Python moto fails to match valid Eventbridge pattern - aws-event-bridge

Question

I have a couple of Eventbridge events ({"root": "child"} and {"root": ["child"]}) which I want to match against pattern {"root": ["child"]}.
Both these matches are valid according to aws events test-event-pattern -
aws events test-event-pattern --event '{"id": 1234567890, "source": "my-source", "detail-type": "my-detail-type", "detail": {"root": "child"}, "account": 1234567890, "region": "eu-west-1", "time": "1970-12-20T20:00:00Z"}' --event-pattern '{"source": ["my-source"], "detail": {"root": ["child"]}}' --output text
True
aws events test-event-pattern --event '{"id": 1234567890, "source": "my-source", "detail-type": "my-detail-type", "detail": {"root": ["child"]}, "account": 1234567890, "region": "eu-west-1", "time": "1970-12-20T20:00:00Z"}' --event-pattern '{"source": ["my-source"], "detail": {"root": ["child"]}}' --output text
True
But I can only get the former pattern to match when I use moto to mock the message flow (script at bottom)
% python scripts/demo/moto_events/test_moto.py
{"root": "child"} -> True
{"root": ["child"]} -> False
Have I made a mistake here or is moto events behaviour diverging from AWS Eventbridge ?
TIA
cc #BertBlommers
ps using moto 2.0.11
from moto import mock_events, mock_sqs
from botocore.exceptions import ClientError
import boto3, copy, json, yaml
EventBase=yaml.safe_load("""
Source: my-source
DetailType: my-detail-type
""")
Statement=yaml.safe_load("""
Effect: Allow
Principal:
Service: events.amazonaws.com
Action: "sqs:SendMessage"
Resource: "*"
""")
def drain_sqs(sqs, queueurl, nmax=100):
messages, count = [], 0
while True:
resp=sqs.receive_message(QueueUrl=queueurl)
if ("Messages" not in resp or
count > nmax):
break
messages+=resp["Messages"]
count+=1
return messages
#mock_events
#mock_sqs
def test_event_pattern(detail,
eventbase=EventBase,
statement=Statement):
events, sqs, = boto3.client("events"), boto3.client("sqs")
policy=json.dumps({"Version": "2012-10-17",
"Statement": [statement]})
queue=sqs.create_queue(QueueName="my-queue",
Attributes={"Policy": policy})
queueurl=queue["QueueUrl"]
queueattrs=sqs.get_queue_attributes(QueueUrl=queueurl)["Attributes"]
queuearn=queueattrs["QueueArn"]
pattern={"detail": detail["pattern"]}
events.put_rule(Name="my-rule",
State="ENABLED",
EventPattern=json.dumps(pattern))
events.put_targets(Rule="my-rule",
Targets=[{"Id": "my-target-id",
"Arn": queuearn}])
event=copy.deepcopy(eventbase)
event["Detail"]=json.dumps(detail["event"])
events.put_events(Entries=[event])
return drain_sqs(sqs, queue["QueueUrl"])
if __name__=="__main__":
try:
for detail in [{"event": {"root": "child"},
"pattern": {"root": ["child"]}},
{"event": {"root": ["child"]},
"pattern": {"root": ["child"]}}]:
messages=test_event_pattern(detail)
print ("%s -> %s" % (json.dumps(detail["event"]),
bool(len(messages))))
except ClientError as error:
print ("Error: %s" % str(error))