Merge pull request #3330 from zsinskri/bpd-sporadic-failure

fix "Sporadic test failures in BPD tests #3309"

Author: sampsyo

Diff for: docs/changelog.rst

@@ -80,6 +80,9 @@ For plugin developers:
   value.
   Thanks to :user:`zsinskri`.
   :bug:`3329`
+* There were sporadic failures in ``test.test_player``. Hopefully these are
+  fixed. If they resurface, please reopen the relevant issue.
+  :bug:`3309` :bug:`3330`
 
 For packagers:
 

Diff for: test/test_player.py

@@ -29,9 +29,8 @@
 import yaml
 import tempfile
 from contextlib import contextmanager
-import random
 
-from beets.util import py3_path
+from beets.util import py3_path, bluelet
 from beetsplug import bpd
 import confuse
 
@@ -231,11 +230,6 @@ def readline(self, terminator=b'\n', bufsize=1024):
                 return line
 
 
-def start_beets(*args):
-    import beets.ui
-    beets.ui.main(list(args))
-
-
 def implements(commands, expectedFailure=False):  # noqa: N803
     def _test(self):
         with self.run_bpd() as client:
@@ -246,6 +240,27 @@ def _test(self):
     return unittest.expectedFailure(_test) if expectedFailure else _test
 
 
+bluelet_listener = bluelet.Listener
+@mock.patch("beets.util.bluelet.Listener")
+def start_server(args, assigned_port, listener_patch):
+    """Start the bpd server, writing the port to `assigned_port`.
+    """
+    def listener_wrap(host, port):
+        """Wrap `bluelet.Listener`, writing the port to `assigend_port`.
+        """
+        # `bluelet.Listener` has previously been saved to
+        # `bluelet_listener` as this function will replace it at its
+        # original location.
+        listener = bluelet_listener(host, port)
+        # read port assigned by OS
+        assigned_port.put_nowait(listener.sock.getsockname()[1])
+        return listener
+    listener_patch.side_effect = listener_wrap
+
+    import beets.ui
+    beets.ui.main(args)
+
+
 class BPDTestHelper(unittest.TestCase, TestHelper):
     def setUp(self):
         self.setup_beets(disk=True)
@@ -263,22 +278,18 @@ def tearDown(self):
         self.unload_plugins()
 
     @contextmanager
-    def run_bpd(self, host='localhost', port=None, password=None,
-                do_hello=True, second_client=False):
+    def run_bpd(self, host='localhost', password=None, do_hello=True,
+                second_client=False):
         """ Runs BPD in another process, configured with the same library
         database as we created in the setUp method. Exposes a client that is
         connected to the server, and kills the server at the end.
         """
-        # Choose a port (randomly) to avoid conflicts between parallel
-        # tests.
-        if not port:
-            port = 9876 + random.randint(0, 10000)
-
         # Create a config file:
         config = {
                 'pluginpath': [py3_path(self.temp_dir)],
                 'plugins': 'bpd',
-                'bpd': {'host': host, 'port': port, 'control_port': port + 1},
+                # use port 0 to let the OS choose a free port
+                'bpd': {'host': host, 'port': 0, 'control_port': 0},
         }
         if password:
             config['bpd']['password'] = password
@@ -290,38 +301,39 @@ def run_bpd(self, host='localhost', port=None, password=None,
         config_file.close()
 
         # Fork and launch BPD in the new process:
-        args = (
+        assigned_port = mp.Queue(2)  # 2 slots, `control_port` and `port`
+        server = mp.Process(target=start_server, args=([
             '--library', self.config['library'].as_filename(),
             '--directory', py3_path(self.libdir),
             '--config', py3_path(config_file.name),
             'bpd'
-        )
-        server = mp.Process(target=start_beets, args=args)
+        ], assigned_port))
         server.start()
 
-        # Wait until the socket is connected:
-        sock, sock2 = None, None
-        for _ in range(20):
+        try:
+            assigned_port.get(timeout=1)  # skip control_port
+            port = assigned_port.get(timeout=0.5)  # read port
+
             sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-            if sock.connect_ex((host, port)) == 0:
-                break
-            else:
-                sock.close()
-                time.sleep(0.01)
-        else:
-            raise RuntimeError('Timed out waiting for the BPD server')
+            try:
+                sock.connect((host, port))
+
+                if second_client:
+                    sock2 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+                    try:
+                        sock2.connect((host, port))
+                        yield (
+                            MPCClient(sock, do_hello),
+                            MPCClient(sock2, do_hello),
+                        )
+                    finally:
+                        sock2.close()
 
-        try:
-            if second_client:
-                sock2 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-                sock2.connect((host, port))
-                yield MPCClient(sock, do_hello), MPCClient(sock2, do_hello)
-            else:
-                yield MPCClient(sock, do_hello)
+                else:
+                    yield MPCClient(sock, do_hello)
+            finally:
+                sock.close()
         finally:
-            sock.close()
-            if sock2:
-                sock2.close()
             server.terminate()
             server.join(timeout=0.2)