broadcast: reject truncated cycle points

changes.d/6414.fix.md

@@ -0,0 +1 @@
+Broadcast will now reject truncated cycle points to aviod runtime errors.

cylc/flow/cycling/__init__.py

@@ -91,8 +91,15 @@ def _cmp(self, other) -> int:
         """Compare self to other point, returning a 'cmp'-like result."""
         pass
 
-    def standardise(self) -> 'PointBase':
-        """Format self.value into a standard representation and check it."""
+    def standardise(self, allow_truncated: bool = True) -> 'PointBase':
+        """Format self.value into a standard representation and check it.
+
+        Args:
+           allow_truncated:
+               If True, then truncated points (i.e. any point with context
+               missing off the front) will be tollerated, if False, truncated
+               points will cause an exception to be raised.
+        """
         return self
 
     @abstractmethod

cylc/flow/cycling/integer.py

@@ -145,7 +145,7 @@ def sub(self, other):
             return IntegerInterval.from_integer(int(self) - int(other))
         return IntegerPoint(int(self) - int(other))
 
-    def standardise(self):
+    def standardise(self, allow_truncated=True):
         """Format self.value into a standard representation and check it."""
         try:
             self.value = str(int(self))

cylc/flow/cycling/iso8601.py

@@ -92,9 +92,16 @@ def add(self, other):
             self.value, other.value, CALENDAR.mode
         ))
 
-    def standardise(self):
+    def standardise(self, allow_truncated=True):
         """Reformat self.value into a standard representation."""
         try:
+            point = point_parse(self.value)
+            if not allow_truncated and point.truncated:
+                raise PointParsingError(
+                    type(self),
+                    self.value,
+                    'Truncated ISO8601 dates are not permitted',
+                )
             self.value = str(point_parse(self.value))
         except IsodatetimeError as exc:
             if self.value.startswith("+") or self.value.startswith("-"):

cylc/flow/cycling/loader.py

@@ -158,13 +158,13 @@ def standardise_point_string(
 
 
 def standardise_point_string(
-    point_string: Optional[str], cycling_type: Optional[str] = None
+    point_string: Optional[str], cycling_type: Optional[str] = None,
 ) -> Optional[str]:
     """Return a standardised version of point_string."""
     if point_string is None:
         return None
     point = get_point(point_string, cycling_type=cycling_type)
     if point is not None:
-        point.standardise()
+        point.standardise(allow_truncated=False)
         point_string = str(point)
     return point_string

tests/integration/scripts/test_broadcast.py

@@ -134,3 +134,38 @@ async def test_broadcast_multi_namespace(
             ('*', 'VOWELS', 'execution time limit', 'PT5S'),
             ('*', 'root', 'execution time limit', 'PT5S'),
         ]
+
+
+async def test_broadcast_truncated_datetime(flow, scheduler, start, capsys):
+    """It should reject truncated datetime cycle points.
+
+    See https://github.com/cylc/cylc-flow/issues/6407
+    """
+    id_ = flow({
+        'scheduling': {
+            'initial cycle point': '2000',
+            'graph': {
+                'R1': 'foo',
+            },
+        }
+    })
+    schd = scheduler(id_)
+    async with start(schd):
+        # attempt an invalid broadcast
+        rets = await _main(
+            BroadcastOptions(
+                settings=['[environment]FOO=bar'],
+                point_strings=['050101T0000Z'],  # <== truncated
+            ),
+            schd.workflow,
+        )
+
+        # the broadcast should fail
+        assert list(rets.values()) == [False]
+
+        # an error should be recorded
+        _out, err = capsys.readouterr()
+        assert (
+            'Rejected broadcast:'
+            ' settings are not compatible with the workflow'
+        ) in err