Adds type checks via pyright to CI (#2477)

* Adds type checks via `pyright` to CI

* Move developer instructions into CONTRIBUTING.md

* black formatting

* Explicit list of strictly checked files

Co-authored-by: Ilya Kamen <[email protected]>

.github/workflows/lint_python.yml

@@ -13,3 +13,22 @@ jobs:
       - run: pytest . || true
       - run: pytest --doctest-modules . || true
       - run: shopt -s globstar && pyupgrade --py36-plus **/*.py || true
+
+  pyright:
+    name: Check types with pyright
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-platform: [ "Linux", "Windows", "Darwin" ]
+        python-version: [ "3.6", "3.7", "3.8", "3.9" ]
+      fail-fast: false
+    env:
+      PYRIGHT_VERSION: 1.1.183
+    steps:
+      - uses: actions/checkout@v2
+      - uses: jakebailey/pyright-action@v1
+        with:
+          version: ${{ env.PYRIGHT_VERSION }}
+          python-platform: ${{ matrix.python-platform }}
+          python-version: ${{ matrix.python-version }}
+          no-comments: ${{ matrix.python-version != '3.9' || matrix.python-platform != 'Linux' }}  # Having each job create the same comment is too noisy.

CONTRIBUTING.md

@@ -16,3 +16,19 @@ If you wish to make a Gym environment, follow the instructions in [Creating Envi
 
 
 Edit July 27, 2021: Please see https://github.com/openai/gym/issues/2259 for new contributing standards
+
+# Development
+This section contains technical instructions & hints for the contributors.
+
+## Type checking
+The project uses `pyright` to check types. 
+To type check locally, install pyright per official [instructions](https://github.com/microsoft/pyright#command-line). 
+It's configuration lives under a section of `pyproject.toml`. It includes list of files currently supporting type checks. Use `pyright` CLI command to launch type checks.
+
+### Adding typing to more modules and packages
+
+If you would like to add typing to a module in the project, 
+add the path to the file(s) in the include section 
+(pyproject.toml -> [tool.pyright] -> include). 
+Then you can run `pyright` to see list of type problems in the newly added file, and fix them.
+

gym/logger.py

@@ -1,5 +1,6 @@
 import sys
 import warnings
+from typing import Optional, Type
 
 from gym.utils import colorize
 
@@ -9,42 +10,47 @@
 ERROR = 40
 DISABLED = 50
 
-MIN_LEVEL = 30
+min_level = 30
 
 
-def set_level(level):
+def set_level(level: int) -> None:
     """
     Set logging threshold on current logger.
     """
-    global MIN_LEVEL
-    MIN_LEVEL = level
+    global min_level
+    min_level = level
 
 
-def debug(msg, *args):
-    if MIN_LEVEL <= DEBUG:
+def debug(msg: str, *args: object):
+    if min_level <= DEBUG:
         print(f"DEBUG: {msg % args}", file=sys.stderr)
 
 
-def info(msg, *args):
-    if MIN_LEVEL <= INFO:
+def info(msg: str, *args: object):
+    if min_level <= INFO:
         print(f"INFO: {msg % args}", file=sys.stderr)
 
 
-def warn(msg, *args, category=None, stacklevel=1):
-    if MIN_LEVEL <= WARN:
+def warn(
+    msg: str,
+    *args: object,
+    category: Optional[Type[Warning]] = None,
+    stacklevel: int = 1,
+):
+    if min_level <= WARN:
         warnings.warn(
             colorize(f"WARN: {msg % args}", "yellow"),
             category=category,
             stacklevel=stacklevel + 1,
         )
 
 
-def deprecation(msg, *args):
+def deprecation(msg: str, *args: object):
     warn(msg, *args, category=DeprecationWarning, stacklevel=2)
 
 
-def error(msg, *args):
-    if MIN_LEVEL <= ERROR:
+def error(msg: str, *args: object):
+    if min_level <= ERROR:
         print(colorize(f"ERROR: {msg % args}", "red"), file=sys.stderr)
 
 

pyproject.toml

@@ -0,0 +1,12 @@
+[tool.pyright]
+
+include = ["gym/version.py", "gym/logger.py"]
+exclude = [
+    "**/node_modules",
+    "**/__pycache__",
+]
+strict = ["gym/version.py", "gym/logger.py"]
+
+reportMissingImports = true
+reportMissingTypeStubs = false
+verboseOutput = true