From a4eda3d1425e8f5031f684ffcd9c3fb09f2e3615 Mon Sep 17 00:00:00 2001
From: wout4 <wout.vanroose@gmail.com>
Date: Wed, 6 Sep 2023 15:05:56 +0200
Subject: [PATCH] added test

---
 cpmpy/solvers/gurobi.py |  8 +++++---
 tests/test_solvers.py   | 11 +++++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/cpmpy/solvers/gurobi.py b/cpmpy/solvers/gurobi.py
index 417af2da0..10f6ee3c5 100644
--- a/cpmpy/solvers/gurobi.py
+++ b/cpmpy/solvers/gurobi.py
@@ -337,11 +337,13 @@ def __add__(self, cpm_expr_orig):
                     #integer division is not the same as floordivision, so we need to use continuous variables
                     cont_a = self.grb_model.addVar(x.lb, x.ub, vtype=GRB.CONTINUOUS, name=str(x.name) + '_cont')
                     cont_rhs = self.grb_model.addVar(rhs.lb, rhs.ub, vtype=GRB.CONTINUOUS, name=str(rhs.name) + '_cont')
+                    abs_rhs = self.grb_model.addVar(rhs.lb, rhs.ub, vtype=GRB.CONTINUOUS, name=str(rhs.name) + '_cont_abs')
                     self.grb_model.addLConstr(cont_a/b, GRB.EQUAL, cont_rhs)
                     self.grb_model.addConstr(cont_a == a)
-                    #grbrhs is the result of integer division, so it's the rounded down version of cont_rhs
-                    self.grb_model.addLConstr(cont_rhs - grbrhs, GRB.LESS_EQUAL, 0.999999) #closest we can get to 1
-                    self.grb_model.addLConstr(grbrhs - cont_rhs, GRB.LESS_EQUAL, 0)
+                    #grbrhs is the result of integer division, so it's the rounded towards 0 version of cont_rhs
+                    self.grb_model.addGenConstrAbs(abs_rhs, cont_rhs)
+                    self.grb_model.addLConstr(abs_rhs - grbrhs, GRB.LESS_EQUAL, 0.99999) #closest we can get to 1
+                    self.grb_model.addLConstr(grbrhs - abs_rhs, GRB.LESS_EQUAL, 0)
 
                 else:
                     # General constraints
diff --git a/tests/test_solvers.py b/tests/test_solvers.py
index e8f06849b..acf6fb396 100644
--- a/tests/test_solvers.py
+++ b/tests/test_solvers.py
@@ -555,3 +555,14 @@ def test_gurobi_element(self):
         s = cp.SolverLookup.get("gurobi", model)
         self.assertTrue(s.solve())
         self.assertTrue(iv.value()[idx.value(), idx2.value()] == 8)
+
+    @pytest.mark.skipif(not CPM_gurobi.supported(),
+                        reason="Gurobi not installed")
+    def test_gurobi_element(self):
+        iv = cp.intvar(-1, 3, shape=3)
+        x1 = cp.intvar(0, 3, name="x1")
+        cons = [x1 // 2 == iv, x1 > 0]
+        m = cp.Model(cons)
+        self.assertEqual(m.solveAll('gurobi', solution_limit=90),m.solveAll)
+        print('___')
+        Model(cons).solveAll(display=[x1, iv])
\ No newline at end of file