Add failing test

Sources/drone-tutorial-swift/drone_tutorial_swift.swift

@@ -1,3 +1,3 @@
 struct drone_tutorial_swift {
-    var text := "Hello, World!"
+    var text = "Hello, World!"
 }

Tests/drone-tutorial-swiftTests/drone_tutorial_swiftTests.swift

@@ -9,7 +9,13 @@ final class drone_tutorial_swiftTests: XCTestCase {
         XCTAssertEqual(drone_tutorial_swift().text, "Hello, World!")
     }
 
+    func testFailure() {
+        // This is an example of a dysfunctional test case.
+        XCTAssertEqual(drone_tutorial_swift().text, "Goodbye, Cruel World!")
+    }
+
     static var allTests = [
         ("testExample", testExample),
+        ("testFailure", testFailure),
     ]
 }