improve coverage

Author: mateuszbaran

src/plans/box_plan.jl

@@ -337,9 +337,9 @@ abstract type AbstractFPFPPUpdater end
     init_updater!(::AbstractManifold, fpfpp_upd::AbstractFPFPPUpdater, p, d, ha::AbstractQuasiNewtonDirectionUpdate)
 
 Method for initialization of `AbstractFPFPPUpdater` `fpfpp_upd` just before the loop
-that examines subsequent intervals for GCP. By default it does nothing.
+that examines subsequent intervals for GCP.
 """
-init_updater!(::AbstractManifold, fpfpp_upd::AbstractFPFPPUpdater, p, d, ha::AbstractQuasiNewtonDirectionUpdate) = fpfpp_upd
+init_updater!(::AbstractManifold, fpfpp_upd::AbstractFPFPPUpdater, p, d, ha::AbstractQuasiNewtonDirectionUpdate)
 
 """
     struct GenericFPFPPUpdater <: AbstractFPFPPUpdater end

test/solvers/test_quasi_Newton_box.jl

@@ -175,6 +175,11 @@ using RecursiveArrayTools
         @test Manopt.find_generalized_cauchy_point_direction!(gf, d_out, p, d, X1) === :found_limited
         @test d_out ≈ [2.0, 0.0, 0.0]
 
+
+        d_out = similar(d)
+
+        @test Manopt.find_generalized_cauchy_point_direction!(gf, d_out, p, 0 * d, X1) === :not_found
+
         d2 = [0.0, 1.0, 0.0]
 
         @test Manopt.find_generalized_cauchy_point_direction!(gf, d_out, p, d2, [0.0, -1.0, 0.0]) === :found_unlimited