I’m looking to unit test all my AWS Lambda code in my project using pytest. Due to how I have to configure the directory structure to work with infrastructure as code tooling, each Lambda sits within it’s own CloudFormation stack, I’ve got a pretty non-standard directory structure. I’m unable to get pytest to run all tests across all my Lambda functions – ideally I’d like this to work by just running ‘pytest’ in the root directory of the project.

The directory structure is as follows (it’s worth noting that changing the structure is not an option):

- Project_Directory
  - stack1
    - product.template.yaml
    - src
      - lambda1
        - lambda_function.py
        - requirements.txt
    - tests
      - __init__.py
      - test_functions
        - __init__.py
        - test_lambda1.py
  - stack2
    - product.template.yaml
    - src
      - lambda2
        - lambda_function.py
        - requirements.txt
    - tests
      - __init__.py
      - test_functions
        - __init__.py
        - test_lambda2.py
  - conftest.py
  - pytest.ini

Each test_lambda.py file imports from the lambda_function.py file as follows:
from src.lambdax.lambda_function import func1, func2

When only a single stack is in the project directory pytest has no issue picking up the tests. However when a second stack is added pytest fails with the following error:

ModuleNotFoundError: No module named 'tests.test_functions.test_lambda2'

Also, when running pytest directly against each stack directory the tests run with no issue. That is running pytest stack1 and pytest stack2.

Expectation: Running ‘pytest’ from project_directory yields all tests for all lambdas.

I’ve tried adding testpaths = 00-cfn-cdi-basic-lambda 01-cfn-cdi-second-lambda and testpaths = 00-cfn-cdi-basic-lambda/tests 01-cfn-cdi-second-lambda/tests to pytest.ini to no success.

What am I missing here, I’m guessing maybe some module namespace collision but I’m not sure how to resolve it! Any advice on this issue is much appreciated!