public void IsGreaterThan_T_IComparable_fails_when_equal(int candidate) =>
 Invoking(() =>
          Ensure.That(() => candidate)
          .IsGreaterThan(candidate, TestComparer <int> .AlwaysEqual()))
 .Should().Throw <GuardClauseNotMetException>()
 .WithMessage(nameof(candidate).ShouldBeGreaterThan(candidate));
 public void IsLessThanOrEqualTo_Expression_IComparable_succeeds_when_equal(int candidate) =>
 Invoking(() =>
          Ensure.That(() => candidate)
          .IsLessThanOrEqualTo(() => candidate, TestComparer <int> .AlwaysEqual()))
 .Should().NotThrow();