Demonstrate UIKit bug outlined in #105

Tests/AssertHelpers.swift

@@ -78,6 +78,12 @@ func BONAssert(attributes dictionary: StyleAttributes?, query: (NSParagraphStyle
         let data2 = dataFromImage(image: image2)
         XCTAssertEqual(data1, data2, file: file, line: line)
     }
+
+    func BONAssertNotEqualImages(_ image1: BONImage, _ image2: BONImage, file: StaticString = #file, line: UInt = #line) {
+        let data1 = dataFromImage(image: image1)
+        let data2 = dataFromImage(image: image2)
+        XCTAssertNotEqual(data1, data2, file: file, line: line)
+    }
 #else
     func BONAssert<T: RawRepresentable where T.RawValue: Equatable>(attributes dictionary: StyleAttributes?, query: (NSParagraphStyle) -> T, value: T, file: StaticString = #file, line: UInt = #line) {
         guard let paragraphStyle = dictionary?[NSParagraphStyleAttributeName] as? NSParagraphStyle else {
@@ -93,4 +99,10 @@ func BONAssert(attributes dictionary: StyleAttributes?, query: (NSParagraphStyle
         let data2 = dataFromImage(image: image2)
         XCTAssertEqual(data1, data2, file: file, line: line)
     }
+
+    func BONAssertNotEqualImages(image1: BONImage, _ image2: BONImage, file: StaticString = #file, line: UInt = #line) {
+        let data1 = dataFromImage(image: image1)
+        let data2 = dataFromImage(image: image2)
+        XCTAssertNotEqual(data1, data2, file: file, line: line)
+    }
 #endif

Tests/ImageTintingTests.swift

@@ -59,4 +59,49 @@ class ImageTintingTests: XCTestCase {
         #endif
     }
 
+    #if os(OSX)
+    #else
+    func testDemonstrateUIKitTintingBug() {
+        let attachment = NSTextAttachment()
+
+        // image must be set to Template rendering mode
+        attachment.image = UIImage(named: "discount", in: testBundle, compatibleWith: nil)!.withRenderingMode(.alwaysTemplate)
+
+        let withNBSP = NSMutableAttributedString(string: BonMot.Special.noBreakSpace.description)
+        let withoutNBSP = NSMutableAttributedString(string: "")
+
+        let attachmentString = NSAttributedString(attachment: attachment)
+
+        withNBSP.append(attachmentString)
+        withoutNBSP.append(attachmentString)
+
+        withNBSP.addAttribute(NSForegroundColorAttributeName, value: UIColor.orange, range: NSRange(location: 0, length: withNBSP.length))
+        withoutNBSP.addAttribute(NSForegroundColorAttributeName, value: UIColor.orange, range: NSRange(location: 0, length: withoutNBSP.length))
+
+        let images = [withNBSP, withoutNBSP].map { attrString -> BONImage in
+            let label = UILabel()
+            label.attributedText = attrString
+            label.sizeToFit()
+            label.backgroundColor = .white
+            return ImageTintingTests.image(of: label)
+        }
+
+        // Demonstrate that UIKit will tint the image, but only if there is
+        // at least one character in the string before the attachment.
+        // See details at https://github.com/Raizlabs/BonMot/issues/105
+        BONAssertNotEqualImages(images[0], images[1])
+
+        // Uncomment these lines and enter your username to see the images for yourself:
+//        let username = "your-username-goes-here"
+//
+//        do {
+//            try UIImagePNGRepresentation(images[0])!.write(to: URL(fileURLWithPath: "/Users/\(username)/Desktop/withNBSP.png"))
+//            try UIImagePNGRepresentation(images[1])!.write(to: URL(fileURLWithPath: "/Users/\(username)/Desktop/withoutNBSP.png"))
+//        }
+//        catch {
+//            XCTFail("failed to write images. Did you remember to put the name of your home folder in the path? \(error)")
+//        }
+    }
+    #endif
+
 }