Fix state leakage between integration tests

cylc/flow/scheduler.py

@@ -16,19 +16,20 @@
 """Cylc scheduler server."""
 
 import asyncio
+import os
+import sys
+import traceback
 from collections import deque
 from contextlib import suppress
-import os
 from pathlib import Path
 from queue import Empty, Queue
 from shlex import quote
 from socket import gaierror
 from subprocess import DEVNULL, PIPE, Popen
-import sys
 from threading import Barrier, Thread
 from time import sleep, time
-import traceback
 from typing import (
+    TYPE_CHECKING,
     Any,
     AsyncGenerator,
     Callable,
@@ -38,41 +39,30 @@
     NoReturn,
     Optional,
     Set,
-    TYPE_CHECKING,
     Tuple,
     Union,
 )
 from uuid import uuid4
 
 import psutil
 
+import cylc.flow.flags
 from cylc.flow import (
     LOG,
     __version__ as CYLC_VERSION,
+    commands,
     main_loop,
+    workflow_files,
 )
-from cylc.flow import workflow_files
 from cylc.flow.broadcast_mgr import BroadcastMgr
 from cylc.flow.cfgspec.glbl_cfg import glbl_cfg
 from cylc.flow.config import WorkflowConfig
-from cylc.flow import commands
 from cylc.flow.data_store_mgr import DataStoreMgr
-from cylc.flow.exceptions import (
-    CommandFailedError,
-    CylcError,
-    InputError,
-)
-import cylc.flow.flags
+from cylc.flow.exceptions import CommandFailedError, CylcError, InputError
 from cylc.flow.flow_mgr import FLOW_NEW, FLOW_NONE, FlowMgr
-from cylc.flow.host_select import (
-    HostSelectException,
-    select_workflow_host,
-)
-from cylc.flow.hostuserutil import (
-    get_host,
-    get_user,
-    is_remote_platform,
-)
+from cylc.flow.graphnode import GraphNodeParser
+from cylc.flow.host_select import HostSelectException, select_workflow_host
+from cylc.flow.hostuserutil import get_host, get_user, is_remote_platform
 from cylc.flow.id import Tokens
 from cylc.flow.log_level import verbosity_to_env, verbosity_to_opts
 from cylc.flow.loggingutil import (
@@ -86,8 +76,8 @@
 from cylc.flow.network import API
 from cylc.flow.network.authentication import key_housekeeping
 from cylc.flow.network.server import WorkflowRuntimeServer
-from cylc.flow.parsec.OrderedDict import DictTree
 from cylc.flow.parsec.exceptions import ParsecError
+from cylc.flow.parsec.OrderedDict import DictTree
 from cylc.flow.parsec.validate import DurationFloat
 from cylc.flow.pathutil import (
     get_workflow_name_from_id,
@@ -121,16 +111,15 @@
     REMOTE_INIT_FAILED,
 )
 from cylc.flow.task_state import (
-    TASK_STATUSES_ACTIVE,
-    TASK_STATUSES_NEVER_ACTIVE,
     TASK_STATUS_PREPARING,
     TASK_STATUS_RUNNING,
     TASK_STATUS_SUBMITTED,
     TASK_STATUS_WAITING,
+    TASK_STATUSES_ACTIVE,
+    TASK_STATUSES_NEVER_ACTIVE,
 )
 from cylc.flow.taskdef import TaskDef
-from cylc.flow.templatevars import eval_var
-from cylc.flow.templatevars import get_template_vars
+from cylc.flow.templatevars import eval_var, get_template_vars
 from cylc.flow.timer import Timer
 from cylc.flow.util import cli_format
 from cylc.flow.wallclock import (
@@ -143,12 +132,15 @@
 from cylc.flow.workflow_status import AutoRestartMode, RunMode, StopMode
 from cylc.flow.xtrigger_mgr import XtriggerManager
 
+
 if TYPE_CHECKING:
     # BACK COMPAT: typing_extensions.Literal
     # FROM: Python 3.7
     # TO: Python 3.8
-    from typing_extensions import Literal
     from optparse import Values
+
+    from typing_extensions import Literal
+
     from cylc.flow.network.resolvers import TaskMsg
 
 
@@ -408,6 +400,10 @@ async def initialise(self):
 
         self.profiler = Profiler(self, self.options.profile_mode)
 
+        # Reset graph node parser singleton
+        # (mainly to prevent state leakage between integration tests):
+        GraphNodeParser.get_inst().clear()
+
     async def configure(self, params):
         """Configure the scheduler.