Enable mypy (#20)

Author: ssbarnea

.pre-commit-config.yaml

@@ -40,6 +40,14 @@ repos:
     hooks:
       - id: ruff
         args: [--fix, --exit-non-zero-on-fix]
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v1.6.0
+    hooks:
+      - id: mypy
+        # empty args needed in order to match mypy cli behavior
+        args: [--strict]
+        additional_dependencies:
+          - pytest
   - repo: https://github.com/adrienverge/yamllint.git
     rev: v1.32.0
     hooks:

src/pytest_plus/__init__.py

@@ -3,6 +3,7 @@
 import os
 
 import pytest
+from _pytest.terminal import TerminalReporter
 
 
 def pytest_sessionfinish(session: pytest.Session) -> None:
@@ -13,6 +14,8 @@ def pytest_sessionfinish(session: pytest.Session) -> None:
     that functionality is ignored.
     """
     terminalreporter = session.config.pluginmanager.get_plugin("terminalreporter")
+    if not isinstance(terminalreporter, TerminalReporter):
+        raise TypeError
     req_passed = int(os.environ.get("PYTEST_REQPASS", "0"))
     if req_passed and not session.config.option.collectonly:
         passed = 0
@@ -27,7 +30,7 @@ def pytest_sessionfinish(session: pytest.Session) -> None:
             session.exitstatus = 1
 
 
-@pytest.hookimpl(tryfirst=True)
+@pytest.hookimpl(tryfirst=True)  # type: ignore[misc,unused-ignore]
 def pytest_collection_modifyitems(items: list[pytest.Item]) -> None:
     """Ensure testing fails if tests have duplicate names."""
     errors = []