C# Language Test flags-style enum values with bitwise logic


Example

A flags-style enum value needs to be tested with bitwise logic because it may not match any single value.

[Flags]
enum FlagsEnum
{
    Option1 = 1,
    Option2 = 2,
    Option3 = 4,
    Option2And3 = Option2 | Option3;

    Default = Option1 | Option3,
}

The Default value is actually a combination of two others merged with a bitwise OR. Therefore to test for the presence of a flag we need to use a bitwise AND.

var value = FlagsEnum.Default;

bool isOption2And3Set = (value & FlagsEnum.Option2And3) == FlagsEnum.Option2And3;

Assert.True(isOption2And3Set);