[test][richards][parallel][lens] Use istl solver factory backend

test/porousmediumflow/richards/implicit/lens/main.cc

@@ -38,7 +38,7 @@
 #include <dumux/common/valgrind.hh>
 #include <dumux/common/dumuxmessage.hh>
 
-#include <dumux/linear/amgbackend.hh>
+#include <dumux/linear/genericistlbackend.hh>
 #include <dumux/porousmediumflow/richards/newtonsolver.hh>
 
 #include <dumux/assembly/fvassembler.hh>
@@ -143,7 +143,7 @@ int main(int argc, char** argv) try
     auto assembler = std::make_shared<Assembler>(problem, gridGeometry, gridVariables, timeLoop, xOld);
 
     // the linear solver
-    using LinearSolver = Dumux::AMGBackend<TypeTag>;
+    using LinearSolver = Dumux::GenericIstlBackend<TypeTag>;
     auto linearSolver = std::make_shared<LinearSolver>(leafGridView, gridGeometry->dofMapper());
 
     // the non-linear solver

test/porousmediumflow/richards/implicit/lens/params.input

@@ -8,8 +8,13 @@ Cells = 24 16
 
 [Problem]
 Name = richardslens
-EnableGravity = 1 # enable gravity
+EnableGravity = true # enable gravity
 
 [Newton]
 TargetSteps = 18 # set the "desirable" number of Newton iterations of a time step
 EnableChop = true # chop for better convergence
+
+[LinearSolver]
+Type = bicgstabsolver
+PreconditionerType = amg
+AmgMaxLevel = 2