Fix MIP solver variable duplication and function structure

test_mip.py

@@ -0,0 +1,50 @@
+"""
+Test script to verify MIP functionality
+"""
+
+import numpy as np
+import pandas as pd
+from mip import design_with_mip
+
+# Create test data
+np.random.seed(42)
+n_turbines = 10
+turbines = pd.DataFrame(
+    {
+        "x": np.random.uniform(0, 2000, n_turbines),
+        "y": np.random.uniform(0, 2000, n_turbines),
+        "power": np.random.uniform(5, 10, n_turbines),
+    }
+)
+
+substation = np.array([1000, 1000])
+
+print("Test data created:")
+print(f"Number of turbines: {n_turbines}")
+print(f"Substation location: {substation}")
+print(f"Total power: {turbines['power'].sum():.2f} MW")
+
+# Test MIP function
+print("\nTesting MIP design...")
+try:
+    connections, turbines_with_clusters = design_with_mip(
+        turbines,
+        substation,
+        cable_specs=None,
+        voltage=66000,
+        power_factor=0.95,
+        system_params=None,
+        max_clusters=None,
+        time_limit=30,
+        evaluate_func=None,
+        total_invest_func=None,
+        get_max_capacity_func=None,
+    )
+    print(f"MIP test successful!")
+    print(f"Number of connections: {len(connections)}")
+    print(f"Clusters assigned: {turbines_with_clusters['cluster'].tolist()}")
+except Exception as e:
+    print(f"MIP test failed with error: {e}")
+    import traceback
+
+    traceback.print_exc()