tests: metrics tests fail when `PYTHONWARNINGS="ignore"`

[michaelbrewer]

What were you trying to accomplish?

Run make test when PYTHONWARNINGS="ignore"

Expected Behavior

Test should pass

Current Behavior

_____________________________________________________________________________________________________ test_log_metrics_decorator_no_metrics_warning _____________________________________________________________________________________________________

dimensions = [{'name': 'test_dimension', 'value': 'test'}, {'name': 'test_dimension_2', 'value': 'test'}], namespace = 'test_namespace', service = 'test_service'

    def test_log_metrics_decorator_no_metrics_warning(dimensions, namespace, service):
        # GIVEN Metrics is initialized
        my_metrics = Metrics(namespace=namespace, service=service)
    
        # WHEN using the log_metrics decorator and no metrics have been added
        @my_metrics.log_metrics
        def lambda_handler(evt, context):
            pass
    
        # THEN it should raise a warning instead of throwing an exception
        with warnings.catch_warnings(record=True) as w:
            lambda_handler({}, {})
>           assert len(w) == 1
E           assert 0 == 1
E             +0
E             -1

tests/functional/test_metrics.py:555: AssertionError

Possible Solution

Temp set warnings.simplefilter("default")

• PR: chore(metrics): fix tests when warnings are disabled #994

Steps to Reproduce (for bugs)

1. export PYTHONWARNINGS="ignore"
2. make test

Environment

• Powertools version used:
• Packaging format (Layers, PyPi):
• AWS Lambda function runtime:
• Debugging logs

[heitorlessa]

@michaelbrewer could you provide more details about this issue before we merge? How did you run into it since this flag isn't set by default?

Looking at the docs, it seems we should be doing this for all utilities not just metrics: https://docs.python.org/3/library/warnings.html#overriding-the-default-filter

[michaelbrewer]

i was trying to disabled some setup issues with poetry on my m1 mac and it prints out warnings.

[michaelbrewer]

@heitorlessa this is based on pythons recommended way for testing warnings:

import warnings

def fxn():
    warnings.warn("deprecated", DeprecationWarning)

with warnings.catch_warnings(record=True) as w:
    # Cause all warnings to always be triggered.
    warnings.simplefilter("always")
    # Trigger a warning.
    fxn()
    # Verify some things
    assert len(w) == 1
    assert issubclass(w[-1].category, DeprecationWarning)
    assert "deprecated" in str(w[-1].message)