Add implementation for NSURL copy()

Author: mbvreddy

Foundation/NSURL.swift

@@ -81,7 +81,7 @@ public class NSURL : NSObject, NSSecureCoding, NSCopying {
     }
 
     public func copyWithZone(_ zone: NSZone) -> AnyObject {
-        NSUnimplemented()
+        return self
     }
 
     static public func supportsSecureCoding() -> Bool {
@@ -587,7 +587,7 @@ public class NSURLQueryItem : NSObject, NSSecureCoding, NSCopying {
     }
 
     public func copyWithZone(_ zone: NSZone) -> AnyObject {
-        NSUnimplemented()
+        return self
     }
 
     public static func supportsSecureCoding() -> Bool {

TestFoundation/TestNSURL.swift

@@ -60,7 +60,8 @@ class TestNSURL : XCTestCase {
             // TODO: these tests fail on linux, more investigation is needed
             ("test_fileURLWithPath", test_fileURLWithPath),
             ("test_fileURLWithPath_isDirectory", test_fileURLWithPath_isDirectory),
-            ("test_URLByResolvingSymlinksInPath", test_URLByResolvingSymlinksInPath)
+            ("test_URLByResolvingSymlinksInPath", test_URLByResolvingSymlinksInPath),
+            ("test_copy", test_copy)
         ]
     }
 
@@ -417,6 +418,16 @@ class TestNSURL : XCTestCase {
             XCTAssertEqual(result, "file:///tmp/")
         }
     }
+
+    func test_copy() {
+        let url = NSURL(string: "https://www.swift.org")
+        let urlCopy = url!.copy() as! NSURL
+        XCTAssertTrue(url === urlCopy)
+
+        let queryItem = NSURLQueryItem(name: "id", value: "23")
+        let queryItemCopy = queryItem.copy() as! NSURLQueryItem
+        XCTAssertTrue(queryItem === queryItemCopy)
+    }
 }
 
 class TestNSURLComponents : XCTestCase {