Add support for type checks and type annotations

fixes #164 

* Add mypy to dev dependencies
* Add basic mypy configuration to pyproject.toml
* Add mypy target(s) to noxfile
* Add type annotations to git script
* Add type annotations to version_check script/module
* Fix type annotations in links script/module
* Add various type annotations and add pyodbc typeshed
* Bump version to 3.1.7

noxfile.py

@@ -11,12 +11,25 @@
 SCRIPTS = PROJECT_ROOT / "scripts"
 sys.path.append(f"{SCRIPTS}")
 
+from typing import (
+    Dict,
+    Iterable,
+    Iterator,
+    MutableMapping,
+    Tuple,
+)
+
 import nox
 from git import tags
 from links import check as _check
 from links import documentation as _documentation
 from links import urls as _urls
-from pyodbc import connect
+from nox import Session
+from nox.sessions import SessionRunner
+from pyodbc import (
+    Connection,
+    connect,
+)
 from version_check import (
     version_from_poetry,
     version_from_python_module,
@@ -54,15 +67,15 @@ class Settings:
 )
 
 
-def find_session_runner(session: nox.Session, name: str):
+def find_session_runner(session: Session, name: str) -> SessionRunner:
     """Helper function to find parameterized action by name"""
     for s, _ in session._runner.manifest.list_all_sessions():
         if name in s.signatures:
             return s
     session.error(f"Could not find a nox session by the name {name!r}")
 
 
-def transaction(connection, sql_statements):
+def transaction(connection: Connection, sql_statements: Iterable[str]) -> None:
     cur = connection.cursor()
     for statement in sql_statements:
         cur.execute(statement)
@@ -71,7 +84,7 @@ def transaction(connection, sql_statements):
 
 
 @contextmanager
-def environment(env_vars):
+def environment(env_vars: Dict[str, str]) -> Iterator[MutableMapping[str, str]]:
     _env = os.environ.copy()
     os.environ.update(env_vars)
     yield os.environ
@@ -80,10 +93,9 @@ def environment(env_vars):
 
 
 @contextmanager
-def temporary_odbc_config(config):
+def temporary_odbc_config(config: str) -> Iterator[Path]:
     with TemporaryDirectory() as tmp_dir:
-        tmp_dir = Path(tmp_dir)
-        config_dir = tmp_dir / "odbcconfig"
+        config_dir = Path(tmp_dir) / "odbcconfig"
         config_dir.mkdir(exist_ok=True)
         config_file = config_dir / "odbcinst.ini"
         with open(config_file, "w") as f:
@@ -92,7 +104,7 @@ def temporary_odbc_config(config):
 
 
 @contextmanager
-def odbcconfig():
+def odbcconfig() -> Iterator[Tuple[Path, MutableMapping[str, str]]]:
     with temporary_odbc_config(
         ODBCINST_INI_TEMPLATE.format(driver=Settings.ODBC_DRIVER)
     ) as cfg:
@@ -102,7 +114,7 @@ def odbcconfig():
 
 
 @nox.session(python=False)
-def fix(session):
+def fix(session: Session) -> None:
     session.run(
         "poetry",
         "run",
@@ -116,7 +128,7 @@ def fix(session):
 
 
 @nox.session(name="code-format", python=False)
-def code_format(session):
+def code_format(session: Session) -> None:
     session.run(
         "poetry",
         "run",
@@ -131,14 +143,14 @@ def code_format(session):
 
 
 @nox.session(python=False)
-def isort(session):
+def isort(session: Session) -> None:
     session.run(
         "poetry", "run", "python", "-m", "isort", "-v", "--check", f"{PROJECT_ROOT}"
     )
 
 
 @nox.session(python=False)
-def lint(session):
+def lint(session: Session) -> None:
     session.run(
         "poetry",
         "run",
@@ -150,13 +162,28 @@ def lint(session):
     )
 
 
+@nox.session(name="type-check", python=False)
+def type_check(session: Session) -> None:
+    session.run(
+        "poetry",
+        "run",
+        "mypy",
+        "--strict",
+        "--show-error-codes",
+        "--pretty",
+        "--show-column-numbers",
+        "--show-error-context",
+        "--scripts-are-modules",
+    )
+
+
 @nox.session(python=False)
 @nox.parametrize("db_version", Settings.DB_VERSIONS)
 @nox.parametrize("connector", Settings.CONNECTORS)
-def verify(session, connector, db_version):
+def verify(session: Session, connector: str, db_version: str) -> None:
     """Prepare and run all available tests"""
 
-    def is_version_in_sync():
+    def is_version_in_sync() -> bool:
         return (
             version_from_python_module(Settings.VERSION_FILE) == version_from_poetry()
         )
@@ -169,7 +196,9 @@ def is_version_in_sync():
         )
     session.notify("isort")
     session.notify("code-format")
+    session.notify("type-check")
     session.notify("lint")
+    session.notify("type-check")
     session.notify(find_session_runner(session, f"db-start(db_version='{db_version}')"))
     session.notify(
         find_session_runner(session, f"integration(connector='{connector}')")
@@ -179,10 +208,10 @@ def is_version_in_sync():
 
 @nox.session(name="db-start", python=False)
 @nox.parametrize("db_version", Settings.DB_VERSIONS)
-def start_db(session, db_version=Settings.DB_VERSIONS[0]):
+def start_db(session: Session, db_version: str = Settings.DB_VERSIONS[0]) -> None:
     """Start the test database"""
 
-    def start():
+    def start() -> None:
         # Consider adding ITDE as dev dependency once ITDE is packaged properly
         with session.chdir(Settings.ITDE):
             session.run(
@@ -202,7 +231,7 @@ def start():
                 external=True,
             )
 
-    def populate():
+    def populate() -> None:
         with odbcconfig():
             settings = {
                 "driver": "EXAODBC",
@@ -236,15 +265,15 @@ def populate():
 
 
 @nox.session(name="db-stop", python=False)
-def stop_db(session):
+def stop_db(session: Session) -> None:
     """Stop the test database"""
     session.run("docker", "kill", "db_container_test", external=True)
     session.run("docker", "kill", "test_container_test", external=True)
 
 
 @nox.session(python=False)
 @nox.parametrize("connector", Settings.CONNECTORS)
-def integration(session, connector):
+def integration(session: Session, connector: str) -> None:
     """Run(s) the integration tests for a specific connector. Expects a test database to be available."""
 
     with odbcconfig() as (config, env):
@@ -259,7 +288,7 @@ def integration(session, connector):
 
 
 @nox.session(name="report-skipped", python=False)
-def report_skipped(session):
+def report_skipped(session: Session) -> None:
     """
     Runs all tests for all supported connectors and creates a csv report of skipped tests for each connector.
 
@@ -301,7 +330,7 @@ def report_skipped(session):
 
 
 @nox.session(name="check-links", python=False)
-def check_links(session):
+def check_links(session: Session) -> None:
     """Checks weather or not all links in the documentation can be accessed"""
     errors = []
     for path, url in _urls(_documentation(PROJECT_ROOT)):
@@ -317,15 +346,15 @@ def check_links(session):
 
 
 @nox.session(name="list-links", python=False)
-def list_links(session):
+def list_links(session: Session) -> None:
     """List all links within the documentation"""
     for path, url in _urls(_documentation(PROJECT_ROOT)):
         session.log(f"Url: {url}, File: {path}")
 
 
 @nox.session(python=False)
-def release(session: nox.Session):
-    def create_parser():
+def release(session: Session) -> None:
+    def create_parser() -> ArgumentParser:
         p = ArgumentParser(
             "Release a pypi package",
             usage="nox -s release -- [-h] [-d]",
@@ -341,7 +370,7 @@ def create_parser():
 
     version_file = version_from_python_module(Settings.VERSION_FILE)
     module_version = version_from_poetry()
-    git_version = version_from_string(tags()[-1])
+    git_version = version_from_string(list(tags())[-1])
 
     if not (module_version == git_version == version_file):
         session.error(

pyproject.toml

@@ -6,7 +6,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "sqlalchemy_exasol"
-version = "3.1.6"
+version = "3.1.7"
 description = "EXASOL dialect for SQLAlchemy"
 readme = "README.rst"
 authors = [
@@ -74,6 +74,7 @@ wheel = "^0.37.1"
 black = "^22.6.0"
 isort = "^5.10.1"
 pylint = "^2.14.5"
+mypy = "^0.971"
 
 [tool.poetry.extras]
 turbodbc = ["turbodbc"]
@@ -104,4 +105,14 @@ fail-under = 5.6
 
 [tool.pylint.format]
 max-line-length = 88
-max-module-lines = 800
+max-module-lines = 800
+
+[tool.mypy]
+files = [
+    'noxfile.py',
+    'scripts/**/*.py',
+    # Incrementaly add files and paths to fix until the entire project is checked
+]
+mypy_path = [
+    'typeshed'
+]

scripts/git.py

@@ -1,10 +1,8 @@
-from subprocess import (
-    PIPE,
-    run,
-)
+from subprocess import run
+from typing import Iterable
 
 
-def tags():
+def tags() -> Iterable[str]:
     """
     Returns a list of all tags, sorted from [0] oldest to [-1] newest.
     PreConditions:
@@ -14,5 +12,4 @@ def tags():
     """
     command = ["git", "tag", "--sort=committerdate"]
     result = run(command, capture_output=True, check=True)
-    tags = (tag.strip() for tag in result.stdout.decode("utf-8").splitlines())
-    return list(tags)
+    return [tag.strip() for tag in result.stdout.decode("utf-8").splitlines()]

scripts/links.py

@@ -3,7 +3,9 @@
 from itertools import repeat
 from pathlib import Path
 from typing import (
+    Container,
     Iterable,
+    Optional,
     Tuple,
 )
 from urllib import request
@@ -13,7 +15,7 @@ def documentation(root: Path) -> Iterable[Path]:
     """Returns an iterator over all documentation files of the project"""
     docs = Path(root).glob("**/*.rst")
 
-    def _deny_filter(path):
+    def _deny_filter(path: Path) -> bool:
         return not ("venv" in path.parts)
 
     return filter(lambda path: _deny_filter(path), docs)
@@ -22,8 +24,8 @@ def _deny_filter(path):
 def urls(files: Iterable[Path]) -> Iterable[Tuple[Path, str]]:
     """Returns an iterable over all urls contained in the provided files"""
 
-    def should_filter(url):
-        _filtered = []
+    def should_filter(url: str) -> bool:
+        _filtered: Container[str] = []
         return url.startswith("mailto") or url in _filtered
 
     for file in files:
@@ -38,12 +40,12 @@ def should_filter(url):
         yield from zip(repeat(file), filter(lambda url: not should_filter(url), _urls))
 
 
-def check(url: str) -> Tuple[int, str]:
+def check(url: str) -> Tuple[Optional[int], str]:
     """Checks if an url is still working (can be accessed)"""
     try:
         # User-Agent needs to be faked otherwise some webpages will deny access with a 403
         req = urllib.request.Request(url, headers={"User-Agent": "Mozilla/5.0"})
         result = request.urlopen(req)
         return result.code, f"{result.msg}"
     except urllib.error.HTTPError as ex:
-        return ex.status, f"{ex}"
+        return ex.code, f"{ex}"