         XCTAssertEqual(Set(expected), Set(toNewDiffs.changes))
         XCTAssertEqual(Set(expected), Set(fromOldDiffs.changes))
     }
-}
+
+    private func _randomArray(count: Int) -> Array<Int> {
+        return (0..<count).map { _ in Int(arc4random_uniform(10)) }
+    }
+}

        ]
        let expected: Array<Difference> = [.move(1, 2), .move(2, 1)]
        _assert(expected: expected, equalsOld: old, diffedWithNew: new)
    }

    // MARK: Helpers

            ("testUpdateIndexOneWithDuplicatesAtStartAndEnd", testUpdateIndexOneWithDuplicatesAtStartAndEnd),
            ("testInsertIndexZeroAndFiveWithDuplicatesAtStartAndEnd", testInsertIndexZeroAndFiveWithDuplicatesAtStartAndEnd),
            ("testSwapIndexesOneAndTwoWithDuplicatesAtStartAndEnd", testSwapIndexesOneAndTwoWithDuplicatesAtStartAndEnd),
            ("testPerformanceWithOneThousandIntegers", testPerformanceWithOneThousandIntegers),
        ]
    }

