Update CONTRIBUTING.md

CONTRIBUTING.md

@@ -1,6 +1,11 @@
 We recommend working on a feature branch and pull request from there.
 
-## Create a feature branch
+## Requirements
+
+- `poetry`,
+- `PyCharm` (recommended).
+
+## Creating a feature branch
 
 Make sure your environment contains all the updated versions of the dependencies.
 
@@ -20,13 +25,11 @@ $ git checkout develop
 $ git fetch origin
 $ git pull
 $ git branch <feature branch name>
-
 ```
 
 ## Before creating the pull request
 
 Make sure the tests and the following linters pass.
-
 From a `poetry` shell (started from an OpenSquirrel checkout):
 
 ```
@@ -35,3 +38,31 @@ $ mypy . --strict
 $ poetry run isort .
 $ poetry run black .
 ```
+
+## Setting the Python interpreter (PyCharm)
+
+You can choose the Python interpreter from the `poetry` environment.
+
+- Go to `Settings` > `Project: OpenSquirrel` > `Python Interpreter`.
+- Click on `Add Interpeter`, and then select `Add Local Interpreter`.
+- Select `Poetry Environment`, and then `Existing environment`.
+- Click on `...` to navigate to the `Interpreter` binary.
+
+## Running/Debugging tests (PyCharm)
+
+To run/debug all tests:
+
+- Right-click on the `test` folder of the Project tree.
+- Click `Run 'pytest' in test` or `Debug 'pytest' in test`.
+
+This will also create a `Run/Debug Configuration`.
+
+### Troubleshooting
+
+If breakpoints are not hit during debugging:
+
+- Go to `Run/Debug Configurations`.
+- Add `--no-cov` in the `Additional arguments` text box.
+
+This issue may be due to the code coverage module _hijacking_ the tracing mechanism
+(check [this link](https://stackoverflow.com/a/56235965/260313) for a more detailed explanation).