fixed parsing issue

Author: filipw

src/WebApi.OutputCache.V2/CacheOutputAttribute.cs

@@ -205,7 +205,16 @@ public override void OnActionExecuting(HttpActionContext actionContext)
             if (val == null) return;
 
             var contenttype = _webApiCache.Get<MediaTypeHeaderValue>(cachekey + Constants.ContentTypeKey) ?? responseMediaType;
-            var contentGenerationTimestamp = DateTimeOffset.Parse(_webApiCache.Get<string>(cachekey + Constants.GenerationTimestampKey));
+            var contentGeneration = _webApiCache.Get<string>(cachekey + Constants.GenerationTimestampKey);
+
+            DateTimeOffset? contentGenerationTimestamp = null;
+            if (contentGeneration != null)
+            {
+                if (DateTimeOffset.TryParse(contentGeneration, out DateTimeOffset parsedContentGenerationTimestamp))
+                {
+                    contentGenerationTimestamp = parsedContentGenerationTimestamp;
+                }
+            };
 
             actionContext.Response = actionContext.Request.CreateResponse();
             actionContext.Response.Content = new ByteArrayContent(val);

test/WebApi.OutputCache.V2.Tests/ClientSideTests.cs

@@ -123,7 +123,7 @@ public void maxage_mustrevalidate_headers_correct_with_cacheuntil()
         {
             var client = new HttpClient(_server);
             var result = client.GetAsync(_url + "Get_until25012015_1700").Result;
-            var clientTimeSpanSeconds = new SpecificTime(2017, 01, 25, 17, 0, 0).Execute(DateTime.Now).ClientTimeSpan.TotalSeconds;
+            var clientTimeSpanSeconds = new SpecificTime(2019, 01, 25, 17, 0, 0).Execute(DateTime.Now).ClientTimeSpan.TotalSeconds;
             var resultCacheControlSeconds = ((TimeSpan) result.Headers.CacheControl.MaxAge).TotalSeconds;
             Assert.IsTrue(Math.Round(clientTimeSpanSeconds - resultCacheControlSeconds) == 0);
             Assert.IsFalse(result.Headers.CacheControl.MustRevalidate);

test/WebApi.OutputCache.V2.Tests/TestControllers/SampleController.cs

@@ -74,7 +74,7 @@ public string Get_s50_exclude_true(int id)
             return "test" + id;
         }
 
-        [CacheOutputUntil(2017,01,25,17,00)]
+        [CacheOutputUntil(2019,01,25,17,00)]
         public string Get_until25012015_1700()
         {
             return "test";