Question

I’m making unit-tests for this class, a triangle class that takes the sides and determines if the triangle is scalene, isosceles or equilateral.

public struct Point
{
    public int x, y;

    public Point(int a, int b)
    {
        x = a;
        y = b;
    }
}

public class Triangle
{
    double[] sides;

    public Triangle(double a, double b, double c)
    {
        if ((a <= 0) || (b <= 0) || (c <= 0))
        {
            throw new ArgumentException(" ");
        }
        sides = new double[] { a, b, c };
    }

    public Triangle(double[] s)
    {
        sides = new double[s.Length];
        for (int i = 0; i < s.Length; i++)
            sides[i] = s[i];
    }

    public Triangle(Point a, Point b, Point c)
    {
        sides = new double[3];
        sides[0] = Math.Sqrt(Math.Pow((double)(b.x - a.x), 2.0) + Math.Pow((double)(b.y - a.y), 2.0));
        sides[1] = Math.Sqrt(Math.Pow((double)(b.x - c.x), 2.0) + Math.Pow((double)(b.x - a.x), 2.0));
        sides[2] = Math.Sqrt(Math.Pow((double)(c.x - a.x), 2.0) + Math.Pow((double)(c.x - a.x), 2.0));
    }

    public Triangle(Point[] s)
    {
        sides = new double[s.Length];
        sides[0] = Math.Sqrt(Math.Pow((double)(s[1].x - s[0].x), 2.0) + Math.Pow((double)(s[1].y - s[0].y), 2.0));
        sides[1] = Math.Sqrt(Math.Pow((double)(s[1].x - s[2].x), 2.0) + Math.Pow((double)(s[1].x - s[2].x), 2.0));
        sides[2] = Math.Sqrt(Math.Pow((double)(s[2].x - s[0].x), 2.0) + Math.Pow((double)(s[2].x - s[0].x), 2.0));
    }

    private int uniqueSides()
    {
        return sides.Distinct<double>().Count();
    }

    public bool isScalene()
    {
        if (uniqueSides() == 1)
            return true;
        return false;
    }

    public bool isEquilateral()
    {
        if (uniqueSides() == 3)
            return true;
        return false;
    }

    public bool isIsosceles()
    {
        if (uniqueSides() == 2)
            return true;
        return false;
    }
}

}

The isScaleneTest is failing, and I can’t figure out why?

[TestMethod()]
    public void isScaleneTest()
    {
        Triangle target = new Triangle(1.2, 2.1, 7.1);
        Assert.IsTrue(target.isScalene());
    }

I also have problem figuring out how to test the other methods. isEquilateral and isIsosceles is tested and passes, but I can’t get any other test to pass. Any ideas? Is there any point to testing the constructor? Thanks for help.

Answer 1

A scalene triangle has three sides that are all unequal. The code for isScalene should be:

public bool isScalene()
{
    if (uniqueSides() == 3)
        return true;
    return false;
}

Also, the code for is isEquilateral is wrong. An equilateral triangle has three equal sides, so the return for uniqueSides for an equilateral triangle should be 1 vice 3.