Multiplication implements Operation { @Override public boolean handles(char op) { return '*' == op; }  @Override int apply(int lhs, int rhs); @Override boolean handles(char op);  }
@Test public void shouldMatchPlusSign() { assertThat(addition.handles('*')).isTrue(); assertThat(addition.handles('/')).isFalse(); }
@Test public void shouldMatchOperation() { assertThat(addition.handles('*')).isTrue(); assertThat(addition.handles('/')).isFalse(); }