feat(NODE-5844): add iscryptd to ServerDescription

src/sdam/server_description.ts

@@ -69,6 +69,8 @@ export class ServerDescription {
   setVersion: number | null;
   electionId: ObjectId | null;
   logicalSessionTimeoutMinutes: 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
   $clusterTime?: ClusterTime;
@@ -114,6 +116,7 @@ export class ServerDescription {
     this.primary = hello?.primary ?? null;
     this.me = hello?.me?.toLowerCase() ?? null;
     this.$clusterTime = hello?.$clusterTime ?? null;
+    this.iscryptd = Boolean(hello?.iscryptd);
   }
 
   get hostAddress(): HostAddress {
@@ -167,6 +170,7 @@ 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 +1,37 @@
+import { type ChildProcess, spawn } from 'node:child_process';
+
+import { expect } from 'chai';
+
+import { MongoClient } from '../../mongodb';
+
+describe('ServerDescription xxx', function () {
+  let client: MongoClient;
+  const mongocryptdTestPort = '27022';
+  let childProcess: ChildProcess;
+
+  beforeEach(async () => {
+    childProcess = spawn('mongocryptd', ['--port', mongocryptdTestPort, '--ipv6'], {
+      stdio: 'ignore',
+      detached: true
+    });
+
+    childProcess.on('error', err => {
+      console.warn('Sessions prose mongocryptd error:', err);
+    });
+    client = new MongoClient(`mongodb://localhost:${mongocryptdTestPort}`);
+  });
+
+  afterEach(async () => {
+    await client?.close();
+    childProcess.kill('SIGKILL');
+  });
+
+  it('iscryptd is set to true when connecting to mongocryptd', 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); // sanity check
+    expect(hello).to.not.have.property('logicalSessionTimeoutMinutes');
+    expect(descriptions.at(-1)).to.have.nested.property('newDescription.iscryptd', true);
+  });
+});