### Question:
Size { public Size minus(Size aSize) { return new Size(width - aSize.getWidth(), height - aSize.getHeight()); } Size();  Size(int width, int height); void setWidth(int width); void setHeight(int height); int getWidth(); int getHeight(); @Override String toString(); @Override boolean equals(Object o); @Override int hashCode(); Size minus(Size aSize); Size add(Size aSize); Size append(int width, int height); Size append(Size aSize); static final Size ZERO_SIZE; }### Answer:
@Test public void subtraction() { Size size1 = new Size(20, 10); Size size2 = new Size(10, 5); Size result = size1.minus(size2); assertEquals("Subtraction result is incorrect", new Size(10, 5), result); }