python/ci: add Python type check

We started to use more and more type hints in our Python code, especially
in most helper functions. This change doesn't force you to write type hints
to every Python code, but enforces correct type hints when they are already
provided.

Typings are a great developer experience improvement in IDEs with Python
support.

On-behalf-of: SAP philipp.schuster@sap.com
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>

Author: phip1611

.github/workflows/build.yml

@@ -39,6 +39,8 @@ jobs:
         run: nix build -L .#checks.x86_64-linux.pythonFormat
       - name: Check Python Lints
         run: nix build -L .#checks.x86_64-linux.pythonLint
+      - name: Check Python Types
+        run: nix build -L .#checks.x86_64-linux.pythonTypes
       - name: Check Spelling
         run: nix build -L .#checks.x86_64-linux.typos
       # Run all in case we forgot to add a fine-grained job.
@@ -47,7 +49,6 @@ jobs:
           nix build -L .#checks.x86_64-linux.all
           # Run all other flake-wide checks
           # TODO add once we have quicker CI runners
-          # This
           # nix flake check
       - name: Eval Default Test Suite
         run: nix eval -L .#tests.x86_64-linux.default.driver

flake.nix

@@ -141,6 +141,15 @@
                   ruff check ./tests
                   mkdir $out
                 '';
+            pythonTypes =
+              pkgs.runCommand "python-types"
+                {
+                  nativeBuildInputs = with pkgs; [ pyright ];
+                }
+                ''
+                  pyright ${cleanSrc}/tests
+                  mkdir $out
+                '';
             typos =
               pkgs.runCommand "spellcheck"
                 {
@@ -167,6 +176,7 @@
               deadnix
               pythonFormat
               pythonLint
+              pythonTypes
               typos
               ;
             default = all;

tests/testscript.py

@@ -6,6 +6,8 @@
 import unittest
 import weakref
 
+# pyright: reportPossiblyUnboundVariable=false
+
 # Following is required to allow proper linting of the python code in IDEs.
 # Because certain functions like start_all() and certain objects like computeVM
 # or other machines are added by Nix, we need to provide certain stub objects
@@ -85,7 +87,8 @@ def __init__(self, command, machine):
         :param machine: Virtual machine to send the command from
         :type machine: Machine
         """
-        self._finilizer = weakref.finalize(self, command, machine)
+
+        self._finilizer = weakref.finalize(self, command, machine)  # pyright: ignore[reportCallIssue]
 
     def __enter__(self):
         return self

tests/testscript_long_migration_with_load.py

@@ -1,6 +1,8 @@
 import time
 import unittest
 
+# pyright: reportPossiblyUnboundVariable=false
+
 # Following is required to allow proper linting of the python code in IDEs.
 # Because certain functions like start_all() and certain objects like computeVM
 # or other machines are added by Nix, we need to provide certain stub objects