public void testSkew() {
System.out.println("skew");
double ax = 2.0;
double ay = 3.0;
TransformationMatrix instance = new TransformationMatrix();
instance.skew(ax, ay);
TransformationMatrix instance2 = new TransformationMatrix();
instance2.getMatrix().getVy().setX(Math.tan(ay));
instance2.getMatrix().getVx().setY(Math.tan(ax));
assertEquals(instance, instance2);