func testDeallocCgImageWhenPngRepresentationWasCreated() {
    weak var weakCgImage: CGImage?
    do {
        let data: [UInt8] = [0, 0, 0, 0]
        let provider: CGDataProvider = CGDataProvider(data: Data(
            bytes: UnsafeMutableRawPointer(mutating: data),
            count: 4
        ) as CFData)!

        let cgImage = CGImage(
            width: 1,
            height: 1,
            bitsPerComponent: 1 * 8,
            bitsPerPixel: 4 * 8,
            bytesPerRow: 4 * 1,
            space: CGColorSpaceCreateDeviceRGB(),
            bitmapInfo: CGBitmapInfo(),
            provider: provider,
            decode: nil,
            shouldInterpolate: false,
            intent: CGColorRenderingIntent.defaultIntent
        )!
        weakCgImage = cgImage

        let imageRep: NSBitmapImageRep = NSBitmapImageRep(cgImage: cgImage)
        imageRep.size = CGSize(width: CGFloat(1), height: CGFloat(1))

        // the following line causes the memory leak (if removed the test is green)
        _ = imageRep.representation(using: .png, properties: [:])
        XCTAssertNotNil(weakCgImage)
    }
    // test if cg image was deallocated
    XCTAssertNil(weakCgImage)
} 

_ = imageRep.representation(using: .png, properties: [:])