Add test

Author: blegat

test/FlatZinc/model.jl

@@ -7,6 +7,10 @@
     @testset "Supported constraints" begin
         m = CP.FlatZinc.Model()
 
+        @test MOI.supports(
+            m,
+	    MOI.ObjectiveFunction{MOI.VariableIndex}(),
+        )
         @test MOI.supports_constraint(
             m,
             MOI.VariableIndex,
@@ -105,4 +109,4 @@
         @test MOI.supports_add_constrained_variable(m, S)
         @test MOI.supports_add_constrained_variables(m, S)
     end
-end
+end