Use a random port for WebAgg tests

QuLogic · QuLogic · commit 91089d9410e7 · 2022-10-03T21:11:05.000-04:00
This prevents them from conflicting when run in parallel. Even though
there is some attempt to pick alternative ports, that seems to cause a
socket leak somewhere in Tornado, which Pytest converts to an error, so
we have to do it manually.

Also ensure the interactive WebAgg subprocess is actually killed.
diff --git a/lib/matplotlib/tests/conftest.py b/lib/matplotlib/tests/conftest.py
@@ -1,2 +1,20 @@
+import contextlib
+import socket
+
+import pytest
+
 from matplotlib.testing.conftest import (  # noqa
     mpl_test_settings, pytest_configure, pytest_unconfigure, pd, xr)
+
+
+@pytest.fixture
+def random_port():
+    with contextlib.closing(
+            socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
+        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        s.bind(('', 0))
+        s.listen(1)
+        addr = s.getsockname()
+        port = addr[1]
+
+    return port
diff --git a/lib/matplotlib/tests/test_backend_webagg.py b/lib/matplotlib/tests/test_backend_webagg.py
@@ -52,14 +52,14 @@ def test_webagg_core_no_toolbar():
 
 
 @pytest.mark.backend('webagg')
-def test_webagg_general(page):
+def test_webagg_general(random_port, page):
     from playwright.sync_api import expect
 
     fig, ax = plt.subplots(facecolor='w')
 
     # Don't start the Tornado event loop, but use the existing event loop
     # started by the `page` fixture.
-    WebAggApplication.initialize()
+    WebAggApplication.initialize(port=random_port)
     WebAggApplication.started = True
 
     page.goto(f'http://{WebAggApplication.address}:{WebAggApplication.port}/')
@@ -85,7 +85,7 @@ def test_webagg_general(page):
 
 @pytest.mark.backend('webagg')
 @pytest.mark.parametrize('toolbar', ['toolbar2', 'toolmanager'])
-def test_webagg_toolbar(page, toolbar):
+def test_webagg_toolbar(random_port, page, toolbar):
     from playwright.sync_api import expect
 
     with warnings.catch_warnings():
@@ -97,7 +97,7 @@ def test_webagg_toolbar(page, toolbar):
 
     # Don't start the Tornado event loop, but use the existing event loop
     # started by the `page` fixture.
-    WebAggApplication.initialize()
+    WebAggApplication.initialize(port=random_port)
     WebAggApplication.started = True
 
     page.goto(f'http://{WebAggApplication.address}:{WebAggApplication.port}/')
@@ -143,14 +143,14 @@ def test_webagg_toolbar(page, toolbar):
 
 
 @pytest.mark.backend('webagg')
-def test_webagg_toolbar_save(page):
+def test_webagg_toolbar_save(random_port, page):
     from playwright.sync_api import expect
 
     fig, ax = plt.subplots(facecolor='w')
 
     # Don't start the Tornado event loop, but use the existing event loop
     # started by the `page` fixture.
-    WebAggApplication.initialize()
+    WebAggApplication.initialize(port=random_port)
     WebAggApplication.started = True
 
     page.goto(f'http://{WebAggApplication.address}:{WebAggApplication.port}/')
diff --git a/lib/matplotlib/tests/test_backends_interactive.py b/lib/matplotlib/tests/test_backends_interactive.py
@@ -371,15 +371,15 @@ def test_cross_Qt_imports():
 @pytest.mark.skipif('TF_BUILD' in os.environ,
                     reason="this test fails an azure for unknown reasons")
 @pytest.mark.skipif(os.name == "nt", reason="Cannot send SIGINT on Windows.")
-def test_webagg():
+def test_webagg(random_port):
     pytest.importorskip("tornado")
     proc = subprocess.Popen(
         [sys.executable, "-c",
          inspect.getsource(_test_interactive_impl)
-         + "\n_test_interactive_impl()", "{}"],
+         + "\n_test_interactive_impl()",
+         json.dumps({'webagg.port': random_port})],
         env={**os.environ, "MPLBACKEND": "webagg", "SOURCE_DATE_EPOCH": "0"})
-    url = "http://{}:{}".format(
-        mpl.rcParams["webagg.address"], mpl.rcParams["webagg.port"])
+    url = f'http://{mpl.rcParams["webagg.address"]}:{random_port}'
     timeout = time.perf_counter() + _test_timeout
     while True:
         try:
@@ -395,7 +395,12 @@ def test_webagg():
                 continue
     conn.close()
     proc.send_signal(signal.SIGINT)
-    assert proc.wait(timeout=_test_timeout) == 0
+    try:
+        assert proc.wait(timeout=_test_timeout) == 0
+    except subprocess.TimeoutExpired:
+        proc.kill()
+        proc.wait(timeout=_test_timeout)
+        raise
 
 
 def _lazy_headless():
