public void MixWithIsNotAssociative()
{
// Counter-example
var x = new RgbColor(67, 108, 13);
var y = new RgbColor(33, 114, 130);
var z = new RgbColor(38, 104, 245);
Assert.NotEqual(
x.MixWith(y).MixWith(z),
x.MixWith(y.MixWith(z)));
}
public void MixWithIsCommutative()
{
var x = new RgbColor(67, 108, 13);
var y = new RgbColor(33, 114, 130);
Assert.Equal(
x.MixWith(y),
y.MixWith(x));
}
public void MixWithIsNotInvertible()
{
// Counter-example
var a = new RgbColor(94, 35, 172);
var b = new RgbColor(151, 185, 7);
Assert.DoesNotContain(RgbColor.All, x => a.MixWith(x) == b);
Assert.DoesNotContain(RgbColor.All, y => y.MixWith(a) == b);
}
public void MixWithHasNoIdentity()
{
var nearBlack = new RgbColor(1, 1, 1);
var identityCandidates = from e in RgbColor.All
where nearBlack.MixWith(e) == nearBlack
select e;
// Verify that there's only a single candidate:
var identityCandidate = Assert.Single(identityCandidates);
// Demonstrate that the candidate does behave like identity for
// nearBlack:
Assert.Equal(nearBlack, nearBlack.MixWith(identityCandidate));
Assert.Equal(nearBlack, identityCandidate.MixWith(nearBlack));
// Counter-example
var counterExample = new RgbColor(3, 3, 3);
Assert.NotEqual(
counterExample,
counterExample.MixWith(identityCandidate));
}
