refactor: harden mypy rules

pyproject.toml

@@ -149,6 +149,8 @@ ignore = [
 
 [tool.mypy]
 files = ["language_tool_python", "tests"]
+disallow_any_decorated = true
+disallow_any_explicit = true
 disallow_any_expr = true
 disallow_any_generics = true
 disallow_any_unimported = true
@@ -162,6 +164,7 @@ no_implicit_reexport = true
 pretty = true
 show_error_codes = true
 strict_equality = true
+strict_equality_for_none = true
 warn_redundant_casts = true
 warn_return_any = true
 warn_unreachable = true

tests/test_download.py

@@ -572,7 +572,7 @@ def test_install_oldest_supported_version() -> None:
             "en-US",
             language_tool_download_version="4.0",
         ) as tool:
-            assert tool is not None
+            assert tool.language_tool_download_version == "4.0"
     except LanguageToolError:
         pytest.fail("Failed to download or initialize the oldest supported version.")
 
@@ -592,7 +592,9 @@ def test_install_snapshot_version() -> None:
                 (datetime.now(timezone.utc) - timedelta(days=3)).strftime("%Y%m%d")
             ),
         ) as tool:
-            assert tool is not None
+            assert tool.language_tool_download_version == (
+                datetime.now(timezone.utc) - timedelta(days=3)
+            ).strftime("%Y%m%d")
     except LanguageToolError:
         pytest.skip(
             (