testing: test that RPC calls made in shutdown fail and receive error code -5

and the two conditions in which plugins can receive shutdown notification

tests/plugins/misc_notifications.py

@@ -2,9 +2,10 @@
 """Plugin to be used to test miscellaneous notifications.
 """
 
-from pyln.client import Plugin
+from pyln.client import Plugin, RpcError
 from time import sleep
 import sys
+import pytest
 
 plugin = Plugin()
 
@@ -29,6 +30,23 @@ def channel_state_changed(plugin, channel_state_changed, **kwargs):
 
 @plugin.subscribe("shutdown")
 def shutdown(plugin, **kwargs):
+    plugin.log("received shutdown notification")
+
+    # 'shutdown' notification can be called in two ways, from `plugin stop` or from
+    # lightningd's shutdown loop, we test which one by making `getinfo` call
+    try:
+        plugin.rpc.getinfo()
+        plugin.rpc.datastore(key='test', string='Allowed', mode="create-or-append")
+        plugin.log("datastore success")
+    except RpcError as e:
+        if e.error == {'code': -5, 'message': 'lightningd is shutting down'}:
+            # JSON RPC is disabled by now, but can do logging
+            with pytest.raises(RpcError, match=r'-5.*lightningd is shutting down'):
+                plugin.rpc.datastore(key='test', string='Not allowed', mode="create-or-append")
+            plugin.log("datastore failed")
+        else:
+            raise
+
     plugin.log("delaying shutdown with 5s")
     sleep(5)
     sys.exit(0)

tests/test_plugin.py

@@ -1086,7 +1086,7 @@ def test_htlc_accepted_hook_direct_restart(node_factory, executor):
 
 def test_htlc_accepted_hook_shutdown(node_factory, executor):
     """Hooks of important-plugins are never removed and these plugins are kept
-       alive until after subdaemons are shutdown.
+       alive until after subdaemons are shutdown. Also tests shutdown notification.
     """
     l1, l2 = node_factory.line_graph(2, opts=[
         {'may_reconnect': True, 'log-level': 'info'},
@@ -1095,6 +1095,10 @@ def test_htlc_accepted_hook_shutdown(node_factory, executor):
          'important-plugin': [os.path.join(os.getcwd(), 'tests/plugins/fail_htlcs.py')]}
     ])
 
+    l2.rpc.plugin_stop(os.path.join(os.getcwd(), 'tests/plugins/misc_notifications.py'))
+    l2.daemon.wait_for_log(r'datastore success')
+    l2.rpc.plugin_start(os.path.join(os.getcwd(), 'tests/plugins/misc_notifications.py'))
+
     i1 = l2.rpc.invoice(msatoshi=1000, label="inv1", description="desc")['bolt11']
 
     # fail_htlcs.py makes payment fail
@@ -1107,6 +1111,8 @@ def test_htlc_accepted_hook_shutdown(node_factory, executor):
     # Should still fail htlc while shutting down
     with pytest.raises(RpcError):
         l1.rpc.pay(i1)
+
+    l2.daemon.wait_for_log(r'datastore failed')
     f_stop.result()