Make the proactor helper _private for now

Author: altendky

README.rst

@@ -44,19 +44,31 @@ exception such as below.
     NotImplementedError
 
 The previous default, the selector loop, still works but you have to
-explicitly set it.  ``pytest_twisted.use_asyncio_selector_if_required()``
-is provided to help in choosing the selector loop.  It must be called
-early so the following `conftest.py` is suggested.
+explicitly set it and do so early. The following ``conftest.py`` is provided
+for reference.
 
 .. code-block:: python3
 
+    import sys
+
     import pytest
     import pytest_twisted
 
 
     @pytest.hookimpl(tryfirst=True)
     def pytest_configure(config):
-        pytest_twisted.use_asyncio_selector_if_required(config=config)
+        # https://twistedmatrix.com/trac/ticket/9766
+        # https://github.com/pytest-dev/pytest-twisted/issues/80
+
+        if (
+            config.getoption("reactor", "default") == "asyncio"
+            and sys.platform == 'win32'
+            and sys.version_info >= (3, 8)
+        ):
+            import asyncio
+
+            selector_policy = asyncio.WindowsSelectorEventLoopPolicy()
+            asyncio.set_event_loop_policy(selector_policy)
 
 
 Python 2 support plans

pytest_twisted.py

@@ -329,8 +329,9 @@ def pytest_configure(config):
     reactor_installers[config.getoption("reactor")]()
 
 
-def use_asyncio_selector_if_required(config):
+def _use_asyncio_selector_if_required(config):
     # https://twistedmatrix.com/trac/ticket/9766
+    # https://github.com/pytest-dev/pytest-twisted/issues/80
 
     if (
         config.getoption("reactor", "default") == "asyncio"

testing/conftest.py

@@ -7,4 +7,4 @@
 
 @pytest.hookimpl(tryfirst=True)
 def pytest_configure(config):
-    pytest_twisted.use_asyncio_selector_if_required(config=config)
+    pytest_twisted._use_asyncio_selector_if_required(config=config)

testing/test_basic.py

@@ -58,7 +58,7 @@ def _default_conftest(testdir):
 
     @pytest.hookimpl(tryfirst=True)
     def pytest_configure(config):
-        pytest_twisted.use_asyncio_selector_if_required(config=config)
+        pytest_twisted._use_asyncio_selector_if_required(config=config)
     """))
 
 
@@ -646,7 +646,7 @@ def test_blockon_in_hook_with_asyncio(testdir, cmd_opts, request):
 
     @pytest.hookimpl(tryfirst=True)
     def pytest_configure(config):
-        pt.use_asyncio_selector_if_required(config=config)
+        pt._use_asyncio_selector_if_required(config=config)
 
         pt.init_asyncio_reactor()
         d = defer.Deferred()
@@ -679,7 +679,7 @@ def test_wrong_reactor_with_asyncio(testdir, cmd_opts, request):
     
     @pytest.hookimpl(tryfirst=True)
     def pytest_configure(config):
-        pytest_twisted.use_asyncio_selector_if_required(config=config)
+        pytest_twisted._use_asyncio_selector_if_required(config=config)
 
     def pytest_addhooks():
         import twisted.internet.default