using System;

public class Program

{

    public static void Main()

    {

        var january2018 = new DateRange("2018-01-01", "2018-01-31");

        Debug.Assert(false == january2018.Overlaps(new DateRange("2018-02-01", "2018-02-28")));  // after

        Debug.Assert(true == january2018.Overlaps(new DateRange("2018-01-15", "2018-02-28")));   // starts in, finishes out

        Debug.Assert(true == january2018.Overlaps(new DateRange("2018-01-15", "2018-01-20")));   // inside

        Debug.Assert(true == january2018.Overlaps(new DateRange("2018-01-01", "2018-01-31")));   // same

        Debug.Assert(false == january2018.Overlaps(new DateRange("2017-01-15", "2017-01-20")));  // before

        Debug.Assert(true == january2018.Overlaps(new DateRange("2017-12-15", "2018-01-20")));   // starts before, finishes in

        Debug.Assert(true == january2018.Overlaps(new DateRange("2017-12-15", "2018-02-28")));   // starts before, finishes after

        Console.WriteLine("Success");

    }

}

​

public class DateRange

{

    public bool Overlaps(DateRange range2)

    {

        Console.WriteLine("Checking: {0} and {1}", this.ToString(), range2.ToString());

        throw new NotImplementedException();

    }

    public DateRange(string start, string end) : this(DateTime.Parse(start), DateTime.Parse(end)) { }

    public DateRange(DateTime start, DateTime end)

    {

        Start = start;

        End = end;

    }

    public DateTime Start { get; set; }

    public DateTime End { get; set; }

    public override string ToString()

    {

        return ToString("d");

    }

    public string ToString(string format)

    {

        return string.Format("{0} - {1}", Start.ToString(format), End.ToString(format));

    }

}

​

public static class Debug

{

    public static void Assert(bool value)

    {

        if (!value)

        {

            throw new Exception("Assertion failed");

        }

    }

}