Test Windows Python 3.x with GitHub Actions

Keep testing 2.7 with AppVeyor as GitHub Actions makes it hard to test
Python 2.7 on Windows and Nox.

.github/workflows/ci.yml

@@ -0,0 +1,31 @@
+name: Continuous integration
+
+on: [push, pull_request]
+
+jobs:
+  build:
+
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: [3.5, 3.6, 3.7, 3.8]
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v1
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python.exe -m pip install --upgrade pip wheel nox
+    - name: Test
+      run: |
+        python.exe -m nox -s test-${{ matrix.python-version }}
+    - name: Coverage upload
+      env:
+        CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+      run: |
+        python.exe -m pip install codecov
+        python.exe -m codecov

appveyor.yml

@@ -12,21 +12,6 @@ environment:
       PYTHON_ARCH: "64"
       NOX_SESSION: "test-2.7"
 
-    - PYTHON: "C:\\Python35-x64"
-      PYTHON_VERSION: "3.5.x"
-      PYTHON_ARCH: "64"
-      NOX_SESSION: "test-3.5"
-
-    - PYTHON: "C:\\Python36-x64"
-      PYTHON_VERSION: "3.6.x"
-      PYTHON_ARCH: "64"
-      NOX_SESSION: "test-3.6"
-
-    - PYTHON: "C:\\Python37-x64"
-      PYTHON_VERSION: "3.7.x"
-      PYTHON_ARCH: "64"
-      NOX_SESSION: "test-3.7"
-
 cache:
   - C:\Users\appveyor\AppData\Local\pip\Cache
 

test/__init__.py

@@ -36,7 +36,7 @@
 # 3. To test our timeout logic by using two different values, eg. by using different
 #    values at the pool level and at the request level.
 SHORT_TIMEOUT = 0.001
-LONG_TIMEOUT = 0.5 if os.environ.get("CI") else 0.01
+LONG_TIMEOUT = 0.5 if os.environ.get("CI") or os.environ.get("GITHUB_ACTIONS") else 0.01
 
 
 def clear_warnings(cls=HTTPWarning):

test/conftest.py

@@ -1,5 +1,16 @@
+import platform
 import sys
 
+import pytest
+
 # We support Python 3.6+ for async code
 if sys.version_info[:2] < (3, 6):
     collect_ignore_glob = ["async/*.py", "with_dummyserver/async/*.py"]
+
+# The Python 3.8+ default loop on Windows breaks Tornado
+@pytest.fixture(scope="session", autouse=True)
+def configure_windows_event_loop():
+    if sys.version_info >= (3, 8) and platform.system() == "Windows":
+        import asyncio
+
+        asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())