Add test code

providers/sftp/src/airflow/providers/sftp/hooks/sftp.py

@@ -148,6 +148,10 @@ def get_managed_conn(self) -> Generator[SFTPClient, None, None]:
                 self._ssh_conn.close()
                 self._ssh_conn = None
 
+    def get_conn_count(self) -> int:
+        """Get the number of open connections."""
+        return self._conn_count
+
     def describe_directory(self, path: str) -> dict[str, dict[str, str | int | None]]:
         """
         Get file information in a directory on the remote system.

providers/sftp/tests/unit/sftp/hooks/test_sftp.py

@@ -114,8 +114,14 @@ def test_close_conn(self):
         assert self.hook.conn is None
 
     def test_get_managed_conn(self):
-        with self.hook.get_managed_conn() as conn:
-            assert isinstance(conn, paramiko.SFTPClient)
+        with self.hook.get_managed_conn() as conn1:
+            assert isinstance(conn1, paramiko.SFTPClient)
+            with self.hook.get_managed_conn() as conn2:
+                assert conn1 == conn2
+                assert self.hook.get_conn_count() == 2
+            assert self.hook.get_conn_count() == 1
+        assert self.hook.get_conn_count() == 0
+        assert self.hook.conn is None
 
     @patch("airflow.providers.ssh.hooks.ssh.SSHHook.get_conn")
     def test_get_close_conn(self, mock_get_conn):