         let expectation = expectationWithDescription("async test")
         var finished = 0
         let count = 512
-        var set1: NSMutableSet!
-        var set2: NSMutableSet!
+        var set1: Set<String>!
+        var set2: Set<String>!
 
         dispatch_async(queue) { [weak expectation] in
             set1 = self.getSet(count)

    }

    func testStringID() {
        XCTAssertEqual(11, countElements(flakeGen.nextStringID()))
    }

    func testLexicalCompare() {

            if finished == 2 {
                if let expectation = expectation {
                    expectation.fulfill()
                    XCTAssertTrue(set1.intersect(set2).isEmpty)
                }
            }
        }
