Avoid using _pytest

Even though `MonkeyPatch` will become public in the next pytest release
(as `pytest.MonkeyPatch`), it's better to avoid the `_pytest` namespace.

Author: bluetech

setup.cfg

@@ -21,7 +21,7 @@ combine_as_imports=True
 force_grid_wrap=0
 include_trailing_comma=True
 known_first_party=wsproto, test
-known_third_party=h11, pytest, _pytest
+known_third_party=h11, pytest
 line_length=88
 multi_line_output=3
 no_lines_before=LOCALFOLDER
@@ -51,5 +51,3 @@ warn_unused_ignores = True
 ignore_missing_imports = True
 [mypy-pytest.*]
 ignore_missing_imports = True
-[mypy-_pytest.*]
-ignore_missing_imports = True

test/test_permessage_deflate.py

@@ -2,7 +2,6 @@
 from typing import cast, Optional, Sequence, TYPE_CHECKING
 
 import pytest
-from _pytest.monkeypatch import MonkeyPatch
 
 from wsproto import extensions as wpext, frame_protocol as fp
 
@@ -348,7 +347,7 @@ def test_inbound_bad_zlib_payload(self) -> None:
         result2 = ext.frame_inbound_payload_data(proto, compressed_payload)
         assert result2 is fp.CloseReason.INVALID_FRAME_PAYLOAD_DATA
 
-    def test_inbound_bad_zlib_decoder_end_state(self, monkeypatch: MonkeyPatch) -> None:
+    def test_inbound_bad_zlib_decoder_end_state(self) -> None:
         compressed_payload = b"x" * 23
 
         ext = wpext.PerMessageDeflate()
@@ -371,9 +370,9 @@ def decompress(self, data: bytes) -> bytes:
             def flush(self) -> None:
                 raise zlib.error()
 
-        monkeypatch.setattr(ext, "_decompressor", FailDecompressor())
-
+        ext._decompressor = cast("zlib._Decompress", FailDecompressor())
         result2 = ext.frame_inbound_complete(proto, True)
+
         assert result2 is fp.CloseReason.INVALID_FRAME_PAYLOAD_DATA
 
     @pytest.mark.parametrize(