Fix terrain unittest on GPU

amr-wind/physics/TerrainDrag.cpp

@@ -174,13 +174,4 @@ void TerrainDrag::pre_init_actions()
 {
     BL_PROFILE("amr-wind::" + this->identifier() + "::pre_init_actions");
 }
-
-int TerrainDrag::return_blank_value(int i, int j, int k)
-{
-    int lev = 0;
-    amrex::MFIter mfi(m_terrain_blank(lev));
-    const auto& terrain_blank = m_terrain_blank(lev).const_array(mfi);
-    return int(terrain_blank(i, j, k));
-}
-
 } // namespace amr_wind::terraindrag

unit_tests/aw_test_utils/test_utils.H

@@ -143,6 +143,63 @@ inline void field_minmax(
     field_max(nlevels, field, max_val);
 }
 
+template <typename T, typename FType>
+inline T field_probe_impl(
+    const FType& field,
+    const int lev,
+    const int i,
+    const int j,
+    const int k,
+    const int icomp = 0)
+{
+    const amrex::IntVect iv_val = {i, j, k};
+    T value = amrex::ReduceSum(
+        field(lev), 0,
+        [=] AMREX_GPU_HOST_DEVICE(
+            amrex::Box const& bx,
+            amrex::Array4<T const> const& field_arr) -> T {
+            T val = 0.0;
+
+            if (bx.contains(iv_val)) {
+                amrex::Loop(bx, [=, &val](int i0, int j0, int k0) noexcept {
+                    const amrex::IntVect iv = {i0, j0, k0};
+                    if (iv == iv_val) {
+                        val = field_arr(iv, icomp);
+                    }
+                });
+            }
+            return val;
+        });
+    return value;
+}
+
+inline int field_probe(
+    const amr_wind::IntField& field,
+    const int lev,
+    const int i,
+    const int j,
+    const int k,
+    const int icomp = 0)
+{
+    int value = field_probe_impl<int>(field, lev, i, j, k, icomp);
+    amrex::ParallelDescriptor::ReduceIntSum(value);
+    return value;
+}
+
+inline amrex::Real field_probe(
+    const amr_wind::Field& field,
+    const int lev,
+    const int i,
+    const int j,
+    const int k,
+    const int icomp = 0)
+{
+    amrex::Real value =
+        field_probe_impl<amrex::Real>(field, lev, i, j, k, icomp);
+    amrex::ParallelDescriptor::ReduceRealSum(value);
+    return value;
+}
+
 } // namespace amr_wind_tests::utils
 
 #endif /* TEST_UTILS_H */

unit_tests/wind_energy/test_abl_terrain.cpp

@@ -65,13 +65,13 @@ TEST_F(TerrainTest, terrain)
     pp.addarr("physics", physics);
     amr_wind::terraindrag::TerrainDrag terrain_drag(sim());
     terrain_drag.post_init_actions();
-    int value = 100;
+    const auto& terrain_blank = sim().repo().get_int_field("terrain_blank");
     // Outside Point
-    value = terrain_drag.return_blank_value(5, 5, 1);
-    EXPECT_EQ(value, tol);
+    const int value_out = utils::field_probe(terrain_blank, 0, 5, 5, 1);
+    EXPECT_EQ(value_out, tol);
     // Inside Point
-    value = terrain_drag.return_blank_value(15, 10, 1);
-    EXPECT_EQ(value, 1 + tol);
+    const int value_in = utils::field_probe(terrain_blank, 0, 15, 10, 1);
+    EXPECT_EQ(value_in, 1 + tol);
 }
 
 } // namespace amr_wind_tests