Allow empty fencing_topology (bsc#1025393)

crmsh/parse.py

@@ -1070,7 +1070,7 @@ class FencingOrderParser(BaseParser):
 
     """
     def parse(self, cmd):
-        self.begin(cmd, min_args=1)
+        self.begin(cmd)
         if not self.try_match("fencing-topology"):
             self.match("fencing_topology")
         target = "@@"
@@ -1085,15 +1085,17 @@ def parse(self, cmd):
                 target = self.matched(1)
             else:
                 raw_levels.append((target, self.match_any()))
-        if len(raw_levels) == 0:
-            self.err("Missing list of devices")
         return self._postprocess_levels(raw_levels)
 
     def _postprocess_levels(self, raw_levels):
         from collections import defaultdict
         from itertools import repeat
         from .cibconfig import cib_factory
-        if raw_levels[0][0] == "@@":
+        if len(raw_levels) == 0:
+            def no_levels():
+                return []
+            lvl_generator = no_levels
+        elif raw_levels[0][0] == "@@":
             def node_levels():
                 for node in cib_factory.node_id_list():
                     for target, devices in raw_levels:

test/unittests/test_parse.py

@@ -434,6 +434,10 @@ def test_empty_property_sets(self):
     def test_fencing(self):
         # num test nodes are 3
 
+        out = self._parse('fencing_topology')
+        expect = '<fencing-topology/>'
+        self.assertEqual(expect, etree.tostring(out))
+
         out = self._parse('fencing_topology poison-pill power')
         expect = '<fencing-topology><fencing-level devices="poison-pill" index="1" target="ha-one"/><fencing-level devices="power" index="2" target="ha-one"/><fencing-level devices="poison-pill" index="1" target="ha-three"/><fencing-level devices="power" index="2" target="ha-three"/><fencing-level devices="poison-pill" index="1" target="ha-two"/><fencing-level devices="power" index="2" target="ha-two"/></fencing-topology>'
         self.assertEqual(expect, etree.tostring(out))