Custom fonts don't render correctly [#10] (#11)

* Setup a baseline test for custom fonts not working correctly

#10

# Problem

When choosing certain fonts, like Avenir-Medium, NativeMarkKit renders them as the "base" font instead of the correct font.

# Solution

Create a test to reproduce the issue.

* Custom fonts don't render correctly [#10]

#10

# Problem

Certain fonts, like Avenir-Medium, don't correctly render. They end up using the "base" font style (e.g. "book" in this case).

It turns out calling `withSymbolTraits` with the existing traits mutates the description, in this case stripping off the font class.

# Solution

If no traits were specified, don't try to apply them.

Sources/NativeMarkKit/style/TextStyle+AppKit.swift

@@ -82,7 +82,10 @@ private extension FontTraits {
 
 private extension NSFontDescriptor {
     func withTraits(_ fontTraits: FontTraits) -> NSFontDescriptor {
-        withSymbolicTraits(symbolicTraits.union(fontTraits.symbolicTraits))
+        guard fontTraits != .unspecified else {
+            return self
+        }
+        return withSymbolicTraits(symbolicTraits.union(fontTraits.symbolicTraits))
     }
 }
 
@@ -106,19 +109,12 @@ private extension FontDescriptor {
                 return NSFont.monospacedSystemFont(ofSize: size.pointSize, weight: .regular)
                     .fontDescriptor
             } else {
-                let traits: [NSFontDescriptor.TraitKey: Any] = [
-                    .symbolic: NSFontMonoSpaceTrait
-                ]
-                return NSFontDescriptor(fontAttributes: [
-                    .traits: traits,
-                    .size: size.pointSize
-                ])
+                return NSFont.systemFont(ofSize: size.pointSize)
+                    .fontDescriptor
+                    .withSymbolicTraits(.monoSpace)
             }
         case let .custom(fontName):
-            return NSFontDescriptor(fontAttributes: [
-                .name: fontName,
-                .size: size.pointSize
-            ])
+            return NSFontDescriptor(name: fontName, size: size.pointSize)
         }
     }
 }

Sources/NativeMarkKit/style/TextStyle+UIKit.swift

@@ -93,7 +93,11 @@ private extension FontTraits {
 
 private extension UIFontDescriptor {
     func withTraits(_ fontTraits: FontTraits) -> UIFontDescriptor {
-        withSymbolicTraits(symbolicTraits.union(fontTraits.symbolicTraits)) ?? self
+        guard fontTraits != .unspecified else {
+            return self
+        }
+
+        return withSymbolicTraits(symbolicTraits.union(fontTraits.symbolicTraits)) ?? self
     }
 }
 
@@ -116,19 +120,14 @@ private extension FontDescriptor {
                 return UIFont.monospacedSystemFont(ofSize: size.pointSize, weight: .regular)
                     .fontDescriptor
             } else {
-                let traits: [UIFontDescriptor.TraitKey: Any] = [
-                    .symbolic: UIFontDescriptor.SymbolicTraits.traitMonoSpace.rawValue
-                ]
-                return UIFontDescriptor(fontAttributes: [
-                    .traits: traits,
-                    .size: size.pointSize
-                ])
+                let baseDescriptor = UIFont.systemFont(ofSize: size.pointSize)
+                    .fontDescriptor
+
+                return baseDescriptor.withSymbolicTraits(.traitMonoSpace)
+                    ?? baseDescriptor
             }
         case let .custom(fontName):
-            return UIFontDescriptor(fontAttributes: [
-                .name: fontName,
-                .size: size.pointSize
-            ])
+            return UIFontDescriptor(name: fontName, size: size.pointSize)
         }
     }
 }

Tests/NativeMarkKitTests/BasicRenderTest.swift

@@ -52,6 +52,22 @@ final class BasicRenderTest: XCTestCase {
         XCTAssert(testCase.isPassing(for: self))
     }
 
+    func testHelloWorldWithCustomFontTake2() {
+        let style = StyleSheet.default.duplicate().mutate(
+                block: [
+                    .document: [
+                        .textStyle(.custom(name: .custom("Avenir-Roman"), size: .fixed(19))),
+                        .backgroundColor(.white),
+                        .textColor(.black)
+                    ],
+                ])
+        let testCase = RenderTestCase(name: "HelloWorldWithCustomFontTakeTwo",
+                                      nativeMark: "Avenir Avenir Avenir Avenir",
+                                      styleSheet: style,
+                                      width: 320)
+        XCTAssert(testCase.isPassing(for: self))
+    }
+
     func testParagraphs() {
         let nativeMark = """
 This is the first