Add support for Mac Catalyst

Makefile

@@ -3,6 +3,11 @@ test-macos:
 			-scheme MarkdownUI \
 			-destination platform="macOS"
 
+test-macos-maccatalyst:
+	xcodebuild test \
+			-scheme MarkdownUI \
+			-destination platform="macOS,variant=Mac Catalyst"
+
 test-ios:
 	xcodebuild test \
 			-scheme MarkdownUI \
@@ -18,7 +23,7 @@ test-watchos:
 			-scheme MarkdownUI \
 			-destination platform="watchOS Simulator,name=Apple Watch SE (40mm) (2nd generation)"
 
-test: test-macos test-ios test-tvos test-watchos
+test: test-macos test-macos-maccatalyst test-ios test-tvos test-watchos
 
 format:
 	swift format --in-place --recursive .

Package.swift

@@ -8,6 +8,7 @@ let package = Package(
     .macOS(.v12),
     .iOS(.v15),
     .tvOS(.v15),
+    .macCatalyst(.v15),
     .watchOS(.v8),
   ],
   products: [

Tests/MarkdownUITests/MarkdownImageTests.swift

@@ -8,6 +8,10 @@
   final class MarkdownImageTests: XCTestCase {
     private let layout = SwiftUISnapshotLayout.device(config: .iPhone8)
 
+    override func setUpWithError() throws {
+      try XCTSkipIf(UIDevice.current.userInterfaceIdiom == .pad, "Skipping on Mac Catalyst")
+    }
+
     func testFailingImage() {
       let view = Markdown {
         #"""

Tests/MarkdownUITests/MarkdownListTests.swift

@@ -8,6 +8,10 @@
   final class MarkdownListTests: XCTestCase {
     private let layout = SwiftUISnapshotLayout.device(config: .iPhone8)
 
+    override func setUpWithError() throws {
+      try XCTSkipIf(UIDevice.current.userInterfaceIdiom == .pad, "Skipping on Mac Catalyst")
+    }
+
     func testTaskList() {
       let view = Markdown {
         #"""

Tests/MarkdownUITests/MarkdownTests.swift

@@ -8,6 +8,10 @@
   final class MarkdownTests: XCTestCase {
     private let layout = SwiftUISnapshotLayout.device(config: .iPhone8)
 
+    override func setUpWithError() throws {
+      try XCTSkipIf(UIDevice.current.userInterfaceIdiom == .pad, "Skipping on Mac Catalyst")
+    }
+
     func testBlockquote() {
       let view = Markdown {
         #"""

Tests/MarkdownUITests/ThemeDocCTests.swift

@@ -8,6 +8,10 @@
   final class ThemeDocCTests: XCTestCase {
     private let layout = SwiftUISnapshotLayout.device(config: .iPhone8)
 
+    override func setUpWithError() throws {
+      try XCTSkipIf(UIDevice.current.userInterfaceIdiom == .pad, "Skipping on Mac Catalyst")
+    }
+
     func testInlines() {
       let view = ThemePreview(theme: .docC) {
         #"""

Tests/MarkdownUITests/ThemeGitHubTests.swift

@@ -9,6 +9,10 @@
     private let layout = SwiftUISnapshotLayout.device(config: .iPhone8)
     private let perceptualPrecision: Float = 0.97
 
+    override func setUpWithError() throws {
+      try XCTSkipIf(UIDevice.current.userInterfaceIdiom == .pad, "Skipping on Mac Catalyst")
+    }
+
     func testInlines() {
       let view = ThemePreview(theme: .gitHub) {
         #"""