How do you test an enum flag combination?

Question

Let’s say I have an enum flag:

[Flags]
public enum ColorType
{
    None = 0,
    Red = 1 << 0,
    White = 1<<1,
    Yellow = 1 << 2,
    Blue = 1 << 3,
    All = Red | White | Yellow | Blue
}

I have the below function, which parameter is a combination of flag, such as DoSomething( ColorType.Blue | ColorType.Yellow ).

public void DoSomethingr(ColorType theColorTypes)
{
        if (theColorTypes.HasFlag(All)) Foo1();
        if (theColorTypes.HasFlag(White) && theColorTypes.HasFlag(Red) )  Foo2();
        if (!theColorTypes.HasFlag(Blue)) Foo3();
        . . . 
}

Is there an easy way to test all of possible flag bitwise combination?

[Test] 
public void Test1(ColorType.Red | ColorType.Yellow | ColorType.White) 

[Test]
public void Test1(ColorType.Red | ColorType.Yellow | ColorType.white | ColorType.Blue) 

Thanks

Answer 1

Loop over all the possible values and put it in a TestCaseSource to generate a different test for each enumeration value:

public IEnumerable<ColorType> TestCaseSource 
{ 
    get
    {
        int start = (int)ColorType.None;
        int count = (int)ColorType.All - start + 1;
        return Enumerable.Range(start, count).Select(i => (ColorType)i); 
    } 
}

[TestCaseSource("TestCaseSource")]
public void Test1(ColorType colorType)
{
    // whatever your test is
}