// Iteration 0 (time limit: 15 minutes)

//-----------------------------------------------------------------------------------------

//

// Instructions:

//

// Let's do a code review. Please review the following program.

// 

// Feel free to ask questions, run the program as many times as you want, make changes, 

// test them out, add comments, and use any help you have available.

//

// Note any problems you would like to point out or discuss further, keeping in mind the 

// following criteria:

//  * Correctness

//  * Completeness

//  * Compactness

//  * Consistency

//  * Style

//  * Other?

//-----------------------------------------------------------------------------------------

​

using System;

public class Program

{

    public static void Main()

    {

        StringGatewayTests.IsNullOrWhiteSpace_NullValue_ReturnsTrue();

        StringGatewayTests.IsNullOrWhiteSpace_EmptyValue_ReturnsTrue();

        StringGatewayTests.IsNullOrWhiteSpace_AllWhitespaceValue_ReturnsTrue();

        StringGatewayTests.IsInterned_NullValue_ReturnsFalse();

    }

}

​

public static class StringGateway

{

    public static bool IsNullOrWhiteSpace(this string str) => string.IsNullOrWhiteSpace(str);

​

    public static bool IsInterned(this string str)

    {

        if (str is not null && string.IsInterned(str) is string interned)

        {

            return true;

        }

        else

        {

            return false;

        }

    }

    // TODO: This does not work (yet?)

    //public static string? IsInternedV2(this string str) => string.IsInterned(str);

}

​

public class StringGatewayTests

{

    private static string Value;

    public static void IsNullOrWhiteSpace_NullValue_ReturnsTrue()

    {

        Value = null;

        bool Result = Value.IsNullOrWhiteSpace();

        System.Diagnostics.Debug.Assert(Result == true);

        "OK".Dump();

    }

​

    public static void IsNullOrWhiteSpace_EmptyValue_ReturnsTrue()

    {

        Value = string.Empty;

        bool Result = Value.IsNullOrWhiteSpace();

        System.Diagnostics.Debug.Assert(Result == true);

        "OK".Dump();

    }

​

    public static void IsNullOrWhiteSpace_AllWhitespaceValue_ReturnsTrue()

    {

        Value = "   \r\n \t";

        bool Result = Value.IsNullOrWhiteSpace();

        System.Diagnostics.Debug.Assert(Result == true);

        "OK".Dump();

    }

​

    public static void IsInterned_NullValue_ReturnsFalse()

    {

        Value = null;

        bool Result = Value.IsInterned();

        System.Diagnostics.Debug.Assert(Result == false);

        "OK".Dump();

    }

​

    public static void IsInterned_StringLiteralValue_ReturnsTrue()

    {

        Value = "This is a test.";

        bool Result = Value.IsInterned();

        System.Diagnostics.Debug.Assert(Result == true);

        "OK".Dump();

    }

​

    // TODO: This does not work (yet?)

    //public static void IsInternedV2_NullValue_ReturnsTrue()

    //{

    //  Value = "This is a test.";

    //  string? Result = value.IsInternedV2();

    //  System.Diagnostics.Debug.Assert(Result != null);

    //  "OK".Dump();

    //}

}

​