Swift Unit test- How do I assert that a CGColor is what it's supposed to be?

Question

Using Xcode V7.2. Trying to unit test, need to verify that the correct color has been set, and get this message:

Cannot invoke 'XCTAssertEqual' with an argument list of type '(CGColor, CGColor)'

How do I assert that a CGColor is what it's supposed to be?

score 6 · Accepted Answer · answered Dec 31 '15 at 15:32

6

Use XCTAssert and test whether CGColorEqualToColor is true.

answered Dec 31 '15 at 15:32

matt

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As of Swift 3.0 / Xcode 8.0 this no longer works. It results in the error "CGColorEqualToColor is unavailable: use == instead". But ==/isEqual does not always work as explained in [this SO answer](http://stackoverflow.com/a/8899384/2466193). I have reverted to breaking it down with getRed(_, green, blue, alpha) and comparing the individual components, – Ali Beadle Oct 08 '16 at 14:47
@AliBeadle That's important info. Could you give that as a separate answer? I'll happily upvote it. – matt Oct 08 '16 at 14:54
(Of course one might argue that `==` _does_ "work" and that the fact that it doesn't work with different color spaces is correct.) – matt Oct 08 '16 at 14:55
Will do. Good point about ==, will amend in the posted answer. – Ali Beadle Oct 08 '16 at 17:53

score 6 · Answer 2 · edited Jun 18 '19 at 21:56

As of Swift 3.0 / Xcode 8.0 CGColorEqualToColor also no longer works, it results in the error "CGColorEqualToColor is unavailable: use == instead".

== or isEqual has the limitation that it:

will return NO[/False] when comparing colors that are in different models/spaces (for instance #FFF with [UIColor whiteColor])

(From this SO answer) which may not be the desired behaviour.

It is cumbersome, but I break the colour down into its R/G/B/Alpha components and compare those, e.g.:

    var red1:CGFloat=0, green1:CGFloat=0, blue1:CGFloat=0, alpha1:CGFloat=0
    colour1.getRed(&red1, green:&green1, blue:&blue1, alpha:&alpha1)

    var red2:CGFloat=0, green2:CGFloat=0, blue2:CGFloat=0, alpha2:CGFloat=0
    colour2.getRed(&red2, green:&green2, blue:&blue2, alpha:&alpha2)

    XCTAssertEqual(red1, red2)
    XCTAssertEqual(green1, green2)
    XCTAssertEqual(blue1, blue2)
    XCTAssertEqual(alpha1, alpha2)

EDIT: (adding this to your answer instead of creating a new answer :)

Here's a UIColor extension for easier use:

import UIKit

extension UIColor {
    func isEqualTo(_ color: UIColor) -> Bool {
        var red1: CGFloat = 0, green1: CGFloat = 0, blue1: CGFloat = 0, alpha1: CGFloat = 0
        getRed(&red1, green:&green1, blue:&blue1, alpha:&alpha1)

        var red2: CGFloat = 0, green2: CGFloat = 0, blue2: CGFloat = 0, alpha2: CGFloat = 0
        color.getRed(&red2, green:&green2, blue:&blue2, alpha:&alpha2)

        return red1 == red2 && green1 == green2 && blue1 == blue2 && alpha1 == alpha2
    }
}

and use it like this:

XCTAssertTrue(cell.backgroundColor!.isEqualTo(.clear))

OR - you can use an Equatable function

func ==(lhs: UIColor, rhs: UIColor) -> Bool {
    var lr: CGFloat = 0, lg: CGFloat = 0, lb: CGFloat = 0, la: CGFloat = 0
    lhs.getRed(&lr, green:&lg, blue:&lb, alpha:&la)
    var rr: CGFloat = 0, rg: CGFloat = 0, rb: CGFloat = 0, ra: CGFloat = 0
    rhs.getRed(&rr, green: &rg, blue: &rb, alpha: &ra)
    return lr == rr && lg == rg && lb == rb && la == ra
}

and use it like this:

XCTAssertTrue(cell.backgroundColor == UIColor.clear)

I'd be careful using equatables on floats, which is what these really are. Depending on how you're creating your colors, you could have differences resulting from floating point rounding/truncation. — Victor Engel, Aug 21 '20 at 20:38

Swift Unit test- How do I assert that a CGColor is what it's supposed to be?

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