Blog.TestContext.WithArg.cs

public class MyTestContext
{
    private readonly Arg<string> _tag = Arg.String.Default(Gen.Tag.Generate());
    private readonly Arg<DateTimeOffset> _before = Arg.Date.Ignore();

    public static MyTestContext Given()
    {
        return new MyTestContext();
    }

    public void WhenTag(string tag)
    {
        _tag.TryOverwrite(tag);
        _tag.PreserveValue();
    }

    public void WhenRequest(string tag = null, DateTimeOffset? before = null)
    {
        _tag.TryOverwrite(tag);
        _before.TryOverwrite(before);
    }

    public async Task ShouldRespondWithAsync(Func<HttpResponseMessage, Task> assertionAsync)
    {
        var request = new HttpRequestMessage(HttpMethod.Get, $"http://localhost:1234/api/app?tag={_tag}&before={_before}");

        // Ignore this; out of scope.
    }
}