python3.7 support (#437)

* python3.7 support

* do not test with python nightly

* add python nightly (now 3.7-dev) testing

* add forgotten @asyncio.coroutine decorator

* tambourine dances trying to prevent lower tests coverage

* python3.7: __aiter__ MUST return object that implement __anext__

* use psycopg2.connect `async_` kwarg

* Await result before first async iteration in 3.5.2+ in SQL alchemy execute.

Supplements pull request #437 for #436.

* Fix for RuntimeError in Python 3.7+ from unexpected StopIteration raise.

The behavior of iteration has changed to where a StopIteration exception
should not be raised inside a generator except by something unexpected.

* Allow QA of StopAsyncIteration lines, give flake8 built-in hint in <3.5

Resolves Python 3.4 flake8 continuous integration failure.

* bare StopAsyncIteration breaks code coverage in python 3.4

* Revert "bare StopAsyncIteration breaks code coverage in python 3.4"

This reverts commit 8d82522.

* Add proper job for 3.7

* Add 3.7 job w/o debug

Author: smagafurov

.travis.yml

@@ -9,8 +9,22 @@ python:
 - "3.4"
 - "3.5"
 - "3.6"
+- "nightly"
+
+.mixtures:
+- &py3_7-base
+  python: "3.7"
+  dist: xenial
+  sudo: required
+jobs:
+  include:
+  - <<: *py3_7-base
+
+  - <<: *py3_7-base
+    env:
 
 install:
+- pip install -U setuptools
 - python setup.py install
 - pip install -Ur requirements.txt
 - pip install codecov

Makefile

@@ -8,7 +8,7 @@ pep:
 	pep8 aiopg examples tests
 
 flake:
-	extra=$$(python -c "import sys;sys.stdout.write('--exclude tests/pep492') if sys.version_info[:3] < (3, 5, 0) else sys.stdout.write('examples')"); \
+	extra=$$(python -c "import sys;sys.stdout.write('--exclude tests/pep492 --builtins=StopAsyncIteration') if sys.version_info[:3] < (3, 5, 0) else sys.stdout.write('examples')"); \
 	flake8 aiopg tests $$extra
 
 test: flake

aiopg/connection.py

@@ -106,7 +106,7 @@ class Connection:
 
     def __init__(self, dsn, loop, timeout, waiter, echo, **kwargs):
         self._loop = loop
-        self._conn = psycopg2.connect(dsn, async=True, **kwargs)
+        self._conn = psycopg2.connect(dsn, async_=True, **kwargs)
         self._dsn = self._conn.dsn
         assert self._conn.isexecuting(), "Is conn an async at all???"
         self._fileno = self._conn.fileno()

aiopg/cursor.py

@@ -384,7 +384,7 @@ def __iter__(self):
         while True:
             row = yield from self.fetchone()
             if row is None:
-                raise StopIteration
+                return
             else:
                 yield row
 
@@ -402,7 +402,7 @@ def __anext__(self):
             if ret is not None:
                 return ret
             else:
-                raise StopAsyncIteration  # noqa
+                raise StopAsyncIteration
 
         @asyncio.coroutine
         def __aenter__(self):

aiopg/sa/result.py

@@ -335,7 +335,7 @@ def __iter__(self):
         while True:
             row = yield from self.fetchone()
             if row is None:
-                raise StopIteration
+                return
             else:
                 yield row
 
@@ -353,7 +353,7 @@ def __anext__(self):
             if ret is not None:
                 return ret
             else:
-                raise StopAsyncIteration  # noqa
+                raise StopAsyncIteration
 
     def _non_result(self):
         if self._metadata is None:

aiopg/utils.py

@@ -15,7 +15,7 @@
 try:
     ensure_future = asyncio.ensure_future
 except AttributeError:
-    ensure_future = asyncio.async
+    ensure_future = getattr(asyncio, 'async')
 
 
 def create_future(loop):
@@ -86,7 +86,20 @@ class _SAConnectionContextManager(_ContextManager):
     if PY_35:  # pragma: no branch
         if PY_352:
             def __aiter__(self):
-                return self._coro
+                return self
+
+            @asyncio.coroutine
+            def __anext__(self):
+                if self._obj is None:
+                    self._obj = yield from self._coro
+
+                try:
+                    return (yield from self._obj.__anext__())
+                except StopAsyncIteration:
+                    self._obj.close()
+                    self._obj = None
+                    raise
+
         else:
             @asyncio.coroutine
             def __aiter__(self):

tests/test_pool.py

@@ -343,6 +343,7 @@ def test_true_parallel_tasks(create_pool, loop):
     maxsize = 0
     minfreesize = 100
 
+    @asyncio.coroutine
     def inner():
         nonlocal maxsize, minfreesize
         maxsize = max(maxsize, pool.size)