### Question:
Transition { @Override public String toString() { return new StringBuilder().append(type).append(Constant.SPACE).append(groups).toString(); } Transition(TransitionType type, String groupIn, String groupOut); TransitionType getType(); String getIn(); String getOut(); @Override int hashCode(); @Override boolean equals(Object object); @Override String toString();  }### Answer:
@Test void testToString() { assertEquals(TransitionType.CENTER.name() + " a -> b", new Transition(TransitionType.CENTER, "a", "b").toString()); }