CSHARP-5213: Test serverMonitoringMode=poll waits after a successful heartbeat (#1439)

Author: sanych-sun

specifications/server-discovery-and-monitoring/tests/unified/serverMonitoringMode.json

@@ -444,6 +444,69 @@
           ]
         }
       ]
+    },
+    {
+      "description": "poll waits after successful heartbeat",
+      "operations": [
+        {
+          "name": "createEntities",
+          "object": "testRunner",
+          "arguments": {
+            "entities": [
+              {
+                "client": {
+                  "id": "client",
+                  "uriOptions": {
+                    "serverMonitoringMode": "poll",
+                    "heartbeatFrequencyMS": 1000000
+                  },
+                  "useMultipleMongoses": false,
+                  "observeEvents": [
+                    "serverHeartbeatStartedEvent",
+                    "serverHeartbeatSucceededEvent"
+                  ]
+                }
+              },
+              {
+                "database": {
+                  "id": "db",
+                  "client": "client",
+                  "databaseName": "sdam-tests"
+                }
+              }
+            ]
+          }
+        },
+        {
+          "name": "waitForEvent",
+          "object": "testRunner",
+          "arguments": {
+            "client": "client",
+            "event": {
+              "serverHeartbeatSucceededEvent": {}
+            },
+            "count": 1
+          }
+        },
+        {
+          "name": "wait",
+          "object": "testRunner",
+          "arguments": {
+            "ms": 500
+          }
+        },
+        {
+          "name": "assertEventCount",
+          "object": "testRunner",
+          "arguments": {
+            "client": "client",
+            "event": {
+              "serverHeartbeatStartedEvent": {}
+            },
+            "count": 1
+          }
+        }
+      ]
     }
   ]
 }

specifications/server-discovery-and-monitoring/tests/unified/serverMonitoringMode.yml

@@ -171,3 +171,43 @@ tests:
       # Wait for the second serverHeartbeatStartedEvent to ensure we do not stream.
       - *waitForSecondHeartbeatStarted
     expectEvents: *pollingStartedEvents
+
+  - description: "poll waits after successful heartbeat"
+    operations:
+      - name: createEntities
+        object: testRunner
+        arguments:
+          entities:
+            - client:
+                id: client
+                uriOptions:
+                  serverMonitoringMode: "poll"
+                  heartbeatFrequencyMS: 1000000
+                useMultipleMongoses: false
+                observeEvents:
+                  - serverHeartbeatStartedEvent
+                  - serverHeartbeatSucceededEvent
+            - database:
+                id: db
+                client: client
+                databaseName: sdam-tests
+      # Wait for the first serverHeartbeatSucceededEvent to ensure we start polling.
+      - name: waitForEvent
+        object: testRunner
+        arguments:
+          client: client
+          event:
+            serverHeartbeatSucceededEvent: {}
+          count: 1
+      # Wait for a bit longer to ensure we wait heartbeatFrequencyMS before starting the next check.
+      - name: wait
+        object: testRunner
+        arguments:
+          ms: 500
+      - name: assertEventCount
+        object: testRunner
+        arguments:
+          client: client
+          event:
+            serverHeartbeatStartedEvent: {}
+          count: 1