public void IsValidTests() { var attribute = new YearAttribute(); Assert.IsTrue(attribute.IsValid(null)); Assert.IsTrue(attribute.IsValid("2011")); Assert.IsTrue(attribute.IsValid("9999")); Assert.IsTrue(attribute.IsValid(1234)); Assert.IsTrue(attribute.IsValid(1111)); Assert.IsTrue(attribute.IsValid(0123)); Assert.IsTrue(attribute.IsValid("0123")); Assert.IsFalse(attribute.IsValid("one")); Assert.IsFalse(attribute.IsValid("")); Assert.IsFalse(attribute.IsValid(" ")); Assert.IsFalse(attribute.IsValid("-100")); Assert.IsFalse(attribute.IsValid("20000")); Assert.IsFalse(attribute.IsValid(0)); }