Add basic unit test for density

src/general/density_calculators.jl

@@ -69,8 +69,7 @@ function summation_density!(system, system_index, semi, u, u_ode, density;
         # Loop over all pairs of particles and neighbors within the kernel cutoff.
         for_particle_neighbor(system, neighbor_system, system_coords, neighbor_coords,
                               neighborhood_search,
-                              particles=particles) do particle,
-                                                      neighbor, pos_diff, distance
+                              particles=particles) do particle, neighbor, pos_diff, distance
             mass = hydrodynamic_mass(neighbor_system, neighbor)
             density[particle] += mass * smoothing_kernel(system, distance)
         end

test/general/density_calculator.jl

@@ -1,26 +1,25 @@
 using OrdinaryDiffEq
 
-# setup a single particle and calculate its density
+# Setup a single particle and calculate its density
 @testset verbose=true "DensityCalculators" begin
     @testset verbose=true "SummationDensity" begin
         water_density = 1000.0
 
         # use reshape to create a matrix
-        init = InitialCondition(reshape([0.0, 0.0], 2, 1), reshape([0.0, 0.0], 2, 1),
-                                [water_density], [water_density])
+        initial_condition = InitialCondition(zeros(2, 1), zeros(2, 1), [water_density],
+                                             [water_density])
 
         smoothing_length = 1.0
         smoothing_kernel = SchoenbergCubicSplineKernel{2}()
 
         state_equation = StateEquationCole(10, 7, water_density, 100000.0,
-                                           background_pressure=100000.0,
-                                           clip_negative_pressure=false)
+                                           background_pressure=100000.0)
         viscosity = ArtificialViscosityMonaghan(0.02, 0.0)
 
-        fluid_system = WeaklyCompressibleSPHSystem(init, SummationDensity(), state_equation,
+        fluid_system = WeaklyCompressibleSPHSystem(initial_condition, SummationDensity(),
+                                                   state_equation,
                                                    smoothing_kernel, smoothing_length,
-                                                   viscosity=viscosity,
-                                                   acceleration=(0.0, 0.0))
+                                                   viscosity=viscosity)
 
         (; cache) = fluid_system
         (; density) = cache # Density is in the cache for SummationDensity
@@ -30,12 +29,7 @@ using OrdinaryDiffEq
 
         tspan = (0.0, 0.01)
         ode = semidiscretize(semi, tspan)
-
-        sol = solve(ode, RDPK3SpFSAL49(),
-                    abstol=1e-5, # Default abstol is 1e-6 (may need to be tuned to prevent boundary penetration)
-                    reltol=1e-3, # Default reltol is 1e-3 (may need to be tuned to prevent boundary penetration)
-                    dtmax=1e-2, # Limit stepsize to prevent crashing
-                    save_everystep=false)
+        TrixiParticles.update_systems_and_nhs(ode.u0.x..., semi, 0.0)
 
         @test density[1] ===
               water_density * TrixiParticles.kernel(smoothing_kernel, 0.0, smoothing_length)