQuery("per_page=10")
            .Responds()
            .WithSystemTextJsonContent(new[] {new {id = 1, name = "foo"}, new {id = 2, name = "bar"}})
            .RegisterWith(_fixture.InterceptorOptions);

        // Act
        using var httpClient = _fixture.CreateClient();

        string json = await httpClient.GetStringAsync("api/repos");
        var actual = JsonConvert.DeserializeObject<string[]>(json);

        // Assert
        actual.ShouldBe(new[] {"bar", "foo"});
    }
}