[cdc_stream] Use ephemeral ports (#100)

Instead of running netstat/ss on local and remote systems, just bind
with port 0 to find an ephemeral port. This is much more robust,
simpler and a bit faster. Since the remote port is only known after
running cdc_fuse_fs, port forwarding has to be set up after running
cdc_fuse_fs.

integration_tests/cdc_stream/general_test.py

@@ -109,12 +109,14 @@ class GeneralTest(test_base.CdcStreamTest):
     self._test_dir_content(files=[], dirs=[])
     self.assertGreater(self._get_cache_size_in_bytes(), cache_size)
 
+  def test_rename_file(self):
     filename = 'file1.txt'
     file_local_path = os.path.join(self.local_base_dir, filename)
     utils.create_test_file(file_local_path, 1024)
     self._start()
     self._test_dir_content(files=[filename], dirs=[])
     cache_size = self._get_cache_size_in_bytes()
+    original = utils.get_ssh_command_output(self.ls_cmd)
 
     # After a file is renamed, the manifest is updated.
     renamed_filename = 'file2.txt'

integration_tests/cdc_stream/test_base.py

@@ -129,17 +129,17 @@ class CdcStreamTest(unittest.TestCase):
                            utils.target(self.remote_base_dir),
                            self.service_port_arg)
     self._assert_stream_success(res)
+    CdcStreamTest.service_running = True
 
   def _stop(self, ignore_not_found=False):
     """Stops streaming to the target
 
     Args:
-        local_dir (string): Directory to stream. Defaults to local_base_dir.
+        ignore_not_found (bool): True to ignore if there's nothing to stop.
     """
-    if not self.service_running:
+    if not CdcStreamTest.service_running:
       return
-    res = utils.run_stream('stop', utils.target(self.remote_base_dir),
-                           self.service_port_arg)
+    res = utils.run_stream('stop', '*', self.service_port_arg)
     if ignore_not_found and res.returncode == self.NOT_FOUND:
       return
     self._assert_stream_success(res)