public void TestGetSafetyByContainsOnlyDigits()
{
Assert.AreEqual(0, passwordStrength.GetSafetyByContainsOnlyDigits("a"));
Assert.AreEqual(0, passwordStrength.GetSafetyByContainsOnlyDigits("a1"));
Assert.AreEqual(-1, passwordStrength.GetSafetyByContainsOnlyDigits("1"));
Assert.AreEqual(-2, passwordStrength.GetSafetyByContainsOnlyDigits("11"));
}