How to compare two UIDynamicProviderColor?

One solution to your unit test is by changing your code to this:

XCTAssertEqual(Style.color.cgColor, yourExpectedColor.cgColor)

In the iOS 13 at runtime it is comparing two UIDynamicProviderColor objects that return an UIColor object after running a block "(UITraitCollection) -> UIColor". So, that's the reason you have two different objects. Getting the cgColor from both you can compare them correctly. I hope I was helpfull.