public void ZipCacherShouldCache()
        {
            var cacheKey = Guid.NewGuid().ToString();
            var zipFile = Path.Combine(Directory.GetCurrentDirectory(),"validation.zip");

            var fa = new ZipCacher(zipFile,cacheKey);

            Assert.IsFalse(fa.IsActual());

            var sw = new Stopwatch();

            sw.Start();
            fa.GetContents();
            sw.Stop();

            var firstRun = sw.ElapsedMilliseconds;

            Assert.IsTrue(fa.IsActual());

            sw.Restart();
            fa.GetContents();
            sw.Stop();

            var secondRun = sw.ElapsedMilliseconds;

            Assert.IsTrue(firstRun > secondRun);

            fa = new ZipCacher(zipFile,cacheKey);

            Assert.IsTrue(fa.IsActual());

            sw.Start();
            fa.GetContents();
            sw.Stop();

            var thirdRun = sw.ElapsedMilliseconds;
            Assert.IsTrue(thirdRun < firstRun);

            fa.Clear();
            Assert.IsFalse(fa.IsActual());

            sw.Restart();
            fa.GetContents();
            sw.Stop();

            var fourthRun = sw.ElapsedMilliseconds;
            Assert.IsTrue(fourthRun > secondRun);

            File.SetLastWriteTime(zipFile, DateTime.Now);
            Assert.IsFalse(fa.IsActual());
        }