Composition: set most_recent_context in execute (#3195)

- other Components generally set in their execute methods
- setting only in Composition.run fails to set when a Composition is
nested, because only execute gets called
- must still be set in Composition.run in case Composition is empty

Author: kmantel

psyneulink/core/compositions/composition.py

@@ -12689,6 +12689,8 @@ def execute(
 
             execution_scheduler.get_clock(context)._increment_time(TimeScale.TRIAL)
 
+            self.most_recent_context = context
+
             # Extract result here
             if execution_mode.is_compiled():
                 assert execution_mode & pnlvm.ExecutionMode._PerNode

psyneulink/library/compositions/autodiffcomposition.py

@@ -1525,6 +1525,7 @@ def execute(self,
 
                 scheduler.get_clock(context)._increment_time(TimeScale.TRIAL)
 
+                self.most_recent_context = context
                 return all_output_values
 
         # Call Composition execute in Python mode

tests/composition/test_composition.py

@@ -8397,6 +8397,48 @@ def test_rebuild_scheduler_after_remove_node(self):
         assert comp.scheduler.execution_list[comp.default_execution_id] == [{A}, {A}, {C}]
         assert set(comp.scheduler._user_specified_conds.conditions.keys()) == {C}
 
+    # empty pathway bypasses call to .execute, but most_recent_context
+    # should still be set
+    @pytest.mark.parametrize(
+        'inner_pathway',
+        [
+            pytest.param([ProcessingMechanism()], id='1_mech'),
+            pytest.param([], id='empty'),
+        ]
+    )
+    def test_most_recent_context_nested(self, inner_pathway):
+        inner = pnl.Composition(name='inner', pathways=inner_pathway)
+        outer = pnl.Composition(name='outer')
+        outer.add_node(inner)
+
+        assert outer.most_recent_context.execution_id is None
+        assert inner.most_recent_context.execution_id is None
+
+        inner.run()
+        assert outer.most_recent_context.execution_id is None
+        assert inner.most_recent_context.execution_id == inner.name
+
+        if len(inner_pathway) == 0:
+            with pytest.raises(
+                pnl.MechanismError,
+                match=r'Number of inputs \(1\) to inner Output_CIM does not match its number of input_ports \(0\)'
+            ) as e:
+                outer.run()
+            if e:
+                pytest.xfail(
+                    reason='running outer comp with empty inner comp fails validation'
+                )
+        else:
+            outer.run()
+            assert outer.most_recent_context.execution_id == outer.name
+            assert inner.most_recent_context.execution_id == outer.name
+
+        # COMMAND_LINE to bypass check for input passed to nested comp
+        c = pnl.Context(source=pnl.ContextFlags.COMMAND_LINE)
+        inner.run(context=c)
+        assert outer.most_recent_context.execution_id == outer.name
+        assert inner.most_recent_context.execution_id == c.execution_id
+
 
 class TestInputSpecsDocumentationExamples: