mypy fails with @tracer.capture_lambda_handler

[joyofhex]

Using mypy to typecheck code decorated with the @tracer.capture_lambda_handler fails since v1.10.

Expected Behavior

Mypy should not fail with code decorated with the capture_lambda_handler.

Current Behavior

❯ poetry run mypy src
src/handler.py:5: error: Argument 1 to "capture_lambda_handler" of "Tracer" has incompatible type "Callable[[Any, Any], Any]"; expected "Optional[Callable[[Dict[Any, Any], Any, Optional[Dict[Any, Any]]], Any]]"
Found 1 error in 1 file (checked 1 source file)

Possible Solution

First of all, thanks for the incredibly useful library. It has been a pleasure to work with it.

It seems that in commit 11ebcf9 the following change was introduced:

@@ -238,7 +242,7 @@ class Tracer:

     def capture_lambda_handler(
         self,
-        lambda_handler: Callable[[Dict, Any], Any] = None,
+        lambda_handler: Callable[[Dict, Any, Optional[Dict]], Any] = None,
         capture_response: Optional[bool] = None,
         capture_error: Optional[bool] = None,
     ):

This seems to have changed the expected handler signature to have three parameters instead of two, which is causing the sample code to fail. I've worked around this for now by adding a _ignored: Optional[Any] = None parameter to my lambda handler.

Steps to Reproduce (for bugs)

I created a small repo repo (uh) here: https://github.com/joyofhex/repocase-for-powertools

1. clone above repo
2. cd into repo
3. poetry run mypy

Environment

• Powertools version used: 1.13.0
• Packaging format (Layers, PyPi): pypi
• AWS Lambda function runtime: python 3.8

[heitorlessa]

Thanks a lot for raising it @joyofhex, and it's quite timely because we're working to make MyPy compliant for the next release ;-)

Let us know if you find anything else and we keep you posted!

[michaelbrewer]

@joyofhex @heitorlessa i have a fix in for this on #365

So this example will work via MyPy

from aws_lambda_powertools import Tracer

tracer = Tracer()


@tracer.capture_lambda_handler
def handler(event, context):
    return None

[joyofhex]

Oh, excellent. Thanks for taking the time to address this.

[heitorlessa]

Reopening as we will include this in the next minor release, then we can ping you once it's available :)

[michaelbrewer]

@heitorlessa I think we need to something else to mark the modules as PEP 561