Consistently silence output from solvers.

We adopt the solution outlined by @odow in jump-dev/JuMP.jl#1883 (comment).

src/MIPVerify.jl

@@ -98,6 +98,7 @@ function find_adversarial_example(
     tightening_algorithm::TighteningAlgorithm = DEFAULT_TIGHTENING_ALGORITHM,
     tightening_options::Dict = get_default_tightening_options(optimizer),
     solve_if_predicted_in_targeted = true,
+    silence_output = false,
 )::Dict
 
     total_time = @elapsed begin
@@ -150,6 +151,9 @@ function find_adversarial_example(
             end
             set_optimizer(m, optimizer)
             set_optimizer_attributes(m, main_solve_options...)
+            if silence_output
+                set_silent(m)
+            end
             optimize!(m)
             d[:SolveStatus] = JuMP.termination_status(m)
             d[:SolveTime] = JuMP.solve_time(m)

test/TestHelpers.jl

@@ -27,22 +27,24 @@ const TEST_DEFAULT_TIGHTENING_ALGORITHM = lp
 if Base.find_package("Gurobi") === nothing
     using Cbc
     optimizer = Cbc.Optimizer
-    main_solve_options = Dict("logLevel" => 0)
-    tightening_options = Dict("logLevel" => 0, "seconds" => 20)
+    main_solve_options = Dict()
+    tightening_options = Dict("seconds" => 20)
 else
     using Gurobi
     env = Gurobi.Env()
     optimizer = () -> Gurobi.Optimizer(env)
-    main_solve_options = Dict("OutputFlag" => 0)
-    tightening_options = Dict("OutputFlag" => 0, "TimeLimit" => 20)
+    main_solve_options = Dict()
+    tightening_options = Dict("TimeLimit" => 20)
 end
 
 get_optimizer() = optimizer
 get_main_solve_options()::Dict = main_solve_options
 get_tightening_options()::Dict = tightening_options
 
 function get_new_model()::Model
-    return Model(optimizer_with_attributes(get_optimizer(), get_main_solve_options()...))
+    m = Model(optimizer_with_attributes(get_optimizer(), get_main_solve_options()...))
+    set_silent(m)
+    return m
 end
 
 """
@@ -75,6 +77,7 @@ function test_find_adversarial_example(
         tightening_options = get_tightening_options(),
         tightening_algorithm = TEST_DEFAULT_TIGHTENING_ALGORITHM,
         invert_target_selection = invert_target_selection,
+        silence_output = true,
     )
     if isnan(expected_objective_value)
         @test d[:SolveStatus] == MathOptInterface.INFEASIBLE ||