  @Test
  public void testAxioms() {

    Spec.given(new XGH())
        .expect(doing(xgh -> xgh.axiom(1)), to().succeed())
        .expect(doing(xgh -> xgh.axiom(23)), to().fail())
        .expect(doing(xgh -> xgh.axiom(0)), to().fail());

    for (int i = 1 ; i <= 22 ; i++) {
      Spec.given(new XGH())
          .expect(axiom(i), to().have(number(i)));
    }
  }