From f5efe18e1bd795d9b8963659e2e74138e04e08d9 Mon Sep 17 00:00:00 2001
From: Madeline MacDonald <t-madmac@microsoft.com>
Date: Tue, 29 May 2018 17:08:59 -0700
Subject: [PATCH] Updating profiler old event filtering and unit tests (#624)

---
 .../Profiler/ProfilerSession.cs               |  4 +--
 .../Profiler/ProfilerSessionMonitor.cs        |  5 ++-
 .../Profiler/ProfilerSessionTests.cs          | 34 +++++++++++--------
 3 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/src/Microsoft.SqlTools.ServiceLayer/Profiler/ProfilerSession.cs b/src/Microsoft.SqlTools.ServiceLayer/Profiler/ProfilerSession.cs
index 297563e8..9d5f59f7 100644
--- a/src/Microsoft.SqlTools.ServiceLayer/Profiler/ProfilerSession.cs
+++ b/src/Microsoft.SqlTools.ServiceLayer/Profiler/ProfilerSession.cs
@@ -129,7 +129,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Profiler
         /// Filter the event list to not include previously seen events, 
         /// and to exclude events that happened before the profiling session began.
         /// </summary>
-        public List<ProfilerEvent> FilterOldEvents(List<ProfilerEvent> events)
+        public void FilterOldEvents(List<ProfilerEvent> events)
         {
             if (lastSeenEvent != null)
             {
@@ -168,8 +168,6 @@ namespace Microsoft.SqlTools.ServiceLayer.Profiler
                 // ignore all events before the session began
                 events.Clear();
             }
-
-            return events;
         }
     }
 }
diff --git a/src/Microsoft.SqlTools.ServiceLayer/Profiler/ProfilerSessionMonitor.cs b/src/Microsoft.SqlTools.ServiceLayer/Profiler/ProfilerSessionMonitor.cs
index 310cb6d6..e638e930 100644
--- a/src/Microsoft.SqlTools.ServiceLayer/Profiler/ProfilerSessionMonitor.cs
+++ b/src/Microsoft.SqlTools.ServiceLayer/Profiler/ProfilerSessionMonitor.cs
@@ -160,9 +160,8 @@ namespace Microsoft.SqlTools.ServiceLayer.Profiler
                 session.IsPolling = false;
             }
 
-            return session.FilterProfilerEvents(
-                session.FilterOldEvents(events)
-            );
+            session.FilterOldEvents(events);
+            return session.FilterProfilerEvents(events);
         }
 
         /// <summary>
diff --git a/test/Microsoft.SqlTools.ServiceLayer.UnitTests/Profiler/ProfilerSessionTests.cs b/test/Microsoft.SqlTools.ServiceLayer.UnitTests/Profiler/ProfilerSessionTests.cs
index 2e7dcfa7..b43f77ce 100644
--- a/test/Microsoft.SqlTools.ServiceLayer.UnitTests/Profiler/ProfilerSessionTests.cs
+++ b/test/Microsoft.SqlTools.ServiceLayer.UnitTests/Profiler/ProfilerSessionTests.cs
@@ -24,28 +24,32 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.Profiler
         {
             // create a profiler session and get some test events
             var profilerSession = new ProfilerSession();
+            var allEvents = ProfilerTestObjects.TestProfilerEvents;
             var profilerEvents = ProfilerTestObjects.TestProfilerEvents;
-            
-            // filter old events shouldn't filter any new events
-            var newProfilerEvents = profilerSession.FilterOldEvents(profilerEvents);
-            Assert.Equal(profilerEvents.Count, newProfilerEvents.Count);
 
-            // filter should now filter all the events since they've been seen before
-            newProfilerEvents = profilerSession.FilterOldEvents(profilerEvents);
-            Assert.Equal(newProfilerEvents.Count, 0);
+            // filter all the results from the first poll
+            // these events happened before the profiler began
+            profilerSession.FilterOldEvents(profilerEvents);
+            Assert.Equal(profilerEvents.Count, 0);
 
             // add a new event
             var newEvent = new ProfilerEvent("new event", "1/1/2017");
-            profilerEvents.Add(newEvent);
+            allEvents.Add(newEvent);
 
-            // verify we only have the new event when reprocessing the event list
-            newProfilerEvents = profilerSession.FilterOldEvents(profilerEvents);
-            Assert.Equal(newProfilerEvents.Count, 1);
-            Assert.True(newProfilerEvents[0].Equals(newEvent));
+            // poll all events
+            profilerEvents.AddRange(allEvents);
 
-            // process whole list again and verify nothing new is available
-            newProfilerEvents = profilerSession.FilterOldEvents(profilerEvents);
-            Assert.Equal(newProfilerEvents.Count, 0);
+            // filtering should leave only the new event
+            profilerSession.FilterOldEvents(profilerEvents);
+            Assert.Equal(profilerEvents.Count, 1);
+            Assert.True(profilerEvents[0].Equals(newEvent));
+
+            //poll again with no new events
+            profilerEvents.AddRange(allEvents);
+
+            // filter should now filter all the events since they've been seen before
+            profilerSession.FilterOldEvents(profilerEvents);
+            Assert.Equal(profilerEvents.Count, 0);
         }