[Test]
public void EqualityOfRay()
{
    Assert.AreEqual(new Ray(Vector3D.UnitZ, Vector3D.One), new Ray(Vector3D.UnitZ, Vector3D.One));
    Assert.AreNotEqual(new Ray(Vector3D.UnitX, Vector3D.One),
        new Ray(Vector3D.UnitZ, Vector3D.One));
    Assert.AreNotEqual(new Ray(Vector3D.UnitZ, Vector3D.One),
        new Ray(Vector3D.UnitZ, Vector3D.One * 2));
}

[Test]
public void EqualityOfRay()
{
    Assert.AreEqual(new Ray(Vector3D.UnitZ, Vector3D.One), new Ray(Vector3D.UnitZ, Vector3D.One));
    Assert.AreNotEqual(new Ray(Vector3D.UnitX, Vector3D.One),
        new Ray(Vector3D.UnitZ, Vector3D.One));
    Assert.AreNotEqual(new Ray(Vector3D.UnitZ, Vector3D.One),
        new Ray(Vector3D.UnitZ, Vector3D.One * 2));
}

[Test]
public void CreateRay()
{
    var ray = new Ray(Vector3D.Zero, Vector3D.UnitZ);
    Assert.AreEqual(ray.Origin, Vector3D.Zero);
    Assert.AreEqual(ray.Direction, Vector3D.UnitZ);
}

[Test]
public void CreateRay()
{
    var ray = new Ray(Vector3D.Zero, Vector3D.UnitZ);
    Assert.AreEqual(ray.Origin, Vector3D.Zero);
    Assert.AreEqual(ray.Direction, Vector3D.UnitZ);
}

[Test]
public void CanConvertToStringAndBack()
{
    var ray = new Ray(Vector3D.UnitX, Vector3D.UnitY);
    var stringRay = ray.ToString();
    Assert.AreEqual("Ray({1, 0, 0},{0, 1, 0})", stringRay);
    var retrievedRay = new Ray(stringRay);
    Assert.AreEqual(ray.Origin, retrievedRay.Origin);
    Assert.AreEqual(ray.Direction, retrievedRay.Direction);
}

[Test]
public void CanConvertToStringAndBack()
{
    var ray = new Ray(Vector3D.UnitX, Vector3D.UnitY);
    var stringRay = ray.ToString();
    Assert.AreEqual("Ray({1, 0, 0},{0, 1, 0})", stringRay);
    var retrievedRay = new Ray(stringRay);
    Assert.AreEqual(ray.Origin, retrievedRay.Origin);
    Assert.AreEqual(ray.Direction, retrievedRay.Direction);
}

[Test]
public void ConvertingInvalidStringThrows()
{
    Assert.Throws<Ray.InvalidNumberOfStringComponents>(() => { new Ray("Ray({1, 0, 0})"); });

[Test]
public void ConvertingInvalidStringThrows()
{
    Assert.Throws<Ray.InvalidNumberOfStringComponents>(() => { new Ray("Ray({1, 0, 0})"); });