@Theory
public void unitLaw(Integer x) {
Integer left = sumMonoid.multiply(0, x);
Integer right = sumMonoid.multiply(x, 0);
assertThat(left, is(x));
assertThat(right, is(x));
}
@Theory
public void sumBinOp(Integer x, Integer y) {
Integer actual = sumMonoid.multiply(x, y);
assertThat(actual, is(x + y));
}
@Test
public void sumUnitIsZero() {
assertThat(sumMonoid.unit(), is(0));
}