add prose test

Author: baileympearson

test/integration/server-discovery-and-monitoring/server_discovery_and_monitoring.prose.test.ts

@@ -1,7 +1,11 @@
 import { expect } from 'chai';
 import { once } from 'events';
 
-import { type MongoClient } from '../../../src';
+import {
+  type ConnectionCheckOutFailedEvent,
+  type ConnectionPoolClearedEvent,
+  type MongoClient
+} from '../../../src';
 import {
   CONNECTION_POOL_CLEARED,
   CONNECTION_POOL_READY,
@@ -187,4 +191,83 @@ describe('Server Discovery and Monitoring Prose Tests', function () {
       }
     });
   });
+
+  context('Connection Pool Backpressure', function () {
+    let client: MongoClient;
+    let utilClient: MongoClient;
+    const checkoutFailedEvents: Array<ConnectionCheckOutFailedEvent> = [];
+    const poolClearedEvents: Array<ConnectionPoolClearedEvent> = [];
+
+    const metadata: MongoDBMetadataUI = {
+      requires: {
+        mongodb: '>=7.0'
+      }
+    };
+
+    beforeEach(async function () {
+      client = this.configuration.newClient({}, { maxConnecting: 20 });
+
+      client.on('connectionCheckOutFailed', e => checkoutFailedEvents.push(e));
+      client.on('connectionPoolCleared', e => poolClearedEvents.push(e));
+
+      await client.connect();
+
+      utilClient = this.configuration.newClient();
+      await utilClient.connect();
+
+      const admin = utilClient.db('admin').admin();
+      await admin.command({
+        setParameter: 1,
+        ingressConnectionEstablishmentRateLimiterEnabled: true
+      });
+      await admin.command({
+        setParameter: 1,
+        ingressConnectionEstablishmentRatePerSec: 20
+      });
+      await admin.command({
+        setParameter: 1,
+        ingressConnectionEstablishmentBurstCapacitySecs: 1
+      });
+      await admin.command({
+        setParameter: 1,
+        ingressConnectionEstablishmentMaxQueueDepth: 1
+      });
+
+      await utilClient.db('test').collection('test').insertOne({});
+    });
+
+    afterEach(async function () {
+      const admin = utilClient.db('admin').admin();
+      await admin.command({
+        setParameter: 1,
+        ingressConnectionEstablishmentRateLimiterEnabled: false
+      });
+
+      await utilClient.close();
+      await client.close();
+    });
+
+    it('runs', metadata, async function () {
+      await Promise.allSettled(
+        Array.from({ length: 10 }).map(() =>
+          client
+            .db('test')
+            .collection('test')
+            .findOne({ $where: 'function() { sleep(2000); return true; }' })
+        )
+      );
+
+      await Promise.allSettled(
+        Array.from({ length: 100 }).map(() =>
+          client
+            .db('test')
+            .collection('test')
+            .findOne({ $where: 'function() { sleep(2000); return true; }' })
+        )
+      );
+
+      expect(poolClearedEvents).to.be.empty;
+      expect(checkoutFailedEvents.length).to.be.greaterThan(10);
+    });
+  });
 });