Merge pull request #1383 from wordpress-mobile/fix/crash-comment-attachment-renderer

Fix crash when attempting to render Gutenberg comment

Author: itsmeichigo

Aztec/Classes/Renderers/CommentAttachmentRenderer.swift

@@ -36,15 +36,20 @@ extension CommentAttachmentRenderer: TextViewAttachmentImageProvider {
     }
 
     public func textView(_ textView: TextView, imageFor attachment: NSTextAttachment, with size: CGSize) -> UIImage? {
-        UIGraphicsBeginImageContextWithOptions(size, false, 0)
-
         // Either this is a comment attachment, or the logic is broken.
         let commentAttachment = attachment as! CommentAttachment
 
         guard !isGutenbergComment(commentAttachment) else {
             return nil
         }
 
+        // Extra safety check to avoid crash when attempting to render image with size smaller than 0
+        guard size.width > 0 && size.height > 0 else {
+            return nil
+        }
+
+        UIGraphicsBeginImageContextWithOptions(size, false, 0)
+
         let message = messageAttributedString()
         let targetRect = boundingRect(for: message, size: size)
 

AztecTests/Renderers/CommentAttachmentRendererTests.swift

@@ -46,4 +46,31 @@ class CommentAttachmentRendererTests: XCTestCase {
 
         XCTAssertEqual(bounds, expectedBounds)
     }
+
+    func testImageForGutenbergCommentIsNil() {
+        // Given
+        let textView = TextViewStub()
+        let gutenbergComment = CommentAttachment()
+        gutenbergComment.text = "wp:paragraph"
+        let renderer = CommentAttachmentRenderer(font: .systemFont(ofSize: 12))
+
+        // When
+        let image = renderer.textView(textView, imageFor: gutenbergComment, with: .init(width: 2, height: 2))
+
+        // Then
+        XCTAssertNil(image)
+    }
+
+    func testRenderingImageWithIllegalSizeReturnsNil() {
+        // Given
+        let textView = TextViewStub()
+        let attachment = CommentAttachment()
+        let renderer = CommentAttachmentRenderer(font: .systemFont(ofSize: 12))
+
+        // When
+        let image = renderer.textView(textView, imageFor: attachment, with: .init(width: -1, height: -1))
+
+        // Then
+        XCTAssertNil(image)
+    }
 }

Example/Example/SampleContent/content.html

@@ -3,6 +3,7 @@ <h1>Welcome To Aztec</h1>
 <p>Aztec goal is to be an component that allows display and editition of HTML. <br/>
 It aims to supports the most common character styles, paragraph styles and multimedia elements.
 </p>
+<p><!-- wp:paragraph --></p>
 
 <!--more-->
 
@@ -25,11 +26,19 @@ <h2>Paragraph Styles</h2>
 <h3>Lists</h3>
 
 <h4>Unordered List:</h4>
+<!-- wp:list -->
 <ul>
+    <!-- wp:list-item -->
     <li>One</li>
+    <!-- /wp:list-item -->
+    <!-- wp:list-item -->
     <li>Two</li>
+    <!-- /wp:list-item -->
+    <!-- wp:list-item -->
     <li>Three</li>
+    <!-- wp:list-item -->
 </ul>
+<!-- /wp:list -->
 
 <h4>Ordered List:</h4>
 <ol>