public void Resolve_ReturnsNotNullOnlyOnSuccess(string hostname, bool shouldEmptyResult)
        {
            testDnsResolver = new TestDnsResolver("correct");
            var sut       = new HostnameResolverWithCache(TimeSpan.FromMinutes(1), testDnsResolver);
            var ipAddress = sut.Resolve(hostname);

            Assert.AreEqual(ipAddress == null, shouldEmptyResult);
        }
 public void SetUp()
 {
     testDnsResolver = new TestDnsResolver();
 }