Stepfunction describe executions returns a double encoded string

[Lucas Spencer-Scheilling]

Issue

When running describe_execution as follows, the result is a string not the expected dictionary

@mock_aws
def test_a(self):
    client = boto3.client("stepfunctions")
    sf = client.create_state_machine(
        name="name",
        definition="definition",
        roleArn=f"arn:aws:iam::{DEFAULT_ACCOUNT_ID}:role/unknown_sf_role",
    )
    step_function_arn = sf["stateMachineArn"]
    client.start_execution(stateMachineArn=step_function_arn, input=json.dumps({"test": "content"}))
    executions = client.list_executions(
        stateMachineArn=step_function_arn,
        statusFilter="RUNNING",
        maxResults=100,
    )
    for execution in executions["executions"]:
        execution_input = json.loads(client.describe_execution(executionArn=execution["executionArn"])["input"])
        assert execution_input == {"test": "content"}

execution_input would be equal to '{"test": "content"}' not the expected {"test": "content"}

Versions affected

Only 5.0.4 when using python mocks

[rafcio19]

@lscheilling I took a look at the documentation and input should be a str, not a dict - so the moto implementation is correct.

https://docs.aws.amazon.com/step-functions/latest/apireference/API_DescribeExecution.html
https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/stepfunctions/client/describe_execution.html

[Lucas Spencer-Scheilling]

@lscheilling I took a look at the documentation and input should be a str, not a dict - so the moto implementation is correct.

https://docs.aws.amazon.com/step-functions/latest/apireference/API_DescribeExecution.html https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/stepfunctions/client/describe_execution.html

This was not my issue with this, the output was always a string, but the output was after being run through json.loads was still a string, so we would be getting '"{"test": "content"}"' for input instead of '{"test": "content"}'

If you switch between moto versions 5.0.3 and 5.0.4 on this test case you should be able to see the differing behaviours

[Bert Blommers]

Hi @lscheilling, thanks for raising this. We introduced a new option to execute state machines in 5.0.4, and it looks like that indeed broke something in the existing implementation.

I'll open a PR with a fix now.