Enable mypy strict checks

mypy.ini

@@ -1,3 +1,8 @@
 [mypy]
 ignore_missing_imports = True
-strict_optional = True
+# strict checks
+strict_optional = True
+disallow_any_generics = True
+disallow_untyped_defs = True
+warn_unused_ignores = True
+strict_equality = True

pytest_mypy/collect.py

@@ -1,13 +1,19 @@
 import tempfile
-from typing import Any, Dict, List
+from typing import Any, Dict, List, Iterator, TYPE_CHECKING, Optional
 
 import pytest
 import yaml
 from _pytest.config.argparsing import Parser
+from _pytest.nodes import Node
+from py._path.local import LocalPath
 
 from pytest_mypy import utils
 from pytest_mypy.utils import string_to_bool
 
+if TYPE_CHECKING:
+    from pytest_mypy.item import YamlTestItem
+
+
 
 class File:
     def __init__(self, path: str, content: str):
@@ -36,7 +42,7 @@ def parse_environment_variables(env_vars: List[str]) -> Dict[str, str]:
 
 
 class SafeLineLoader(yaml.SafeLoader):
-    def construct_mapping(self, node, deep=False):
+    def construct_mapping(self, node: yaml.Node, deep: bool = False) -> None:
         mapping = super().construct_mapping(node, deep=deep)
         # Add 1 so line numbering starts at 1
         starting_line = node.start_mark.line + 1
@@ -48,7 +54,7 @@ def construct_mapping(self, node, deep=False):
 
 
 class YamlTestFile(pytest.File):
-    def collect(self):
+    def collect(self) -> Iterator['YamlTestItem']:
         from pytest_mypy.item import YamlTestItem
 
         parsed_file = yaml.load(stream=self.fspath.read_text('utf8'), Loader=SafeLineLoader)
@@ -93,9 +99,10 @@ def collect(self):
                                    mypy_config=additional_mypy_config)
 
 
-def pytest_collect_file(path, parent):
+def pytest_collect_file(path: LocalPath, parent: Node) -> Optional[YamlTestFile]:
     if path.ext in {'.yaml', '.yml'} and path.basename.startswith(('test-', 'test_')):
         return YamlTestFile(path, parent=parent, config=parent.config)
+    return None
 
 
 def pytest_addoption(parser: Parser) -> None:

pytest_mypy/item.py

@@ -14,6 +14,8 @@
 from mypy import build
 from mypy.fscache import FileSystemCache
 from mypy.main import process_options
+from py._io.terminalwriter import TerminalWriter
+
 from pytest_mypy import utils
 from pytest_mypy.collect import File, YamlTestFile
 from pytest_mypy.utils import (
@@ -25,7 +27,7 @@
 
 
 class TraceLastReprEntry(ReprEntry):
-    def toterminal(self, tw):
+    def toterminal(self, tw: TerminalWriter) -> None:
         self.reprfileloc.toterminal(tw)
         for line in self.lines:
             red = line.startswith("E   ")
@@ -199,7 +201,7 @@ def execute_extension_hook(self) -> None:
         extension_hook = getattr(module, func_name)
         extension_hook(self)
 
-    def runtest(self):
+    def runtest(self) -> None:
         try:
             temp_dir = tempfile.TemporaryDirectory(prefix='pytest-mypy-', dir=self.root_directory)
 
@@ -309,5 +311,5 @@ def repr_failure(self, excinfo: ExceptionInfo) -> str:
         else:
             return super().repr_failure(excinfo, style='native')
 
-    def reportinfo(self):
+    def reportinfo(self) -> Tuple[str, Optional[str], str]:
         return self.fspath, None, self.name

pytest_mypy/utils.py

@@ -7,13 +7,13 @@
 import re
 import sys
 from pathlib import Path
-from typing import Callable, Iterator, List, Optional, Tuple
+from typing import Callable, Iterator, List, Optional, Tuple, Union
 
 from decorator import contextmanager
 
 
 @contextmanager
-def temp_environ():
+def temp_environ() -> Iterator[None]:
     """Allow the ability to set os.environ temporarily"""
     environ = dict(os.environ)
     try:
@@ -24,7 +24,7 @@ def temp_environ():
 
 
 @contextmanager
-def temp_path():
+def temp_path() -> Iterator[None]:
     """A context manager which allows the ability to set sys.path temporarily"""
     path = sys.path[:]
     try:
@@ -34,7 +34,7 @@ def temp_path():
 
 
 @contextmanager
-def temp_sys_modules():
+def temp_sys_modules() -> Iterator[None]:
     sys_modules = sys.modules.copy()
     try:
         yield
@@ -56,14 +56,14 @@ def fname_to_module(fpath: Path, root_path: Path) -> Optional[str]:
 
 
 class TypecheckAssertionError(AssertionError):
-    def __init__(self, error_message: Optional[str] = None, lineno: int = 0):
-        self.error_message = error_message
+    def __init__(self, error_message: Optional[str] = None, lineno: int = 0) -> None:
+        self.error_message = error_message or ''
         self.lineno = lineno
 
-    def first_line(self):
+    def first_line(self) -> str:
         return self.__class__.__name__ + '(message="Invalid output")'
 
-    def __str__(self):
+    def __str__(self) -> str:
         return self.error_message
 
 
@@ -258,7 +258,8 @@ def assert_string_arrays_equal(expected: List[str], actual: List[str]) -> None:
                                           lineno=lineno)
 
 
-def build_output_line(fname: str, lnum: int, severity: str, message: str, col=None) -> str:
+def build_output_line(fname: str, lnum: int, severity: str, message: str,
+                      col: Optional[str] = None) -> str:
     if col is None:
         return f'{fname}:{lnum + 1}: {severity}: {message}'
     else:
@@ -294,7 +295,7 @@ def extract_errors_from_comments(fname: str, input_lines: List[str]) -> List[str
 
 
 def get_func_first_lnum(attr: Callable[..., None]) -> Optional[Tuple[int, List[str]]]:
-    lines, _ = inspect.getsourcelines(attr)  # type: ignore[arg-type]
+    lines, _ = inspect.getsourcelines(attr)
     for lnum, line in enumerate(lines):
         no_space_line = line.strip()
         if f'def {attr.__name__}' in no_space_line:
@@ -303,7 +304,7 @@ def get_func_first_lnum(attr: Callable[..., None]) -> Optional[Tuple[int, List[s
 
 
 @contextmanager
-def cd(path):
+def cd(path: Union[str, Path]) -> Iterator[None]:
     """Context manager to temporarily change working directories"""
     if not path:
         return