test: improve coverage of error termination status

Author: franckgaga

test/2_test_state_estim.jl

@@ -1035,6 +1035,16 @@ end
     info = getinfo(mhe5)
     @test info[:x̂] ≈ x̂ atol=1e-9
     @test info[:Ŷ][end-1:end] ≈ [50, 30] atol=1e-9
+
+    # coverage of the branch with error termination status (with an infeasible problem):
+    mhe_infeas = MovingHorizonEstimator(nonlinmodel, He=1, Cwt=Inf)
+    mhe_infeas = setconstraint!(mhe_infeas, v̂min=[1, 1], v̂max=[-1, -1]) 
+    @test_logs(
+        (:error, "MHE terminated without solution: estimation in open-loop "*
+                 "(more info in debug log)"), 
+        preparestate!(mhe_infeas, [0, 0], [0])
+    )
+
     # for coverage of NLP functions, the univariate syntax of JuMP.@operator
     mhe6 = MovingHorizonEstimator(nonlinmodel, He=1, Cwt=Inf)
     setconstraint!(mhe6, v̂min=[-51,-52], v̂max=[53,54])

test/3_test_predictive_control.jl

@@ -121,6 +121,16 @@ end
     ΔU_diff = diff(getinfo(mpc7)[:U])
     @test ΔU_diff[[2, 4, 5, 7, 8, 9]] ≈ zeros(6) atol=1e-9
 
+    # coverage of the branch with error termination status (with an infeasible problem):
+    mpc_infeas = LinMPC(linmodel2, Hp=1, Hc=1, Cwt=Inf)
+    mpc_infeas = setconstraint!(mpc_infeas, umin=[+1], umax=[-1])
+    preparestate!(mpc_infeas, [0], [0])
+    @test_logs(
+        (:error, "MPC terminated without solution: returning last solution shifted "*
+                 "(more info in debug log)"), 
+        moveinput!(mpc_infeas, [0], [0])
+    )
+
     @test_throws DimensionMismatch moveinput!(mpc1, [0,0,0])
     @test_throws DimensionMismatch moveinput!(mpc1, [0], [0,0])
     @test_throws DimensionMismatch moveinput!(mpc1; D̂  = fill(0, mpc1.Hp+1))
@@ -823,6 +833,17 @@ end
     ΔU_diff = diff(getinfo(nmpc11)[:U])
     @test ΔU_diff[[2, 4, 5, 7, 8, 9]] ≈ zeros(6) atol=1e-9
 
+    # coverage of the branch with error termination status (with an infeasible problem):
+    nmpc_infeas = NonLinMPC(nonlinmodel, Hp=1, Hc=1, Cwt=Inf)
+    nmpc_infeas = setconstraint!(nmpc_infeas, umin=[+1], umax=[-1])
+    preparestate!(nmpc_infeas, [0], [0])
+    @test_logs(
+        (:error, "MPC terminated without solution: returning last solution shifted "*
+                 "(more info in debug log)"), 
+        moveinput!(nmpc_infeas, [0], [0])
+    )
+
+
     @test_nowarn ModelPredictiveControl.info2debugstr(info)
 end