test: add unittest to run mypy

New unittest file consists of two tests. Both
run mypy, but one does so with arguments that are
expected to allow the test to pass. The other does
not provide those arguments and is expected to fail.
The expected failure is intentional, to serve as
an ongoing reminder to try to 1) move towards having
strict typing in the codebase and to 2) not
add any additional errors/warnings in the meantime.

Separated requirements into runtime (requirements.txt)
and additional development (requirements-dev.txt).
Modified devcontainer and workflow to reflect the
change.

.devcontainer/devcontainer.json

@@ -12,7 +12,7 @@
 	// "forwardPorts": [],
 
 	// Use 'postCreateCommand' to run commands after the container is created.
-	"postCreateCommand": "pip3 install --user -r requirements.txt"
+	"postCreateCommand": "pip3 install --user -r requirements.txt -r requirements-dev.txt"
 
 	// Configure tool-specific properties.
 	// "customizations": {},

.github/workflows/ci.yml

@@ -13,6 +13,6 @@ jobs:
       - name: "Install test dependencies"
         run: |
           python -m pip install --upgrade pip
-          pip install -r requirements.txt
+          pip install -r requirements.txt -r requirements-dev.txt
       - name: "Run tests"
         run: python -m pytest

requirements-dev.txt

@@ -0,0 +1,4 @@
+pytest==8.3.3
+mypy==1.13.0
+mypy-extensions==1.0.0
+types-requests==2.32.0.20241016

requirements.txt

@@ -1,3 +1,2 @@
 requests==2.32.3
-ruamel.yaml==0.18.6
-pytest==8.3.3
+ruamel.yaml==0.18.6

tests/test_syntax.py

@@ -0,0 +1,39 @@
+# based on https://gist.github.com/bbarker/4ddf4a1c58ae8465f3d37b6f2234a421
+
+import os
+import subprocess
+import sys
+import unittest
+from typing import List
+
+
+class MyPyTest(unittest.TestCase):
+
+    def __call_mypy__(self, args, files):
+        result: int = subprocess.call(self.base_mypy_call + args + files, env=os.environ, cwd=self.pypath)
+        self.assertEqual(result, 0, '')
+
+    def test_run_mypy_app(self):
+        mypy_args: List[str] = [
+            "--disable-error-code", "var-annotated"
+        ]
+        self.__call_mypy__(mypy_args, ["main.py"])
+
+    # Run test again, but without disabling any error codes.
+    # This is expected to fail, but we intentionally keep this test around to
+    #   1) try not to add any more errors to what's already in the baseline
+    #   2) as a reminder to try to move the codebase towards having type checking eventually
+    @unittest.expectedFailure
+    def test_run_strict_mypy_app(self):
+        mypy_args: List[str] = []
+        self.__call_mypy__(mypy_args, ["main.py"])
+
+    def __init__(self, *args, **kwargs) -> None:
+        super(MyPyTest, self).__init__(*args, **kwargs)
+        my_env = os.environ.copy()
+        self.pypath: str = my_env.get("PYTHONPATH", os.getcwd())
+        self.base_mypy_call: List[str] = [sys.executable, "-m", "mypy", "--ignore-missing-imports"]
+
+
+if __name__ == '__main__':
+    unittest.main()