My ptw doesn't "watch" subdirectories

[andb0t]

In my python project, I use ptw. My project is structured as follows:

.
├── Pipfile
├── Pipfile.lock
├── README.md
├── call_api.py
├── data
│   └── Iris.csv
├── pytest.ini
├── src
│   ├── __init__.py
│   ├── accept_real_data.py
│   ├── generate_synth_data.py
│   ├── main.py
│   └── return_synth_data.py
└── tests
    ├── __init__.py
    └── src
        ├── __init__.py
        └── test_generate_synth_data.py

When I execute ptw in the main directory, the tests in test_generate_synth_data.py are only executed when I change the call_api.py, but not when I change e.g. the generate_synth_data.py or a test in tests. call_api.py imports all files in src. I thought that ptw would "follow" imports or at least "find" all .py files in subdirectories? Am I missing something?

Edit: I accidently hit ctrl+enter too early, thus posting an empty issue at first.