@Test
    public void testParseMassesOnOneMass() {
        List<Mass> masses = GrammarParser.parseMasses("hand 5.2 -6.4");
        assertEquals(1, masses.size());
        assertEquals(5.2, masses.get(0).getX(), DELTA);
        assertEquals(-6.4, masses.get(0).getY(), DELTA);
    }