Adjust default values for replicas and partitions

Requests to create topics will fail if you supply assignments and
partitions/replicas together. If you don't supply a value for
partitions/replicas at all, default values of 1 will be used which also
leads to topic creation failures. Here, the default values for the two
settings are changed to -1 so that topic creations do not fail due to
conflicting settings. Furthermore, this has the benefit of using the
default values set inside the Kafka cluster.

Related:
- tulios/kafkajs#1305

Author: lp247

src/clients/admin/admin.ts

@@ -444,8 +444,9 @@ export class Admin extends Base<AdminOptions> {
   }
 
   #createTopics (options: CreateTopicsOptions, callback: CallbackWithPromise<CreatedTopic[]>): void {
-    const numPartitions = options.partitions ?? 1
-    const replicationFactor = options.replicas ?? 1
+    // -1 is required if manual assignments are used. If no manual assignments are used, -1 will default to broker settings.
+    const numPartitions = options.partitions ?? -1
+    const replicationFactor = options.replicas ?? -1
     const assignments: CreateTopicsRequestTopicAssignment[] = []
     const configs = options.configs ?? []
 

test/clients/admin/admin.test.ts

@@ -439,8 +439,6 @@ test('createTopics using assignments', async t => {
   // Create a topic with a single partition - leader will be automatically assigned
   const created = await admin.createTopics({
     topics: [topicName],
-    partitions: -1,
-    replicas: -1,
     assignments: brokerIds.map((brokerId, i) => ({ partition: i, brokers: [brokerId] }))
   })