Minor fix

src/ifcopenshell-python/ifcopenshell/api/sequence/cascade_schedule.py

@@ -44,7 +44,7 @@ class Usecase:
                 else:
                     print("... is a predecessor to ...", debug_task)
             print("... which is cyclically a predecessor to ...", task)
-            raise Exception("Recursive tasks found. Could not cascade schedule.")
+            raise RecursionError("Recursive tasks found. Could not cascade schedule.")
 
         if not task.TaskTime:
             return

src/ifcopenshell-python/ifcopenshell/api/sequence/recalculate_schedule.py

@@ -62,7 +62,7 @@ class Usecase:
                 break # We have an infinite loop due to a cyclic graph
 
         if is_cyclic:
-            raise Exception("Task graph is cyclic and so critical path method cannot be performed.")
+            raise RecursionError("Task graph is cyclic and so critical path method cannot be performed.")
             return
 
         self.pending_nodes = set(self.g.nodes)

src/ifcopenshell-python/test/api/sequence/test_cascade_schedule.py

@@ -16,6 +16,7 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
+import pytest
 import datetime
 import test.bootstrap
 import ifcopenshell.api
@@ -53,6 +54,14 @@ class TestCascadeSchedule(test.bootstrap.IFC4):
         assert task3.TaskTime.ScheduleStart == "2000-01-02T09:00:00"
         assert task3.TaskTime.ScheduleFinish == "2000-01-04T17:00:00"
 
+    def test_catching_cyclic_relationships(self):
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        self._create_sequence(task, task2, "FINISH_START")
+        with pytest.raises(RecursionError):
+            self._create_sequence(task2, task, "FINISH_START")
+            ifcopenshell.api.run("sequence.cascade_schedule", self.file, task=task)
+
     def test_cascading_finish_to_start(self):
         task = self._create_task("P1D")
         task2 = self._create_task("P2D")

src/ifcopenshell-python/test/api/sequence/test_recalculate_schedule.py

@@ -16,6 +16,7 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
+import pytest
 import datetime
 import test.bootstrap
 import ifcopenshell.api
@@ -29,6 +30,20 @@ class TestRecalculateSchedule(test.bootstrap.IFC4):
         ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
         assert task.TaskTime is None
 
+    def test_catching_cyclic_relationships(self):
+        self._add_work_schedule()
+        task = self._create_task("P1D")
+        task2 = self._create_task("P2D")
+        task3 = self._create_task("P2D")
+        task4 = self._create_task("P2D")
+        self._create_sequence(task, task2, "FINISH_START")
+        self._create_sequence(task, task4, "FINISH_START")
+        self._create_sequence(task2, task3, "FINISH_START")
+        with pytest.raises(RecursionError):
+            self._create_sequence(task3, task2, "FINISH_START")
+        with pytest.raises(RecursionError):
+            ifcopenshell.api.run("sequence.recalculate_schedule", self.file, work_schedule=self.work_schedule)
+
     def test_recalculating_for_a_single_task(self):
         self._add_work_schedule()
         task = self._create_task("P1D")