Merge pull request #53 from nguillot/multiline-fixes

Add Unicode-aware line wrapping with conservative number protection

Sources/SwiftMath/MathRender/MTMathUILabel.swift

@@ -216,6 +216,7 @@ public class MTMathUILabel : MTView {
         self.layer?.isGeometryFlipped = true
 #else
         self.layer.isGeometryFlipped = true
+        self.clipsToBounds = true
 #endif
         _fontSize = 20
         _contentInsets = MTEdgeInsetsZero
@@ -305,8 +306,16 @@ public class MTMathUILabel : MTView {
             return CGSize(width: -1, height: -1)
         }
 
-        let resultWidth = displayList!.width + contentInsets.left + contentInsets.right
+        var resultWidth = displayList!.width + contentInsets.left + contentInsets.right
         let resultHeight = displayList!.ascent + displayList!.descent + contentInsets.top + contentInsets.bottom
+
+        // Ensure we don't exceed the width constraints
+        if _preferredMaxLayoutWidth > 0 && resultWidth > _preferredMaxLayoutWidth {
+            resultWidth = _preferredMaxLayoutWidth
+        } else if _preferredMaxLayoutWidth == 0 && size.width > 0 && resultWidth > size.width {
+            resultWidth = size.width
+        }
+
         return CGSize(width: resultWidth, height: resultHeight)
     }
 

Sources/SwiftMath/MathRender/MTTypesetter.swift

@@ -812,37 +812,67 @@ class MTTypesetter {
                             // Line is too wide - need to find a break point
                             let currentText = currentLine.string
 
-                            // Look for the last space before the current position
+                            // Use Unicode-aware line breaking with number protection
-                            if let lastSpaceIndex = currentText.lastIndex(of: " ") {
+                            if let breakIndex = findBestBreakPoint(in: currentText, font: styleFont.ctFont, maxWidth: maxWidth) {
-                                // Split the line at the last space
+                                // Split the line at the suggested break point
-                                let spaceOffset = currentText.distance(from: currentText.startIndex, to: lastSpaceIndex)
+                                let breakOffset = currentText.distance(from: currentText.startIndex, to: breakIndex)
 
-                                // Create attributed string for the first line (before space)
+                                // Create attributed string for the first line
-                                let firstLine = NSMutableAttributedString(string: String(currentText.prefix(spaceOffset)))
+                                let firstLine = NSMutableAttributedString(string: String(currentText.prefix(breakOffset)))
                                 firstLine.addAttribute(kCTFontAttributeName as NSAttributedString.Key, value:styleFont.ctFont as Any, range:NSMakeRange(0, firstLine.length))
 
-                                // Keep track of atoms that belong to the first line
+                                // Check if first line still exceeds maxWidth - need to find earlier break point
-                                // For simplicity, we'll split atoms at the boundary (this is approximate)
+                                let firstLineCT = CTLineCreateWithAttributedString(firstLine)
-                                let firstLineAtoms = currentAtoms
+                                let firstLineWidth = CGFloat(CTLineGetTypographicBounds(firstLineCT, nil, nil, nil))
 
-                                // Flush the first line
+                                if firstLineWidth > maxWidth {
-                                currentLine = firstLine
+                                    // Need to break earlier - find previous break point
-                                currentAtoms = firstLineAtoms
+                                    let firstLineText = firstLine.string
-                                self.addDisplayLine()
+                                    if let earlierBreakIndex = findBestBreakPoint(in: firstLineText, font: styleFont.ctFont, maxWidth: maxWidth) {
+                                        let earlierOffset = firstLineText.distance(from: firstLineText.startIndex, to: earlierBreakIndex)
+                                        let earlierLine = NSMutableAttributedString(string: String(firstLineText.prefix(earlierOffset)))
+                                        earlierLine.addAttribute(kCTFontAttributeName as NSAttributedString.Key, value:styleFont.ctFont as Any, range:NSMakeRange(0, earlierLine.length))
 
-                                // Move down for new line and reset x position
+                                        // Flush the earlier line
-                                currentPosition.y -= styleFont.fontSize * 1.5
+                                        currentLine = earlierLine
-                                currentPosition.x = 0
+                                        currentAtoms = []  // Approximate - we're splitting
+                                        self.addDisplayLine()
 
-                                // Start the new line with the content after the space
+                                        // Move down for new line
-                                let remainingText = String(currentText.suffix(from: currentText.index(after: lastSpaceIndex)))
+                                        currentPosition.y -= styleFont.fontSize * 1.5
-                                currentLine = NSMutableAttributedString(string: remainingText)
+                                        currentPosition.x = 0
 
-                                // Reset atom list for new line
+                                        // Remaining text includes everything after the earlier break
-                                currentAtoms = []
+                                        let remainingText = String(firstLineText.suffix(from: earlierBreakIndex)) +
-                                currentLineIndexRange = NSMakeRange(NSNotFound, NSNotFound)
+                                                          String(currentText.suffix(from: breakIndex))
+                                        currentLine = NSMutableAttributedString(string: remainingText)
+                                        currentAtoms = []
+                                        currentLineIndexRange = NSMakeRange(NSNotFound, NSNotFound)
+                                    }
+                                } else {
+                                    // First line fits - proceed with normal wrapping
+                                    // Keep track of atoms that belong to the first line
+                                    let firstLineAtoms = currentAtoms
+
+                                    // Flush the first line
+                                    currentLine = firstLine
+                                    currentAtoms = firstLineAtoms
+                                    self.addDisplayLine()
+
+                                    // Move down for new line and reset x position
+                                    currentPosition.y -= styleFont.fontSize * 1.5
+                                    currentPosition.x = 0
+
+                                    // Start the new line with the content after the break
+                                    let remainingText = String(currentText.suffix(from: breakIndex))
+                                    currentLine = NSMutableAttributedString(string: remainingText)
+
+                                    // Reset atom list for new line
+                                    currentAtoms = []
+                                    currentLineIndexRange = NSMakeRange(NSNotFound, NSNotFound)
+                                }
                             }
-                            // If no space found, let it overflow (better than breaking mid-word)
+                            // If no break point found, let it overflow (better than breaking mid-word)
                         }
                     }
                     // add the atom to the current range
@@ -890,7 +920,109 @@ class MTTypesetter {
             display?.width += interElementSpace
         }
     }
-    
+
+    // MARK: - Unicode-aware Line Breaking
+
+    /// Find the best break point using Core Text, with conservative number protection
+    func findBestBreakPoint(in text: String, font: CTFont, maxWidth: CGFloat) -> String.Index? {
+        let attributes: [NSAttributedString.Key: Any] = [kCTFontAttributeName as NSAttributedString.Key: font]
+        let attrString = NSAttributedString(string: text, attributes: attributes)
+        let typesetter = CTTypesetterCreateWithAttributedString(attrString as CFAttributedString)
+        let suggestedBreak = CTTypesetterSuggestLineBreak(typesetter, 0, Double(maxWidth))
+
+        guard suggestedBreak > 0 && suggestedBreak < text.count else {
+            return nil
+        }
+
+        let breakIndex = text.index(text.startIndex, offsetBy: suggestedBreak)
+
+        // Conservative check: verify we're not breaking within a number
+        if isBreakingSafeForNumbers(text: text, breakIndex: breakIndex) {
+            return breakIndex
+        }
+
+        // If the suggested break would split a number, find the previous safe break point
+        return findPreviousSafeBreak(in: text, before: breakIndex)
+    }
+
+    /// Check if breaking at this index would split a number
+    func isBreakingSafeForNumbers(text: String, breakIndex: String.Index) -> Bool {
+        guard breakIndex > text.startIndex && breakIndex < text.endIndex else {
+            return true
+        }
+
+        // Check a small window around the break point
+        let beforeIndex = text.index(before: breakIndex)
+        let charBefore = text[beforeIndex]
+        let charAfter = text[breakIndex]
+
+        // Number separators in various locales
+        let numberSeparators: Set<Character> = [
+            ".", ",",           // Decimal/thousands (EN/FR)
+            "'",                // Thousands (CH)
+            "\u{00A0}",        // Non-breaking space (FR thousands)
+            "\u{2009}",        // Thin space (sometimes used)
+            "\u{202F}"         // Narrow no-break space (FR)
+        ]
+
+        // Pattern 1: digit + separator + digit (e.g., "3.14" or "3,14")
+        if charBefore.isNumber && numberSeparators.contains(charAfter) {
+            // Check if there's a digit after the separator
+            let nextIndex = text.index(after: breakIndex)
+            if nextIndex < text.endIndex && text[nextIndex].isNumber {
+                return false  // Don't break: this looks like "3.|14"
+            }
+        }
+
+        // Pattern 2: separator + digit, check if previous is digit
+        if numberSeparators.contains(charBefore) && charAfter.isNumber {
+            // Check if there's a digit before the separator
+            if beforeIndex > text.startIndex {
+                let prevIndex = text.index(before: beforeIndex)
+                if text[prevIndex].isNumber {
+                    return false  // Don't break: this looks like "3,|14"
+                }
+            }
+        }
+
+        // Pattern 3: digit + digit (shouldn't happen with CTTypesetter, but be safe)
+        if charBefore.isNumber && charAfter.isNumber {
+            return false  // Don't break within consecutive digits
+        }
+
+        // Pattern 4: digit + space + digit (French: "1 000 000")
+        if charBefore.isNumber && charAfter.isWhitespace {
+            let nextIndex = text.index(after: breakIndex)
+            if nextIndex < text.endIndex && text[nextIndex].isNumber {
+                return false  // Don't break: this looks like "1 |000"
+            }
+        }
+
+        return true  // Safe to break
+    }
+
+    /// Find previous safe break point before the given index
+    func findPreviousSafeBreak(in text: String, before breakIndex: String.Index) -> String.Index? {
+        var currentIndex = breakIndex
+
+        // Walk backwards to find a space or safe break
+        while currentIndex > text.startIndex {
+            currentIndex = text.index(before: currentIndex)
+
+            // Prefer breaking at whitespace (safest option)
+            if text[currentIndex].isWhitespace {
+                return text.index(after: currentIndex)  // Break after the space
+            }
+
+            // Check if this would be safe
+            if isBreakingSafeForNumbers(text: text, breakIndex: currentIndex) {
+                return currentIndex
+            }
+        }
+
+        return nil
+    }
+
     /// Check if the current line exceeds maxWidth and break if needed
     func checkAndBreakLine() {
         guard maxWidth > 0 && currentLine.length > 0 else { return }
@@ -906,15 +1038,46 @@ class MTTypesetter {
         // Line is too wide - need to find a break point
         let currentText = currentLine.string
 
-        // Look for the last space before the current position
+        // Use Unicode-aware line breaking with number protection
-        if let lastSpaceIndex = currentText.lastIndex(of: " ") {
+        if let breakIndex = findBestBreakPoint(in: currentText, font: styleFont.ctFont, maxWidth: maxWidth) {
-            // Split the line at the last space
+            // Split the line at the suggested break point
-            let spaceOffset = currentText.distance(from: currentText.startIndex, to: lastSpaceIndex)
+            let breakOffset = currentText.distance(from: currentText.startIndex, to: breakIndex)
 
-            // Create attributed string for the first line (before space)
+            // Create attributed string for the first line
-            let firstLine = NSMutableAttributedString(string: String(currentText.prefix(spaceOffset)))
+            let firstLine = NSMutableAttributedString(string: String(currentText.prefix(breakOffset)))
             firstLine.addAttribute(kCTFontAttributeName as NSAttributedString.Key, value:styleFont.ctFont as Any, range:NSMakeRange(0, firstLine.length))
 
+            // Check if first line still exceeds maxWidth - need to find earlier break point
+            let firstLineCT = CTLineCreateWithAttributedString(firstLine)
+            let firstLineWidth = CGFloat(CTLineGetTypographicBounds(firstLineCT, nil, nil, nil))
+
+            if firstLineWidth > maxWidth {
+                // Need to break earlier - find previous break point
+                let firstLineText = firstLine.string
+                if let earlierBreakIndex = findBestBreakPoint(in: firstLineText, font: styleFont.ctFont, maxWidth: maxWidth) {
+                    let earlierOffset = firstLineText.distance(from: firstLineText.startIndex, to: earlierBreakIndex)
+                    let earlierLine = NSMutableAttributedString(string: String(firstLineText.prefix(earlierOffset)))
+                    earlierLine.addAttribute(kCTFontAttributeName as NSAttributedString.Key, value:styleFont.ctFont as Any, range:NSMakeRange(0, earlierLine.length))
+
+                    // Flush the earlier line
+                    currentLine = earlierLine
+                    currentAtoms = []
+                    self.addDisplayLine()
+
+                    // Move down for new line
+                    currentPosition.y -= styleFont.fontSize * 1.5
+                    currentPosition.x = 0
+
+                    // Remaining text includes everything after the earlier break
+                    let remainingText = String(firstLineText.suffix(from: earlierBreakIndex)) +
+                                      String(currentText.suffix(from: breakIndex))
+                    currentLine = NSMutableAttributedString(string: remainingText)
+                    currentAtoms = []
+                    currentLineIndexRange = NSMakeRange(NSNotFound, NSNotFound)
+                    return
+                }
+            }
+
             // Keep track of atoms that belong to the first line
             let firstLineAtoms = currentAtoms
 
@@ -927,8 +1090,8 @@ class MTTypesetter {
             currentPosition.y -= styleFont.fontSize * 1.5
             currentPosition.x = 0
 
-            // Start the new line with the content after the space
+            // Start the new line with the content after the break
-            let remainingText = String(currentText.suffix(from: currentText.index(after: lastSpaceIndex)))
+            let remainingText = String(currentText.suffix(from: breakIndex))
             currentLine = NSMutableAttributedString(string: remainingText)
 
             // Reset atom list for new line

Tests/SwiftMathTests/MTMathUILabelLineWrappingTests.swift

@@ -191,4 +191,288 @@ class MTMathUILabelLineWrappingTests: XCTestCase {
         XCTAssertNotNil(label.displayList, "Display list should be created")
         XCTAssertNil(label.error, "Should have no rendering error")
     }
+
+    func testNumberProtection_FrenchDecimal() {
+        let label = MTMathUILabel()
+        // French decimal number should NOT be broken
+        label.latex = "\\(\\text{La valeur de pi est approximativement 3,14 dans ce calcul simple.}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        // Constrain to force wrapping, but 3,14 should stay together
+        label.preferredMaxLayoutWidth = 200
+        let size = label.intrinsicContentSize
+
+        // Verify it renders without error
+        label.frame = CGRect(origin: .zero, size: size)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testNumberProtection_ThousandsSeparator() {
+        let label = MTMathUILabel()
+        // Number with comma separator should stay together
+        label.latex = "\\(\\text{The population is approximately 1,000,000 people in this city.}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        label.preferredMaxLayoutWidth = 200
+        let size = label.intrinsicContentSize
+
+        label.frame = CGRect(origin: .zero, size: size)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testNumberProtection_MixedWithText() {
+        let label = MTMathUILabel()
+        // Mixed numbers and text - numbers should be protected
+        label.latex = "\\(\\text{Results: 3.14, 2.71, and 1.41 are important constants.}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        label.preferredMaxLayoutWidth = 180
+        let size = label.intrinsicContentSize
+
+        label.frame = CGRect(origin: .zero, size: size)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    // MARK: - International Text Tests
+
+    func testChineseTextWrapping() {
+        let label = MTMathUILabel()
+        // Chinese text: "Mathematical equations are an important tool for describing natural phenomena"
+        label.latex = "\\(\\text{数学方程式は自然現象を記述するための重要なツールです。}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        // Get unconstrained size
+        let unconstrainedSize = label.intrinsicContentSize
+
+        // Set constraint to force wrapping
+        label.preferredMaxLayoutWidth = 200
+        let constrainedSize = label.intrinsicContentSize
+
+        // Chinese should wrap (can break between characters)
+        XCTAssertGreaterThan(constrainedSize.width, 0, "Width should be > 0")
+        XCTAssertLessThanOrEqual(constrainedSize.width, 200, "Width should not exceed constraint")
+        XCTAssertGreaterThan(constrainedSize.height, unconstrainedSize.height, "Height should increase when wrapped")
+
+        label.frame = CGRect(origin: .zero, size: constrainedSize)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testJapaneseTextWrapping() {
+        let label = MTMathUILabel()
+        // Japanese text (Hiragana + Kanji): "This is a mathematics explanation"
+        label.latex = "\\(\\text{これは数学の説明です。計算式を使います。}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        let unconstrainedSize = label.intrinsicContentSize
+
+        label.preferredMaxLayoutWidth = 180
+        let constrainedSize = label.intrinsicContentSize
+
+        XCTAssertGreaterThan(constrainedSize.width, 0, "Width should be > 0")
+        XCTAssertLessThanOrEqual(constrainedSize.width, 180, "Width should not exceed constraint")
+        XCTAssertGreaterThan(constrainedSize.height, unconstrainedSize.height, "Height should increase when wrapped")
+
+        label.frame = CGRect(origin: .zero, size: constrainedSize)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testKoreanTextWrapping() {
+        let label = MTMathUILabel()
+        // Korean text: "Mathematics is a very important subject"
+        label.latex = "\\(\\text{수학은 매우 중요한 과목입니다. 방정식을 배웁니다.}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        let unconstrainedSize = label.intrinsicContentSize
+
+        label.preferredMaxLayoutWidth = 200
+        let constrainedSize = label.intrinsicContentSize
+
+        // Korean uses spaces, should wrap at word boundaries
+        XCTAssertGreaterThan(constrainedSize.width, 0, "Width should be > 0")
+        XCTAssertLessThanOrEqual(constrainedSize.width, 200, "Width should not exceed constraint")
+
+        label.frame = CGRect(origin: .zero, size: constrainedSize)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testMixedLatinCJKWrapping() {
+        let label = MTMathUILabel()
+        // Mixed English and Chinese
+        label.latex = "\\(\\text{The equation is 方程式: } x^2 + y^2 = r^2 \\text{ です。}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        let unconstrainedSize = label.intrinsicContentSize
+
+        label.preferredMaxLayoutWidth = 250
+        let constrainedSize = label.intrinsicContentSize
+
+        XCTAssertGreaterThan(constrainedSize.width, 0, "Width should be > 0")
+        XCTAssertLessThanOrEqual(constrainedSize.width, 250, "Width should not exceed constraint")
+
+        label.frame = CGRect(origin: .zero, size: constrainedSize)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testEmojiGraphemeClusters() {
+        let label = MTMathUILabel()
+        // Emoji and complex grapheme clusters should not be broken
+        label.latex = "\\(\\text{Math is fun! 🎉📐📊 The formula is } E = mc^2 \\text{ 🚀✨}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        label.preferredMaxLayoutWidth = 200
+        let size = label.intrinsicContentSize
+
+        // Should wrap but not break emoji
+        XCTAssertGreaterThan(size.width, 0, "Width should be > 0")
+        XCTAssertLessThanOrEqual(size.width, 200, "Width should not exceed constraint")
+
+        label.frame = CGRect(origin: .zero, size: size)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testLongEnglishMultiSentence() {
+        let label = MTMathUILabel()
+        // Standard English multi-sentence paragraph
+        label.latex = "\\(\\text{Mathematics is the study of numbers, shapes, and patterns. It is used in science, engineering, and everyday life. Equations help us solve problems.}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        let unconstrainedSize = label.intrinsicContentSize
+
+        label.preferredMaxLayoutWidth = 300
+        let constrainedSize = label.intrinsicContentSize
+
+        // Should wrap at word boundaries (spaces)
+        XCTAssertGreaterThan(constrainedSize.width, 0, "Width should be > 0")
+        XCTAssertLessThanOrEqual(constrainedSize.width, 300, "Width should not exceed constraint")
+        XCTAssertGreaterThan(constrainedSize.height, unconstrainedSize.height, "Height should increase when wrapped")
+
+        label.frame = CGRect(origin: .zero, size: constrainedSize)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testSpanishAccentedText() {
+        let label = MTMathUILabel()
+        // Spanish with various accents
+        label.latex = "\\(\\text{La ecuación es muy útil para cálculos científicos y matemáticos.}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        let unconstrainedSize = label.intrinsicContentSize
+
+        label.preferredMaxLayoutWidth = 220
+        let constrainedSize = label.intrinsicContentSize
+
+        XCTAssertGreaterThan(constrainedSize.width, 0, "Width should be > 0")
+        XCTAssertLessThanOrEqual(constrainedSize.width, 220, "Width should not exceed constraint")
+        XCTAssertGreaterThan(constrainedSize.height, unconstrainedSize.height, "Height should increase when wrapped")
+
+        label.frame = CGRect(origin: .zero, size: constrainedSize)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
+
+    func testGermanUmlautsWrapping() {
+        let label = MTMathUILabel()
+        // German with umlauts
+        label.latex = "\\(\\text{Mathematische Gleichungen können für Berechnungen verwendet werden.}\\)"
+        label.font = MTFontManager.fontManager.defaultFont
+        label.labelMode = .text
+
+        let unconstrainedSize = label.intrinsicContentSize
+
+        label.preferredMaxLayoutWidth = 250
+        let constrainedSize = label.intrinsicContentSize
+
+        XCTAssertGreaterThan(constrainedSize.width, 0, "Width should be > 0")
+        XCTAssertLessThanOrEqual(constrainedSize.width, 250, "Width should not exceed constraint")
+        XCTAssertGreaterThan(constrainedSize.height, unconstrainedSize.height, "Height should increase when wrapped")
+
+        label.frame = CGRect(origin: .zero, size: constrainedSize)
+        #if os(macOS)
+        label.layout()
+        #else
+        label.layoutSubviews()
+        #endif
+
+        XCTAssertNotNil(label.displayList, "Display list should be created")
+        XCTAssertNil(label.error, "Should have no rendering error")
+    }
 }