Remove ProcessPoolExecutor support

Remove the `event_loop_process_pool` fixture and the
`pytest.mark.asyncio_process_pool` marker to address deprecation and
removal detailed in https://bugs.python.org/issue34075.

Fixes pytest-dev#87.

Author: jonafato

README.rst

@@ -88,12 +88,6 @@ If the ``pytest.mark.asyncio`` marker is applied, a pytest hook will
 ensure the produced loop is set as the default global loop.
 Fixtures depending on the ``event_loop`` fixture can expect the policy to be properly modified when they run.
 
-``event_loop_process_pool``
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The ``event_loop_process_pool`` fixture is almost identical to the
-``event_loop`` fixture, except the created event loop will have a
-``concurrent.futures.ProcessPoolExecutor`` set as the default executor.
-
 ``unused_tcp_port``
 ~~~~~~~~~~~~~~~~~~~
 Finds and yields a single unused TCP port on the localhost interface. Useful for
@@ -176,17 +170,15 @@ Only test coroutines will be affected (by default, coroutines prefixed by
 .. |pytestmark| replace:: ``pytestmark``
 .. _pytestmark: http://doc.pytest.org/en/latest/example/markers.html#marking-whole-classes-or-modules
 
-``pytest.mark.asyncio_process_pool``
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The ``asyncio_process_pool`` marker is almost identical to the ``asyncio``
-marker, except the event loop used will have a
-``concurrent.futures.ProcessPoolExecutor`` set as the default executor.
-
 Changelog
 ---------
 
 0.9.0 (UNRELEASED)
 ~~~~~~~~~~~~~~~~~~
+- Python 3.7 support
+- Remove ``event_loop_process_pool`` fixture and
+  ``pytest.mark.asyncio_process_pool`` marker (see
+  https://bugs.python.org/issue34075 for deprecation and removal details)
 
 0.8.0 (2017-09-23)
 ~~~~~~~~~~~~~~~~~~

pytest_asyncio/plugin.py

@@ -3,7 +3,6 @@
 import contextlib
 import inspect
 import socket
-from concurrent.futures import ProcessPoolExecutor
 
 import pytest
 from _pytest.python import transfer_markers
@@ -25,11 +24,6 @@ def pytest_configure(config):
                             "asyncio: "
                             "mark the test as a coroutine, it will be "
                             "run using an asyncio event loop")
-    config.addinivalue_line("markers",
-                            "asyncio_process_pool: "
-                            "mark the test as a coroutine, it will be "
-                            "run using an asyncio event loop with a process "
-                            "pool")
 
 
 @pytest.mark.tryfirst
@@ -44,8 +38,7 @@ def pytest_pycollect_makeitem(collector, name, obj):
         transfer_markers(obj, item.cls, item.module)
         item = pytest.Function(name, parent=collector)  # To reload keywords.
 
-        if ('asyncio' in item.keywords or
-            'asyncio_process_pool' in item.keywords):
+        if 'asyncio' in item.keywords:
             return list(collector._genfunctions(name, obj))
 
 
@@ -170,7 +163,6 @@ def pytest_runtest_setup(item):
 # to marked test functions
 _markers_2_fixtures = {
     'asyncio': 'event_loop',
-    'asyncio_process_pool': 'event_loop_process_pool',
 }
 
 
@@ -182,15 +174,6 @@ def event_loop(request):
     loop.close()
 
 
-@pytest.fixture
-def event_loop_process_pool(event_loop):
-    """Create a fresh instance of the default event loop.
-
-    The event loop will have a process pool set as the default executor."""
-    event_loop.set_default_executor(ProcessPoolExecutor())
-    return event_loop
-
-
 @pytest.fixture
 def unused_tcp_port():
     """Find an unused localhost TCP port from 1024-65535 and return it."""

tests/test_simple.py

@@ -19,20 +19,6 @@ def test_event_loop_fixture(event_loop):
     assert ret == 'ok'
 
 
-def test_event_loop_processpool_fixture(event_loop_process_pool):
-    """Test the injection of the event_loop with a process pool fixture."""
-    assert event_loop_process_pool
-
-    ret = event_loop_process_pool.run_until_complete(
-        async_coro(event_loop_process_pool))
-    assert ret == 'ok'
-
-    this_pid = os.getpid()
-    future = event_loop_process_pool.run_in_executor(None, os.getpid)
-    pool_pid = event_loop_process_pool.run_until_complete(future)
-    assert this_pid != pool_pid
-
-
 @pytest.mark.asyncio
 def test_asyncio_marker():
     """Test the asyncio pytest marker."""
@@ -51,13 +37,6 @@ def test_asyncio_marker_with_default_param(a_param=None):
     yield  # sleep(0)
 
 
-@pytest.mark.asyncio_process_pool
-async def test_asyncio_process_pool_marker(event_loop):
-    """Test the asyncio pytest marker."""
-    ret = await async_coro(event_loop)
-    assert ret == 'ok'
-
-
 @pytest.mark.asyncio
 async def test_unused_port_fixture(unused_tcp_port, event_loop):
     """Test the unused TCP port fixture."""

tests/test_simple_35.py

@@ -20,12 +20,6 @@ async def test_asyncio_marker_with_default_param(a_param=None):
     """Test the asyncio pytest marker."""
 
 
-@pytest.mark.asyncio_process_pool
-async def test_asyncio_process_pool_marker(event_loop):
-    ret = await async_coro(event_loop)
-    assert ret == 'ok'
-
-
 @pytest.mark.asyncio
 async def test_unused_port_fixture(unused_tcp_port, event_loop):
     """Test the unused TCP port fixture."""