using System;

using System.Collections.Generic;

using System.Linq;

​

/*

Create class or classes to calculate area of 

triangle S = 0.5 (a · h) and circle S = π r^2.

Use of TDD is prefferable

Classes should follow SOLID and other ODD principles

​

*/

public interface IFigure

{

    double GetArea();

}

​

public class Circle : IFigure

{

    private const double pi = 3.14;

​

    private double _radius;

    public double Radius{get {return _radius;}}

    public Circle(double radius)

    {

        _radius = radius;

    }

    public double GetArea()

    {

    return pi * _radius * _radius;

    }

}

public class Triangle : IFigure

{

    private double _side;

    public double Side {get { return _side;}}

    private double _height;

    public double Height {get {return _height;}}

    public Triangle(double side, double height)

    {

        _side = side;

        _height = height;

    }

    public double GetArea()

    {

    return 0.5 * _side * _height;

    }

}

​

public class TestRunner

{

    public static void Main()

    {

        ExecuteTests();

        Console.ReadLine();

    }

​

    public static void ExecuteTests()

    {

        var tests = new TestsFixture();

        var failedTests = new List<string>();

        // using reflection, run every test method and record the names of those methods that fail

        foreach (var m in typeof(TestsFixture).GetMethods().Where(m => m.DeclaringType != typeof(object)))

        {

            if (Convert.ToBoolean(m.Invoke(tests, null)) != true)

                failedTests.Add(m.Name);

        }

​

        // display all the failed tests, or a message that everything passed

        if (failedTests.Any())

            Console.WriteLine("Failed Tests: \r\n\r\n{0}", string.Join("\r\n", failedTests));

        else

            Console.WriteLine("All tests passed!");

    }

}

​

public class TestsFixture

{

    public bool GetCircleAreaInt()

    {

        IFigure circle = new Circle(1);

        return circle.GetArea().Equals(3.14);

    }

    public bool GetCircleAreaDouble()

    {

        IFigure circle = new Circle(1.5);

        return Math.Abs(circle.GetArea() - 7.065) < 0.0000001;

    }

    public bool GetCTriangleAreaInt()

    {

        IFigure triangle = new Triangle(1, 2);

        return triangle.GetArea().Equals(1);

    }

    public bool GetCTriangleAreaDouble()

    {

        IFigure triangle = new Triangle(1.5, 2.5);

        return triangle.GetArea().Equals(1.875);

    }   

}