fix(NODE-6858): treat MongoServerSelectionError as a resumable error for Change Streams

src/error.ts

@@ -1551,6 +1551,10 @@ export function isResumableError(error?: Error, wireVersion?: number): boolean {
     return true;
   }
 
+  if (error instanceof MongoServerSelectionError) {
+    return true;
+  }
+
   if (wireVersion != null && wireVersion >= 9) {
     // DRIVERS-1308: For 4.4 drivers running against 4.4 servers, drivers will add a special case to treat the CursorNotFound error code as resumable
     if (error.code === MONGODB_ERROR_CODES.CursorNotFound) {

test/integration/change-streams/change_stream.test.ts

@@ -1,4 +1,5 @@
 import { strict as assert } from 'assert';
+import { UUID } from 'bson';
 import { expect } from 'chai';
 import { on, once } from 'events';
 import { gte, lt } from 'semver';
@@ -14,6 +15,7 @@ import {
   type CommandStartedEvent,
   type Db,
   isHello,
+  LEGACY_HELLO_COMMAND,
   Long,
   MongoAPIError,
   MongoChangeStreamError,
@@ -45,6 +47,19 @@ const pipeline = [
   { $addFields: { comment: 'The documentKey field has been projected out of this document.' } }
 ];
 
+async function forcePrimaryStepDown(client: MongoClient) {
+  await client
+    .db('admin')
+    .command({ replSetFreeze: 0 }, { readPreference: ReadPreference.SECONDARY });
+  await client
+    .db('admin')
+    .command({ replSetStepDown: 15, secondaryCatchUpPeriodSecs: 10, force: true });
+
+  // wait for secondary to become primary but also allow previous primary to become next primary
+  // in subsequent test runs
+  await sleep(15_000);
+}
+
 describe('Change Streams', function () {
   let client: MongoClient;
   let collection: Collection;
@@ -2003,9 +2018,11 @@ describe('Change Streams', function () {
 
 describe('ChangeStream resumability', function () {
   let client: MongoClient;
+  let utilClient: MongoClient;
   let collection: Collection;
   let changeStream: ChangeStream;
   let aggregateEvents: CommandStartedEvent[] = [];
+  let appName: string;
 
   const changeStreamResumeOptions: ChangeStreamOptions = {
     fullDocument: 'updateLookup',
@@ -2055,22 +2072,36 @@ describe('ChangeStream resumability', function () {
   beforeEach(async function () {
     const dbName = 'resumabilty_tests';
     const collectionName = 'foo';
-    const utilClient = this.configuration.newClient();
+
+    utilClient = this.configuration.newClient();
+
     // 3.6 servers do not support creating a change stream on a database that doesn't exist
     await utilClient
       .db(dbName)
       .dropDatabase()
       .catch(e => e);
     await utilClient.db(dbName).createCollection(collectionName);
-    await utilClient.close();
 
-    client = this.configuration.newClient({ monitorCommands: true });
+    // we are going to switch primary in tests and cleanup of failpoints is difficult,
+    // so generating unique appname instead of cleaning for each test is an easier solution
+    appName = new UUID().toString();
+
+    client = this.configuration.newClient(
+      {},
+      {
+        monitorCommands: true,
+        serverSelectionTimeoutMS: 10_000,
+        heartbeatFrequencyMS: 5_000,
+        appName: appName
+      }
+    );
     client.on('commandStarted', filterForCommands(['aggregate'], aggregateEvents));
     collection = client.db(dbName).collection(collectionName);
   });
 
   afterEach(async function () {
     await changeStream.close();
+    await utilClient.close();
     await client.close();
     aggregateEvents = [];
   });
@@ -2228,6 +2259,38 @@ describe('ChangeStream resumability', function () {
           expect(changeStream.closed).to.be.true;
         });
       });
+
+      context('when the error is not a server error', function () {
+        it(
+          'should resume on ServerSelectionError',
+          { requires: { topology: ['replicaset'] } },
+          async function () {
+            changeStream = collection.watch([]);
+            await initIteratorMode(changeStream);
+
+            await collection.insertOne({ a: 1 });
+
+            await utilClient.db('admin').command({
+              configureFailPoint: 'failCommand',
+              mode: 'alwaysOn',
+              data: {
+                failCommands: ['ping', 'hello', LEGACY_HELLO_COMMAND],
+                closeConnection: true,
+                appName: appName
+              }
+            } as FailCommandFailPoint);
+
+            await forcePrimaryStepDown(utilClient);
+
+            const change = await changeStream.next();
+            expect(change).to.containSubset({ operationType: 'insert', fullDocument: { a: 1 } });
+
+            expect(aggregateEvents).to.have.lengthOf(2);
+            const [e1, e2] = aggregateEvents;
+            expect(e1.address).to.not.equal(e2.address);
+          }
+        );
+      });
     });
 
     context('#hasNext', function () {
@@ -2541,6 +2604,37 @@ describe('ChangeStream resumability', function () {
           expect(changeStream.closed).to.be.true;
         });
       });
+
+      context('when the error is not a server error', function () {
+        it(
+          'should resume on ServerSelectionError',
+          { requires: { topology: ['replicaset'] } },
+          async function () {
+            changeStream = collection.watch([]);
+            await initIteratorMode(changeStream);
+
+            await collection.insertOne({ a: 1 });
+
+            await utilClient.db('admin').command({
+              configureFailPoint: 'failCommand',
+              mode: 'alwaysOn',
+              data: {
+                failCommands: ['ping', 'hello', LEGACY_HELLO_COMMAND],
+                closeConnection: true,
+                appName: appName
+              }
+            } as FailCommandFailPoint);
+            await forcePrimaryStepDown(utilClient);
+
+            const change = await changeStream.tryNext();
+            expect(change).to.containSubset({ operationType: 'insert', fullDocument: { a: 1 } });
+
+            expect(aggregateEvents).to.have.lengthOf(2);
+            const [e1, e2] = aggregateEvents;
+            expect(e1.address).to.not.equal(e2.address);
+          }
+        );
+      });
     });
 
     context('#asyncIterator', function () {
@@ -2677,6 +2771,41 @@ describe('ChangeStream resumability', function () {
           }
         });
       });
+
+      context('when the error is not a server error', function () {
+        it(
+          'should resume on ServerSelectionError',
+          { requires: { topology: ['replicaset'] } },
+          async function () {
+            changeStream = collection.watch([]);
+            await initIteratorMode(changeStream);
+            const changeStreamIterator = changeStream[Symbol.asyncIterator]();
+
+            await collection.insertOne({ a: 1 });
+
+            await utilClient.db('admin').command({
+              configureFailPoint: 'failCommand',
+              mode: 'alwaysOn',
+              data: {
+                failCommands: ['ping', 'hello', LEGACY_HELLO_COMMAND],
+                closeConnection: true,
+                appName: appName
+              }
+            } as FailCommandFailPoint);
+            await forcePrimaryStepDown(utilClient);
+
+            const change = await changeStreamIterator.next();
+            expect(change.value).to.containSubset({
+              operationType: 'insert',
+              fullDocument: { a: 1 }
+            });
+
+            expect(aggregateEvents).to.have.lengthOf(2);
+            const [e1, e2] = aggregateEvents;
+            expect(e1.address).to.not.equal(e2.address);
+          }
+        );
+      });
     });
   });
 
@@ -2866,6 +2995,50 @@ describe('ChangeStream resumability', function () {
         expect(changeStream.closed).to.be.true;
       });
     });
+
+    context('when the error is not a server error', function () {
+      it(
+        'should resume on ServerSelectionError',
+        { requires: { topology: ['replicaset'] } },
+        async function () {
+          changeStream = collection.watch([]);
+
+          const changes = on(changeStream, 'change');
+          await once(changeStream.cursor, 'init');
+
+          await collection.insertOne({ a: 1 });
+
+          const change = await changes.next();
+          expect(change.value[0]).to.containSubset({
+            operationType: 'insert',
+            fullDocument: { a: 1 }
+          });
+
+          await utilClient.db('admin').command({
+            configureFailPoint: 'failCommand',
+            mode: 'alwaysOn',
+            data: {
+              failCommands: ['ping', 'hello', LEGACY_HELLO_COMMAND],
+              closeConnection: true,
+              appName: appName
+            }
+          } as FailCommandFailPoint);
+          await forcePrimaryStepDown(utilClient);
+
+          await collection.insertOne({ a: 2 });
+
+          const change2 = await changes.next();
+          expect(change2.value[0]).to.containSubset({
+            operationType: 'insert',
+            fullDocument: { a: 2 }
+          });
+
+          expect(aggregateEvents).to.have.lengthOf(2);
+          const [e1, e2] = aggregateEvents;
+          expect(e1.address).to.not.equal(e2.address);
+        }
+      );
+    });
   });
 
   it(