fix some more test cases for terminal finder

Author: wxtim

cylc/flow/graph_parser.py

@@ -489,14 +489,19 @@ def get_graph_terminals(pairs):
             {'bar'}
         """
         lefts = []
-        for left, _ in pairs:
+        rights = []
+        for left, right in pairs:
             if left and ('&' in left or '|' in left):
                 # RE used because don't want to have to worry about
                 # mutiple and/or and cleaning whitespace.
                 lefts += GraphParser._RE_ANDOR.split(left)
             else:
                 lefts.append(left)
-        return {p[1] for p in pairs}.difference(set(lefts))
+            if right and ('&' in right or '|' in right):
+                rights += GraphParser._RE_ANDOR.split(right)
+            else:
+                rights.append(right)
+        return set(rights).difference(set(lefts))
 
     @classmethod
     def _report_invalid_lines(cls, lines: List[str]) -> None:

tests/unit/test_graph_parser.py

@@ -1018,6 +1018,20 @@ def test_proc_dep_pair(args, err):
             {'foo'},
             id='&-and-|'
         ),
+        param(
+            {
+                (None, 'stop1'),
+                ('stop1', 't3:start&t4:start'),
+                ('t3:start&t4:start', 'stop2?')
+            },
+            {'stop2?'},
+            id='diamond-graph'
+        ),
+        param(
+            {(None, 'stop1'), ('stop1', 't3:start&t4')},
+            {'t3:start', 't4'},
+            id='y-shape-graph'
+        ),
     )
 )
 def test_get_graph_terminals(pairs, terminals):