public void Constructor_with_rotation_axis_and_angle()
{
Vector3 rotationAxis = Vector3.ZAxis;
var angle = Constants.HALF_PI;
var quaternion = new Quaternion(rotationAxis, angle);
var halfSquarerootOfTwo = 0.5f * Functions.Sqrt(2);
quaternion.W.ShouldEqual(halfSquarerootOfTwo);
quaternion.X.ShouldEqual(0);
quaternion.Y.ShouldEqual(0);
quaternion.Z.ShouldEqual(halfSquarerootOfTwo);
}