public void SetFlag_DoesNotMutateArgument()
{
NoZeroFlags fourNotSet = NoZeroFlags.Three;
Assert.That(fourNotSet.HasFlag(NoZeroFlags.Four), Is.False, "does not contain four initially");
fourNotSet.SetFlag(NoZeroFlags.Four); // no assignation
Assert.That(fourNotSet.HasFlag(NoZeroFlags.Four), Is.False, "no mutation");
}
public void SetFlag_AlreadySetValue_ValueLeftAsSet()
{
NoZeroFlags fourAlreadySet = NoZeroFlags.Three | NoZeroFlags.Four;
Assert.That(fourAlreadySet.HasFlag(NoZeroFlags.Four), Is.True, "contains four initially");
fourAlreadySet = fourAlreadySet.SetFlag(NoZeroFlags.Four);
Assert.That(fourAlreadySet.HasFlag(NoZeroFlags.Four), Is.True, "still contains four");
}