Tests: add some basic tests for Responder

Validate the default properties in a `Responder`.

Author: compnerd

Tests/UICoreTests/ResponderTests.swift

@@ -0,0 +1,19 @@
+// Copyright © 2021 Saleem Abdulrasool <[email protected]>
+// SPDX-License-Identifier: BSD-3-Clause
+
+import XCTest
+@testable import SwiftWin32
+
+final class ResponderTests: XCTestCase {
+  func testDefaultProperties() {
+    let responder: Responder = Responder()
+    XCTAssertNil(responder.next)
+    XCTAssertFalse(responder.isFirstResponder)
+    XCTAssertFalse(responder.canBecomeFirstResponder)
+    XCTAssertTrue(responder.canResignFirstResponder)
+  }
+
+  static var allTests = [
+    ("testDefaultProperties", testDefaultProperties),
+  ]
+}