Fix strict mypy errors in plugin and scripts (#363)

This is a precondition for enabling mypy self-check in CI.

* Fixed strict mypy errors in mypy_drf_plugin and scripts
* Harmonized a few things in scripts/typecheck_tests.py with related code in django-stubs

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: intgr

mypy_drf_plugin/main.py

@@ -1,4 +1,4 @@
-from typing import Callable, Dict, Optional
+from typing import Callable, Dict, Optional, Type
 
 from mypy.nodes import TypeInfo
 from mypy.options import Options
@@ -28,9 +28,10 @@ def __init__(self, options: Options) -> None:
     def _get_currently_defined_serializers(self) -> Dict[str, int]:
         base_serializer_sym = self.lookup_fully_qualified(fullnames.BASE_SERIALIZER_FULLNAME)
         if base_serializer_sym is not None and isinstance(base_serializer_sym.node, TypeInfo):
-            return base_serializer_sym.node.metadata.setdefault("drf", {}).setdefault(
+            serializer_bases: Dict[str, int] = base_serializer_sym.node.metadata.setdefault("drf", {}).setdefault(
                 "serializer_bases", {fullnames.BASE_SERIALIZER_FULLNAME: 1}
             )
+            return serializer_bases
         else:
             return {}
 
@@ -40,5 +41,5 @@ def get_base_class_hook(self, fullname: str) -> Optional[Callable[[ClassDefConte
         return None
 
 
-def plugin(version):
+def plugin(version: str) -> Type[NewSemanalDRFPlugin]:
     return NewSemanalDRFPlugin

scripts/git_helpers.py

@@ -1,6 +1,7 @@
-from typing import Optional
+from typing import Optional, Union
 
-from git import RemoteProgress, Repo
+from git.remote import RemoteProgress
+from git.repo import Repo
 
 from scripts.paths import DRF_SOURCE_DIRECTORY
 
@@ -9,7 +10,9 @@ class ProgressPrinter(RemoteProgress):
     def line_dropped(self, line: str) -> None:
         print(line)
 
-    def update(self, op_code, cur_count, max_count=None, message=""):
+    def update(
+        self, op_code: int, cur_count: Union[str, float], max_count: Union[str, float, None] = None, message: str = ""
+    ) -> None:
         print(self._cur_line)
 
 
@@ -19,7 +22,7 @@ def git_checkout_drf(commit_ref: Optional[str] = None) -> None:
         repository = Repo.clone_from(
             "https://github.com/encode/django-rest-framework.git",
             DRF_SOURCE_DIRECTORY,
-            progress=ProgressPrinter(),
+            progress=ProgressPrinter(),  # type: ignore
             branch="master",
             depth=100,
         )

scripts/typecheck_tests.py

@@ -5,7 +5,7 @@
 from argparse import ArgumentParser
 from collections import defaultdict
 from distutils import dir_util, spawn
-from typing import Dict, List, Pattern, Union
+from typing import DefaultDict, List, Pattern, Union
 
 from scripts.git_helpers import git_checkout_drf
 from scripts.paths import DRF_SOURCE_DIRECTORY, PROJECT_DIRECTORY, STUBS_DIRECTORY
@@ -14,8 +14,8 @@
 # This should be updated periodically or after every DRF release.
 DRF_GIT_REF = "22d206c1e0dbc03840c4d190f7eda537c0f2010a"
 
-IGNORED_MODULES = []
-MOCK_OBJECTS = [
+IGNORED_MODULES: List[str] = []
+MOCK_OBJECTS: List[str] = [
     "MockQueryset",
     "MockRequest",
     "TypeErrorQueryset",
@@ -253,8 +253,10 @@
     "utils.py": ['Invalid signature "Callable[[BadType], Any]"'],
 }
 
+_DictToSearch = DefaultDict[str, DefaultDict[Union[str, Pattern[str]], int]]
 
-def get_unused_ignores(ignored_message_freq: Dict[str, Dict[Union[str, Pattern], int]]) -> List[str]:
+
+def get_unused_ignores(ignored_message_freq: _DictToSearch) -> List[str]:
     unused_ignores = []
     for root_key, patterns in IGNORED_ERRORS.items():
         for pattern in patterns:
@@ -265,7 +267,7 @@ def get_unused_ignores(ignored_message_freq: Dict[str, Dict[Union[str, Pattern],
     return unused_ignores
 
 
-def is_pattern_fits(pattern: Union[Pattern, str], line: str):
+def does_pattern_fit(pattern: Union[Pattern[str], str], line: str) -> bool:
     if isinstance(pattern, Pattern):
         if pattern.search(line):
             return True
@@ -275,15 +277,15 @@ def is_pattern_fits(pattern: Union[Pattern, str], line: str):
     return False
 
 
-def is_ignored(line: str, filename: str, ignored_message_dict: Dict[str, Dict[str, int]]) -> bool:
+def is_ignored(line: str, filename: str, *, ignored_message_freqs: _DictToSearch) -> bool:
     if "runtests" in line or filename in IGNORED_MODULES:
         return True
     for pattern in IGNORED_ERRORS["__common__"]:
         if pattern in line:
             return True
     for pattern in IGNORED_ERRORS.get(filename, []):
-        if is_pattern_fits(pattern, line):
-            ignored_message_dict[test_filename][pattern] += 1
+        if does_pattern_fit(pattern, line):
+            ignored_message_freqs[test_filename][pattern] += 1
             return True
     for mock_object in MOCK_OBJECTS:
         if mock_object in line:
@@ -322,13 +324,13 @@ def update(self, op_code, cur_count, max_count=None, message=""):
         mypy_executable = spawn.find_executable("mypy")
         mypy_argv = [mypy_executable, *mypy_options]
         completed = subprocess.run(
-            mypy_argv,
+            mypy_argv,  # type: ignore
             env={"PYTHONPATH": str(PROJECT_DIRECTORY)},
             stdout=subprocess.PIPE,
             stderr=subprocess.STDOUT,
         )
         output = completed.stdout.decode()
-        ignored_message_freqs = defaultdict(lambda: defaultdict(int))
+        ignored_message_freqs: _DictToSearch = defaultdict(lambda: defaultdict(int))
         sorted_lines = sorted(output.splitlines())
         for line in sorted_lines:
             try:
@@ -337,7 +339,7 @@ def update(self, op_code, cur_count, max_count=None, message=""):
             except IndexError:
                 test_filename = "unknown"
 
-            if not is_ignored(line, test_filename, ignored_message_dict=ignored_message_freqs):
+            if not is_ignored(line, test_filename, ignored_message_freqs=ignored_message_freqs):
                 global_rc = 1
                 print(line)