adding tests

BlueprintUI/Tests/AccessibililtyTraitsTests.swift

@@ -0,0 +1,35 @@
+import BlueprintUI
+import UIKit
+import XCTest
+
+
+class UIAccessibilityTraits_Tests: XCTestCase {
+
+    func test_backButton() throws {
+
+        let root = UIViewController()
+        let second = UIViewController()
+        let navigationController = UINavigationController()
+        navigationController.viewControllers = [root, second]
+
+        try show(vc: navigationController) { _ in
+            let button = try XCTUnwrap(
+                navigationController.navigationBar.findSubview(ofType: UIControl.self)
+            )
+
+            /// The `.backButton` trait is private, so this test is here to verify it does not change.
+
+            XCTAssertEqual(button.accessibilityTraits, .backButton)
+        }
+    }
+
+    func test_toggleSwitch() {
+        if #available(iOS 17.0, *) {
+            /// The `.toggleButton` trait is exposed iOS 17, so this test is here to verify it matches ours.
+            XCTAssertEqual(UIAccessibilityTraits._toggleButton, UIAccessibilityTraits.toggleButton)
+        }
+        let uiSwitch = UISwitch()
+        /// The `.toggleButton` trait is private prior to iOS 17, so this test is here to verify it exists on prior versions.
+        XCTAssertTrue(uiSwitch.accessibilityTraits.contains(._toggleButton))
+    }
+}

BlueprintUI/Tests/Extensions/UIView+Testing.swift

@@ -0,0 +1,32 @@
+import UIKit
+import XCTest
+
+extension UIView {
+    /// Does a breadth-first search for a subview of the given type, optionally matching a
+    /// predicate.
+    public func findSubview<View: UIView>(
+        ofType viewType: View.Type,
+        where predicate: (View) -> Bool = { _ in true }
+    ) -> View? {
+        for subview in subviews {
+            if let match = subview as? View, predicate(match) {
+                return match
+            }
+        }
+
+        for view in subviews {
+            if let match = view.findSubview(ofType: viewType, where: predicate) {
+                return match
+            }
+        }
+
+        return nil
+    }
+
+    public func expectedChild<T: UIView>(ofType viewType: T.Type) throws -> T {
+        try XCTUnwrap(
+            findSubview(ofType: viewType),
+            "Expected to find child of type \(T.self) but no child was found"
+        )
+    }
+}