ActionFluentAssertions.cs

/// <summary>
/// Note that if this is the end of your assertion chain then append () or .Invoke() to the end
/// </summary>
/// <param name="action"></param>
/// <param name="time"></param>
/// <param name="precision"></param>
/// <returns></returns>
public static Action ShouldTakeCloseTo(this Action action, TimeSpan time)
{
    return () =>
    {
        var startTime = DateTime.Now;
        action();
        TimeSpan executionTimespan = DateTime.Now - startTime;
        executionTimespan.Should().BeCloseTo(time);
    };
}

public static Action And(this Action action)
{
    return action;
}