Fix Issue #74: Add missing Grid.grid_y property

Added individual grid_x and grid_y getter properties to the Grid class
to complement the existing grid_size property. This allows direct access
to grid dimensions and fixes error messages that referenced these
properties before they existed.

closes #74

tests/issue74_grid_xy_properties_test.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+"""
+Test for Issue #74: Add missing Grid.grid_y property
+
+Verifies that Grid objects expose grid_x and grid_y properties correctly.
+"""
+
+def test_grid_xy_properties(timer_name):
+    """Test that Grid has grid_x and grid_y properties"""
+    import mcrfpy
+    
+    # Test was run
+    print("Issue #74 test: Grid.grid_x and Grid.grid_y properties")
+    
+    # Test with texture
+    texture = mcrfpy.Texture("assets/kenney_ice.png", 16, 16)
+    grid = mcrfpy.Grid(20, 15, texture, (0, 0), (800, 600))
+    
+    # Test grid_x property
+    assert hasattr(grid, 'grid_x'), "Grid should have grid_x property"
+    assert grid.grid_x == 20, f"Expected grid_x=20, got {grid.grid_x}"
+    print(f"✓ grid.grid_x = {grid.grid_x}")
+    
+    # Test grid_y property
+    assert hasattr(grid, 'grid_y'), "Grid should have grid_y property"
+    assert grid.grid_y == 15, f"Expected grid_y=15, got {grid.grid_y}"
+    print(f"✓ grid.grid_y = {grid.grid_y}")
+    
+    # Test grid_size still works
+    assert hasattr(grid, 'grid_size'), "Grid should still have grid_size property"
+    assert grid.grid_size == (20, 15), f"Expected grid_size=(20, 15), got {grid.grid_size}"
+    print(f"✓ grid.grid_size = {grid.grid_size}")
+    
+    # Test without texture
+    grid2 = mcrfpy.Grid(30, 25, None, (10, 10), (480, 400))
+    assert grid2.grid_x == 30, f"Expected grid_x=30, got {grid2.grid_x}"
+    assert grid2.grid_y == 25, f"Expected grid_y=25, got {grid2.grid_y}"
+    assert grid2.grid_size == (30, 25), f"Expected grid_size=(30, 25), got {grid2.grid_size}"
+    print("✓ Grid without texture also has correct grid_x and grid_y")
+    
+    # Test using in error message context (original issue)
+    try:
+        grid.at((-1, 0))  # Should raise error
+    except ValueError as e:
+        error_msg = str(e)
+        assert "Grid.grid_x" in error_msg, f"Error message should reference Grid.grid_x: {error_msg}"
+        print(f"✓ Error message correctly references Grid.grid_x: {error_msg}")
+    
+    try:
+        grid.at((0, -1))  # Should raise error
+    except ValueError as e:
+        error_msg = str(e)
+        assert "Grid.grid_y" in error_msg, f"Error message should reference Grid.grid_y: {error_msg}"
+        print(f"✓ Error message correctly references Grid.grid_y: {error_msg}")
+    
+    print("\n✅ Issue #74 test PASSED - Grid.grid_x and Grid.grid_y properties work correctly")
+
+# Execute the test after a short delay to ensure window is ready
+import mcrfpy
+mcrfpy.setTimer("test_timer", test_grid_xy_properties, 100)