Real SQS throws `There should be at least one SendMessageBatchRequestEntry in the request. (Service: AmazonSQS; Status Code: 400; Error Code: AWS.SimpleQueueService.EmptyBatchRequest;` when there is a send batch of zero size.

This would be useful to mimic inside localstack in order to find these bugs earlier.
import os
import json
import time
import unittest
from localstack.utils import testutil
from localstack.utils.testutil import get_lambda_log_events, get_lambda_log_group_name
from localstack.utils.aws import aws_stack
from localstack.utils.common import short_uid, retry
from .lambdas import lambda_integration
from .test_lambda import TEST_LAMBDA_PYTHON, LAMBDA_RUNTIME_PYTHON36, TEST_LAMBDA_LIBS
TEST_QUEUE_NAME = 'TestQueue'
TEST_POLICY = """
{
  "Version":"2012-10-17",
  "Statement":[
    {
      "Effect": "Allow",
      "Principal": { "AWS": "*" },
      "Action": "sqs:SendMessage",
      "Resource": "'$sqs_queue_arn'",
      "Condition":{
        "ArnEquals":{
        "aws:SourceArn":"'$sns_topic_arn'"
        }
      }
    }