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added test for copyLargeNeighborhoodSearch and translateSubSol

Author: stefanmaak

tests/sub_sol_test.py

@@ -0,0 +1,59 @@
+"""
+Tests the usage of sub solutions found in heuristics with copyLargeNeighborhoodSearch()
+"""
+import pytest
+from pyscipopt import Model, Heur, SCIP_HEURTIMING, SCIP_RESULT
+
+
+class MyHeur(Heur):
+    def __init__(self, model: Model, fix_vars, fix_vals):
+        super().__init__()
+        self.original_model = model
+        self.used = False
+        self.fix_vars = fix_vars
+        self.fix_vals = fix_vals
+
+    def heurexec(self, heurtiming, nodeinfeasible):
+        print("Hello World")
+        self.used = True
+        # fix z to 2 and optimize the remaining problem
+        m2 = self.original_model.copyLargeNeighborhoodSearch(self.fix_vars, self.fix_vals)
+        m2.optimize()
+
+        # translate the solution to the original problem
+        sub_sol = m2.getBestSol()
+        sol_translation = self.original_model.translateSubSol(m2, sub_sol, self)
+
+        accepted = self.original_model.trySol(sol_translation)
+        assert accepted
+        m2.freeProb()
+        return {"result": SCIP_RESULT.FOUNDSOL}
+
+
+def test_sub_sol():
+    m = Model("sub_sol_test")
+    x = m.addVar(name="x", lb=0, ub=3, obj=1)
+    y = m.addVar(name="y", lb=0, ub=3, obj=2)
+    z = m.addVar(name="z", lb=0, ub=3, obj=3)
+
+    m.addCons(4 <= x + y + z)
+
+    # include the heuristic
+    my_heur = MyHeur(m, fix_vars= [z], fix_vals = [2])
+    m.includeHeur(my_heur, "name", "description", "Y", timingmask=SCIP_HEURTIMING.BEFOREPRESOL, usessubscip=True)
+
+    #optimize
+    m.optimize()
+    # assert the heuristic did run
+    assert my_heur.used
+
+    heur_sol = [2, 0, 2]
+    opt_sol = [3, 1, 0]
+
+    found_solutions = []
+    for sol in m.getSols():
+        found_solutions.append([sol[x], sol[y], sol[z]])
+
+    # both the sub_solution and the real optimum should be in the solution pool
+    assert heur_sol in found_solutions
+    assert opt_sol in found_solutions