feat: Add mypy type checking

.pre-commit-config.yaml

@@ -40,5 +40,13 @@ repos:
       - id: poetry-check
         args: ['-C', 'api']
 
+  - repo: local
+    hooks:
+      - id: mypy-check
+        name: mypy check
+        entry: bash -c "cd api && poetry run python scripts/mypy_check.py $(git diff --name-only --cached -- '*.py')"
+        language: system
+        types: [python]
+
 ci:
   autoupdate_commit_msg: 'ci: pre-commit autoupdate'

api/app/settings/common.py

@@ -543,7 +543,9 @@
 
 SECURE_REDIRECT_EXEMPT = env.list("DJANGO_SECURE_REDIRECT_EXEMPT", default=[])
 SECURE_REFERRER_POLICY = env.str("DJANGO_SECURE_REFERRER_POLICY", default="same-origin")
-SECURE_CROSS_ORIGIN_OPENER_POLICY = env.str("DJANGO_SECURE_CROSS_ORIGIN_OPENER_POLICY", default="same-origin")
+SECURE_CROSS_ORIGIN_OPENER_POLICY = env.str(
+    "DJANGO_SECURE_CROSS_ORIGIN_OPENER_POLICY", default="same-origin"
+)
 SECURE_SSL_HOST = env.str("DJANGO_SECURE_SSL_HOST", default=None)
 SECURE_SSL_REDIRECT = env.bool("DJANGO_SECURE_SSL_REDIRECT", default=False)
 

api/pyproject.toml

@@ -99,6 +99,16 @@ skip = ['migrations', '.venv', '.direnv']
 addopts = ['--ds=app.settings.test', '-vvvv', '-p', 'no:warnings']
 console_output_style = 'count'
 
+[tool.mypy]
+exclude = "^(tests/)$"
+plugins = ["mypy_django_plugin.main"]
+
+[tool.django-stubs]
+django_settings_module = "app.settings.local"
+
+[tool.drf-stubs]
+enabled = true
+
 [tool.poetry]
 name = "flagsmith-api"
 version = "2.68.0"
@@ -161,7 +171,7 @@ django-ordered-model = "~3.4.1"
 django-ses = "~3.5.0"
 django-axes = "~5.32.0"
 pydantic = "^2.3.0"
-pyngo = "~2.0.1"
+pyngo = "~2.2.1"
 flagsmith = "^3.6.0"
 python-gnupg = "^0.5.1"
 django-redis = "^5.4.0"
@@ -219,6 +229,10 @@ requests-mock = "^1.11.0"
 django-extensions = "^3.2.3"
 pdbpp = "^0.10.3"
 mypy-boto3-dynamodb = "^1.33.0"
+mypy = "^1.11.2"
+django-stubs = "~5.1.1"
+djangorestframework-stubs = "~3.14.0"
+boto3-stubs = "~1.35.67"
 
 [build-system]
 requires = ["poetry-core>=1.5.0"]

api/scripts/mypy_check.py

@@ -0,0 +1,73 @@
+import re
+import subprocess
+import sys
+from pathlib import Path
+
+
+def main() -> None:
+    baseline_path = Path("scripts/mypy_baseline.txt")
+    if not baseline_path.exists():
+        print("Baseline file not found. Run mypy and create mypy_baseline.txt first.")
+        sys.exit(1)
+
+    # Run mypy and capture output
+    files_to_check = [f"../{filename}" for filename in sys.argv[1:]]
+    command = [
+        "poetry",
+        "run",
+        "mypy",
+        "--config-file",
+        "pyproject.toml",
+    ] + files_to_check
+
+    result = subprocess.run(
+        command,
+        capture_output=True,
+        text=True,
+    )
+
+    # Mypy found no issues for the targeted file
+    if result.returncode == 0:
+        print(result.stdout.strip())
+        sys.exit(0)
+
+    # Mypy failed in some other way other than listing failing file lines
+    if result.returncode != 1:
+        print(
+            f"Error running mypy with return code {result.returncode} and error:",
+            result.stderr,
+        )
+        print(result.stdout.strip())
+        sys.exit(1)
+
+    current_output = result.stdout.strip().splitlines()
+
+    with open(baseline_path, "r") as f:
+        baseline = set(line.strip() for line in f if line.strip())
+
+    # Detect new errors and remove information line filtering out third party packages
+    current_errors = {line for line in current_output if "site-packages" not in line}
+    new_errors = current_errors - baseline
+    pattern = r"Found (\d+) errors in (\d+) files \(checked (\d+) source files\)"
+    removal = None
+
+    for error in new_errors:
+        has_match = re.match(pattern, error)
+        if has_match:
+            removal = error
+            break
+
+    if removal:
+        new_errors.remove(removal)
+
+    if new_errors:
+        print("New mypy errors detected:")
+        print("\n".join(new_errors))
+        sys.exit(1)
+
+    print("No new mypy errors detected.")
+    sys.exit(0)
+
+
+if __name__ == "__main__":
+    main()