Added stepped simulation test.

src/scenic/core/simulators.py

@@ -420,10 +420,6 @@ def __init__(
             # properties during setup.
             self.updateObjects()
 
-            # Set terminationType and terminationReason to default None
-            self.terminationType = None
-            self.terminationReason = None
-
         except (RejectSimulationException, RejectionException, GuardViolation) as e:
             # This simulation will be thrown out, but attach it to the exception
             # to aid in debugging.
@@ -437,11 +433,11 @@ def _run(self):
         while True:
             self.advance()
 
-            if self.terminationType:
+            if self.result:
                 return
 
     def advance(self):
-        if self.terminationType or self._cleaned:
+        if self.result or self._cleaned:
             raise TerminatedSimulationException()
 
         if self.verbosity >= 3:
@@ -543,13 +539,9 @@ def advance(self):
         self.currentTime += 1
         self.updateObjects()
 
-    def terminateSimulation(self, terimnationType, terminationReason):
+    def terminateSimulation(self, terminationType, terminationReason):
         import scenic.syntax.veneer as veneer
 
-        # Log terminationType and terminationReason
-        self.terminationType = terimnationType
-        self.terminationReason = terminationReason
-
         # Stop all remaining scenarios.
         # (and reject if some 'require eventually' condition was never satisfied)
         for scenario in tuple(reversed(veneer.runningScenarios)):
@@ -564,8 +556,8 @@ def terminateSimulation(self, terimnationType, terminationReason):
         result = SimulationResult(
             self.trajectory,
             self.actionSequence,
-            self.terminationType,
-            self.terminationReason,
+            terminationType,
+            terminationReason,
             self.records,
         )
         self.result = result

tests/core/test_simulators.py

@@ -1,6 +1,11 @@
 import pytest
 
-from scenic.core.simulators import DummySimulation, DummySimulator, Simulation
+from scenic.core.simulators import (
+    DummySimulation,
+    DummySimulator,
+    Simulation,
+    TerminatedSimulationException,
+)
 from tests.utils import compileScenic, sampleResultFromScene, sampleSceneFrom
 
 
@@ -35,6 +40,29 @@ def test_simulator_destruction():
     assert "destroy() called twice" in str(e)
 
 
+def test_simulator_stepped():
+    simulator = DummySimulator()
+    scene = sampleSceneFrom("ego = new Object")
+
+    with simulator.simulateStepped(scene, maxSteps=5) as simulation:
+        while simulation.result is None:
+            simulation.advance()
+
+        assert simulation.result is not None
+        assert simulation.currentTime == 5
+
+        # advance() should do nothing but raise an exception
+        # if the simulation is already terminated
+        with pytest.raises(TerminatedSimulationException):
+            simulation.advance()
+
+        assert simulation.currentTime == 5
+
+    # Ensure all values are preserved after leaving the context manager
+    assert simulation.result is not None
+    assert simulation.currentTime == 5
+
+
 def test_simulator_set_property():
     class TestSimulation(DummySimulation):
         def createObjectInSimulator(self, obj):