KafkaJS.Consumer: unpause function returned by consumer.pause() incorrectly unpauses all partitions

[justjake]

Environment Information

• OS [e.g. Mac, Arch, Windows 10]: macOS 14.5 (23F79)
• Node Version [e.g. 8.2.1]: v18.17.0
• NPM Version [e.g. 5.4.2]: 9.6.7
• C++ Toolchain [e.g. Visual Studio, llvm, g++]: Xcode 14
• confluent-kafka-javascript version [e.g. 2.3.3]: "@confluentinc/kafka-javascript": "0.1.16-devel"

Steps to Reproduce

There is a logic error in the Consumer.pause() method. See the WARNING and ERROR comments I left below.

  pause(topics) {
    if (this.#state !== ConsumerState.CONNECTED) {
      throw new error.KafkaJSError('Pause can only be called while connected.', { code: error.ErrorCodes.ERR__STATE });
    }

    for (let topic of topics) {
      if (typeof topic.topic !== 'string') {
        throw new error.KafkaJSError('Topic must be a string.', { code: error.ErrorCodes.ERR__INVALID_ARG });
      }

      if (!topic.partitions) {
        // WARNING: incorrect passing [{ topic: string, partition: number }] will result
        // in unpausing all assigned partitions for that topic!
        topic.partitions = this.#getAllAssignedPartition(topic.topic);
      }
    }
    
    // ERROR: topics was Array<{ topic: string, partitions: number[] }>,
    // but now is Array<{ topic: string, partition: number }> since it's been flattened
    // Recommendation: don't change the types of local variables
    topics = this.#flattenTopicPartitions(topics);
    if (topics.length === 0) {
      return;
    }
    this.#internalClient.pause(topics);

    /* Mark the messages in the cache as stale, runInternal* will deal with
     * making it unusable. */
    this.#messageCache.markStale(topics);

    /* If anyone's using eachBatch, mark the batch as stale. */
    topics.map(partitionKey)
      .filter(key => this.#topicPartitionToBatchPayload.has(key))
      .forEach(key => this.#topicPartitionToBatchPayload.get(key)._stale = true);

    topics.map(JSON.stringify).forEach(topicPartition => this.#pausedPartitions.add(topicPartition));

    // ERROR: this.resume(topics) expects Array<{ topic: string, partitions: number[] }>,
    // but is now Array<{ topic: string, partition: number }> since it's been flattened
    // Given the branch `if (!topic.partitions)` above, we expect to unpause all partitions
    return () => this.resume(topics);
  }

[milindl]

Closing with release 0.1.17-devel