Implement Entity.index() method for Issue #73

Added index() method to Entity class that returns the entity's
position in its parent grid's entity collection. This enables
proper entity removal patterns using entity.index().

tests/issue73_entity_index_test.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+"""
+Test for Issue #73: Entity.index() method for removal
+
+Verifies that Entity objects can report their index in the grid's entity collection.
+"""
+
+def test_entity_index(timer_name):
+    """Test that Entity.index() method works correctly"""
+    import mcrfpy
+    import sys
+    
+    print("Issue #73 test: Entity.index() method")
+    
+    # Create test scene and grid
+    mcrfpy.createScene("test")
+    ui = mcrfpy.sceneUI("test")
+    
+    # Create grid with texture
+    texture = mcrfpy.Texture("assets/kenney_ice.png", 16, 16)
+    grid = mcrfpy.Grid(10, 10, texture, (10, 10), (400, 400))
+    ui.append(grid)
+    
+    # Create multiple entities
+    entities = []
+    for i in range(5):
+        entity = mcrfpy.Entity((i, i), texture, i, grid)
+        entities.append(entity)
+        grid.entities.append(entity)
+    
+    print(f"✓ Created {len(entities)} entities")
+    
+    # Test 1: Check each entity knows its index
+    for expected_idx, entity in enumerate(entities):
+        try:
+            actual_idx = entity.index()
+            assert actual_idx == expected_idx, f"Expected index {expected_idx}, got {actual_idx}"
+            print(f"✓ Entity {expected_idx} correctly reports index {actual_idx}")
+        except Exception as e:
+            print(f"✗ Entity {expected_idx} index() failed: {e}")
+            raise
+    
+    # Test 2: Remove entity using index
+    entity_to_remove = entities[2]
+    remove_idx = entity_to_remove.index()
+    grid.entities.remove(remove_idx)
+    print(f"✓ Removed entity at index {remove_idx}")
+    
+    # Test 3: Verify indices updated after removal
+    for i, entity in enumerate(entities):
+        if i == 2:
+            # This entity was removed, should raise error
+            try:
+                idx = entity.index()
+                print(f"✗ Removed entity still reports index {idx}")
+            except ValueError as e:
+                print(f"✓ Removed entity correctly raises error: {e}")
+        elif i < 2:
+            # These entities should keep their indices
+            idx = entity.index()
+            assert idx == i, f"Entity before removal has wrong index: {idx}"
+        else:
+            # These entities should have shifted down by 1
+            idx = entity.index()
+            assert idx == i - 1, f"Entity after removal has wrong index: {idx}"
+    
+    # Test 4: Entity without grid
+    orphan_entity = mcrfpy.Entity((0, 0), texture, 0, None)
+    try:
+        idx = orphan_entity.index()
+        print(f"✗ Orphan entity should raise error but returned {idx}")
+    except RuntimeError as e:
+        print(f"✓ Orphan entity correctly raises error: {e}")
+    
+    # Test 5: Use index() in practical removal pattern
+    # Add some new entities
+    for i in range(3):
+        entity = mcrfpy.Entity((7+i, 7+i), texture, 10+i, grid)
+        grid.entities.append(entity)
+    
+    # Remove entities with sprite_number > 10
+    removed_count = 0
+    i = 0
+    while i < len(grid.entities):
+        entity = grid.entities[i]
+        if entity.sprite_number > 10:
+            grid.entities.remove(entity.index())
+            removed_count += 1
+            # Don't increment i, as entities shifted down
+        else:
+            i += 1
+    
+    print(f"✓ Removed {removed_count} entities using index() in loop")
+    assert len(grid.entities) == 5, f"Expected 5 entities remaining, got {len(grid.entities)}"
+    
+    print("\n✅ Issue #73 test PASSED - Entity.index() method works correctly")
+    sys.exit(0)
+
+# Execute the test after a short delay
+import mcrfpy
+mcrfpy.setTimer("test", test_entity_index, 100)

tests/issue73_simple_index_test.py

@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+"""
+Simple test for Issue #73: Entity.index() method
+"""
+
+def test_entity_index(timer_name):
+    """Test that Entity.index() method works correctly"""
+    import mcrfpy
+    import sys
+    
+    print("Testing Entity.index() method...")
+    
+    # Create test scene and grid
+    mcrfpy.createScene("test")
+    ui = mcrfpy.sceneUI("test")
+    
+    # Create grid with texture
+    texture = mcrfpy.Texture("assets/kenney_ice.png", 16, 16)
+    grid = mcrfpy.Grid(10, 10, texture, (10, 10), (400, 400))
+    ui.append(grid)
+    
+    # Clear any existing entities
+    while len(grid.entities) > 0:
+        grid.entities.remove(0)
+    
+    # Create entities
+    entity1 = mcrfpy.Entity((1, 1), texture, 1, grid)
+    entity2 = mcrfpy.Entity((2, 2), texture, 2, grid)
+    entity3 = mcrfpy.Entity((3, 3), texture, 3, grid)
+    
+    grid.entities.append(entity1)
+    grid.entities.append(entity2)
+    grid.entities.append(entity3)
+    
+    print(f"Created {len(grid.entities)} entities")
+    
+    # Test index() method
+    idx1 = entity1.index()
+    idx2 = entity2.index()
+    idx3 = entity3.index()
+    
+    print(f"Entity 1 index: {idx1}")
+    print(f"Entity 2 index: {idx2}")
+    print(f"Entity 3 index: {idx3}")
+    
+    assert idx1 == 0, f"Entity 1 should be at index 0, got {idx1}"
+    assert idx2 == 1, f"Entity 2 should be at index 1, got {idx2}"
+    assert idx3 == 2, f"Entity 3 should be at index 2, got {idx3}"
+    
+    print("✓ All entities report correct indices")
+    
+    # Test removal using index
+    remove_idx = entity2.index()
+    grid.entities.remove(remove_idx)
+    print(f"✓ Removed entity at index {remove_idx}")
+    
+    # Check remaining entities
+    assert len(grid.entities) == 2
+    assert entity1.index() == 0
+    assert entity3.index() == 1  # Should have shifted down
+    
+    print("✓ Indices updated correctly after removal")
+    
+    # Test entity not in grid
+    orphan = mcrfpy.Entity((5, 5), texture, 5, None)
+    try:
+        idx = orphan.index()
+        print(f"✗ Orphan entity should raise error but returned {idx}")
+    except RuntimeError as e:
+        print(f"✓ Orphan entity correctly raises error")
+    
+    print("\n✅ Entity.index() test PASSED")
+    sys.exit(0)
+
+# Execute the test after a short delay
+import mcrfpy
+mcrfpy.setTimer("test", test_entity_index, 100)