chore(tests): update ToBatchProcessor test

tests/processor/test_batch_processor.py

@@ -603,24 +603,6 @@ def test_action_dtype_preservation():
         assert result[TransitionKey.ACTION].shape == (1, 4)
 
 
-def test_action_in_place_mutation():
-    """Test that the processor mutates the transition in place for actions."""
-    processor = ToBatchProcessor()
-
-    action = torch.randn(4)
-    transition = create_transition(action=action)
-
-    # Store reference to original transition
-    original_transition = transition
-
-    # Process
-    result = processor(transition)
-
-    # Should be the same object (in-place mutation)
-    assert result is original_transition
-    assert result[TransitionKey.ACTION].shape == (1, 4)
-
-
 def test_empty_action_tensor():
     """Test handling of empty action tensors."""
     processor = ToBatchProcessor()
@@ -851,27 +833,6 @@ def test_task_comprehensive_string_cases():
         processed_comp_data = result[TransitionKey.COMPLEMENTARY_DATA]
         assert processed_comp_data["task"] == task_list
         assert isinstance(processed_comp_data["task"], list)
-        assert processed_comp_data["task"] is task_list  # Should be same object (in-place)
-
-
-def test_task_in_place_mutation():
-    """Test that the processor mutates complementary_data in place for tasks."""
-    processor = ToBatchProcessor()
-
-    complementary_data = {"task": "sort_objects"}
-    transition = create_transition(complementary_data=complementary_data)
-
-    # Store reference to original transition and complementary_data
-    original_transition = transition
-    original_comp_data = complementary_data
-
-    # Process
-    result = processor(transition)
-
-    # Should be the same objects (in-place mutation)
-    assert result is original_transition
-    assert result[TransitionKey.COMPLEMENTARY_DATA] is original_comp_data
-    assert original_comp_data["task"] == ["sort_objects"]
 
 
 def test_task_preserves_other_keys():
@@ -1127,3 +1088,49 @@ def test_empty_index_tensor():
 
     # Should remain unchanged (already 1D)
     assert result[TransitionKey.COMPLEMENTARY_DATA]["index"].shape == (0,)
+
+
+def test_action_processing_creates_new_transition():
+    """Test that the processor creates a new transition object with correctly processed action."""
+    processor = ToBatchProcessor()
+
+    action = torch.randn(4)
+    transition = create_transition(action=action)
+
+    # Store reference to original transition
+    original_transition = transition
+
+    # Process
+    result = processor(transition)
+
+    # Should be a different object (functional design, not in-place mutation)
+    assert result is not original_transition
+    # Original transition should remain unchanged
+    assert original_transition[TransitionKey.ACTION].shape == (4,)
+    # Result should have correctly processed action with batch dimension
+    assert result[TransitionKey.ACTION].shape == (1, 4)
+    assert torch.equal(result[TransitionKey.ACTION][0], action)
+
+
+def test_task_processing_creates_new_transition():
+    """Test that the processor creates a new transition object with correctly processed task."""
+    processor = ToBatchProcessor()
+
+    complementary_data = {"task": "sort_objects"}
+    transition = create_transition(complementary_data=complementary_data)
+
+    # Store reference to original transition and complementary_data
+    original_transition = transition
+    original_comp_data = complementary_data
+
+    # Process
+    result = processor(transition)
+
+    # Should be different transition object (functional design)
+    assert result is not original_transition
+    # But complementary_data is the same reference (current implementation behavior)
+    assert result[TransitionKey.COMPLEMENTARY_DATA] is original_comp_data
+    # The task should be processed correctly (wrapped in list)
+    assert result[TransitionKey.COMPLEMENTARY_DATA]["task"] == ["sort_objects"]
+    # Original complementary data is also modified (current behavior)
+    assert original_comp_data["task"] == ["sort_objects"]