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