$ pip install pytest coverage

$ pip install -e .
This tells pip to find pyproject.toml in the current directory and
install the project in editable or development mode. Editable mode
means that as you make changes to your local code, you’ll only need
 to re-install if you change the metadata about the project, such as its dependencies.

You can observe that the project is now installed with pip list.

run application
$ flask --app flaskr run --debug