fix(NODE-5925): driver throws error when non-read operation in a transaction has a ReadPreferenceMode other than 'primary' (#4075)

Author: aditi-khare-mongoDB

src/operations/execute_operation.ts

@@ -119,7 +119,14 @@ export async function executeOperation<
   const readPreference = operation.readPreference ?? ReadPreference.primary;
   const inTransaction = !!session?.inTransaction();
 
-  if (inTransaction && !readPreference.equals(ReadPreference.primary)) {
+  const hasReadAspect = operation.hasAspect(Aspect.READ_OPERATION);
+  const hasWriteAspect = operation.hasAspect(Aspect.WRITE_OPERATION);
+
+  if (
+    inTransaction &&
+    !readPreference.equals(ReadPreference.primary) &&
+    (hasReadAspect || operation.commandName === 'runCommand')
+  ) {
     throw new MongoTransactionError(
       `Read preference in a transaction must be primary, not: ${readPreference.mode}`
     );
@@ -177,8 +184,6 @@ export async function executeOperation<
     supportsRetryableWrites(server) &&
     operation.canRetryWrite;
 
-  const hasReadAspect = operation.hasAspect(Aspect.READ_OPERATION);
-  const hasWriteAspect = operation.hasAspect(Aspect.WRITE_OPERATION);
   const willRetry = (hasReadAspect && willRetryRead) || (hasWriteAspect && willRetryWrite);
 
   if (hasWriteAspect && willRetryWrite) {

src/sessions.ts

@@ -194,7 +194,7 @@ export class ClientSession extends TypedEventEmitter<ClientSessionEvents> {
 
     this.operationTime = undefined;
     this.owner = options.owner;
-    this.defaultTransactionOptions = Object.assign({}, options.defaultTransactionOptions);
+    this.defaultTransactionOptions = { ...options.defaultTransactionOptions };
     this.transaction = new Transaction();
   }
 

test/integration/transactions/transactions.spec.test.ts

@@ -4,8 +4,6 @@ import { loadSpecTests } from '../../spec';
 import { runUnifiedSuite } from '../../tools/unified-spec-runner/runner';
 
 const SKIPPED_TESTS = [
-  // TODO(NODE-5925) - secondary read preference not allowed in transactions.
-  'readPreference inherited from defaultTransactionOptions',
   // TODO(NODE-5924) - Fix modification of readConcern object post message send.
   'readConcern local in defaultTransactionOptions',
   'defaultTransactionOptions override client options',
@@ -17,7 +15,7 @@ const SKIPPED_TESTS = [
 describe('Transactions Spec Unified Tests', function () {
   runUnifiedSuite(loadSpecTests(path.join('transactions', 'unified')), test => {
     return SKIPPED_TESTS.includes(test.description)
-      ? 'TODO(NODE-5924/NODE-5925): Skipping failing transaction tests'
+      ? 'TODO(NODE-5924): Skipping failing transaction tests'
       : false;
   });
 });

test/tools/unified-spec-runner/entities.ts

@@ -620,9 +620,8 @@ export class EntitiesMap<E = Entity> extends Map<string, E> {
               WriteConcern.fromOptions(defaultOptions);
           }
           if (defaultOptions.readPreference) {
-            options.defaultTransactionOptions.readPreference = ReadPreference.fromOptions(
-              defaultOptions.readPreference
-            );
+            options.defaultTransactionOptions.readPreference =
+              ReadPreference.fromOptions(defaultOptions);
           }
           if (typeof defaultOptions.maxCommitTimeMS === 'number') {
             options.defaultTransactionOptions.maxCommitTimeMS = defaultOptions.maxCommitTimeMS;