CSHARP-3947: Update serverless testing for load balancer fronting single proxy. (#791)

CSHARP-3947: Update serverless testing for load balancer fronting single proxy.

Author: DmitryLukyanov

evergreen/evergreen.yml

@@ -639,8 +639,7 @@ functions:
           FRAMEWORK=${FRAMEWORK} \
           SERVERLESS_ATLAS_USER="${SERVERLESS_ATLAS_USER}" \
           SERVERLESS_ATLAS_PASSWORD="${SERVERLESS_ATLAS_PASSWORD}" \
-          SINGLE_ATLASPROXY_SERVERLESS_URI="${SINGLE_ATLASPROXY_SERVERLESS_URI}" \
-          MULTI_ATLASPROXY_SERVERLESS_URI="${MULTI_ATLASPROXY_SERVERLESS_URI}" \
+          SERVERLESS_URI="${SERVERLESS_URI}" \
           SSL=${SSL} \
             evergreen/run-serverless-tests.sh
 

evergreen/run-serverless-tests.sh

@@ -9,8 +9,7 @@ set -o errexit # Exit the script with error if any of the commands fail
 #   OS                                  Operating system, must be set
 #   SERVERLESS_ATLAS_USER               Authentication user, must be set
 #   SERVERLESS_ATLAS_PASSWORD           Authentiction password, must be set
-#   SINGLE_ATLASPROXY_SERVERLESS_URI    Single atlas proxy serverless uri, must be set
-#   MULTI_ATLASPROXY_SERVERLESS_URI     Multi atlas proxy serverless uri, must be set
+#   SERVERLESS_URI                      Single atlas proxy serverless uri, must be set
 #   SSL                                 TLS connection flag, must be "ssl"
 # Modified/exported environment variables:
 #   MONGODB_URI                         MONGODB_URI for single host with auth details and TLS and compressor parameters
@@ -47,8 +46,8 @@ else
   done
 fi
 
-export MONGODB_URI="mongodb://${SERVERLESS_ATLAS_USER}:${SERVERLESS_ATLAS_PASSWORD}@${SINGLE_ATLASPROXY_SERVERLESS_URI:10}"
-export MONGODB_URI_WITH_MULTIPLE_MONGOSES="mongodb+srv://${SERVERLESS_ATLAS_USER}:${SERVERLESS_ATLAS_PASSWORD}@${MULTI_ATLASPROXY_SERVERLESS_URI:14}"
+# Assume "mongodb+srv" protocol
+export MONGODB_URI="mongodb+srv://${SERVERLESS_ATLAS_USER}:${SERVERLESS_ATLAS_PASSWORD}@${SERVERLESS_URI:14}"
 export SERVERLESS="true"
 
 if [ "Windows_NT" = "$OS" ]; then

src/MongoDB.Driver.Core/Core/Servers/LoadBalancedServer.cs

@@ -105,12 +105,12 @@ protected override void InitializeSubClass()
             var oldDescription = Interlocked.CompareExchange(ref _currentDescription, value: newDescription, comparand: _currentDescription);
             var eventArgs = new ServerDescriptionChangedEventArgs(oldDescription, newDescription);
 
-            // propagate event to upper levels, this will be called only once
-            TriggerServerDescriptionChanged(this, eventArgs);
-
             // mark pool as ready, start the connection creation thread.
             // note that the pool can not be paused after it was marked as ready in LB mode.
             ConnectionPool.SetReady();
+
+            // propagate event to upper levels, this will be called only once
+            TriggerServerDescriptionChanged(this, eventArgs);
         }
 
         protected override void Invalidate(string reasonInvalidated, bool clearConnectionPool, TopologyVersion topologyVersion)

tests/MongoDB.Driver.Core.Tests/Core/Servers/LoadBalancedServerTests.cs

@@ -399,6 +399,19 @@ public void Invalidate_should_not_clear_the_connection_pool()
             _mockConnectionPool.Verify(p => p.Clear(It.IsAny<ObjectId>()), Times.Never);
         }
 
+        [Fact]
+        public void InitializeSubClass_should_initialize_ConnectionPool_before_cluster_updating()
+        {
+            bool setReadyHasBeenCalled = false;
+            _subject.DescriptionChanged += (s, args) =>
+            {
+                _mockConnectionPool.Verify(c => c.SetReady(), Times.Once());
+                setReadyHasBeenCalled = true; // can be called only if the above check passed
+            };
+            _subject.Initialize();
+            setReadyHasBeenCalled.Should().BeTrue();
+        }
+
         // private methods
         private Server SetupServer(bool exceptionOnConnectionOpen, bool exceptionOnConnectionAcquire)
         {