feat(NODE-5844): add iscryptd to ServerDescription (#4239)

Author: nbbeeken

src/sdam/server_description.ts

@@ -75,6 +75,8 @@ export class ServerDescription {
   maxWriteBatchSize: number | null;
   /** The max bson object size. */
   maxBsonObjectSize: number | null;
+  /** Indicates server is a mongocryptd instance. */
+  iscryptd: boolean;
 
   // NOTE: does this belong here? It seems we should gossip the cluster time at the CMAP level
   $clusterTime?: ClusterTime;
@@ -123,6 +125,7 @@ export class ServerDescription {
     this.primary = hello?.primary ?? null;
     this.me = hello?.me?.toLowerCase() ?? null;
     this.$clusterTime = hello?.$clusterTime ?? null;
+    this.iscryptd = Boolean(hello?.iscryptd);
   }
 
   get hostAddress(): HostAddress {
@@ -176,6 +179,7 @@ export class ServerDescription {
 
     return (
       other != null &&
+      other.iscryptd === this.iscryptd &&
       errorStrictEqual(this.error, other.error) &&
       this.type === other.type &&
       this.minWireVersion === other.minWireVersion &&

test/integration/server-discovery-and-monitoring/server_description.test.ts

@@ -0,0 +1,56 @@
+import { type ChildProcess, spawn } from 'node:child_process';
+
+import { expect } from 'chai';
+
+import { MongoClient } from '../../mongodb';
+
+describe('class ServerDescription', function () {
+  describe('when connecting to mongocryptd', { requires: { mongodb: '>=4.4' } }, function () {
+    let client: MongoClient;
+    const mongocryptdTestPort = '27022';
+    let childProcess: ChildProcess;
+
+    beforeEach(async function () {
+      childProcess = spawn('mongocryptd', ['--port', mongocryptdTestPort, '--ipv6'], {
+        stdio: 'ignore',
+        detached: true
+      });
+
+      childProcess.on('error', error => console.warn(this.currentTest?.fullTitle(), error));
+      client = new MongoClient(`mongodb://localhost:${mongocryptdTestPort}`);
+    });
+
+    afterEach(async function () {
+      await client?.close();
+      childProcess.kill('SIGKILL');
+    });
+
+    it('iscryptd is set to true ', async function () {
+      const descriptions = [];
+      client.on('serverDescriptionChanged', description => descriptions.push(description));
+      const hello = await client.db().command({ hello: true });
+      expect(hello).to.have.property('iscryptd', true);
+      expect(descriptions.at(-1)).to.have.nested.property('newDescription.iscryptd', true);
+    });
+  });
+
+  describe('when connecting to anything other than mongocryptd', function () {
+    let client: MongoClient;
+
+    beforeEach(async function () {
+      client = this.configuration.newClient();
+    });
+
+    afterEach(async function () {
+      await client?.close();
+    });
+
+    it('iscryptd is set to false ', async function () {
+      const descriptions = [];
+      client.on('serverDescriptionChanged', description => descriptions.push(description));
+      const hello = await client.db().command({ hello: true });
+      expect(hello).to.not.have.property('iscryptd');
+      expect(descriptions.at(-1)).to.have.nested.property('newDescription.iscryptd', false);
+    });
+  });
+});