Update initial condition unit test

Add test case for initial condition from H5 data file

dune/dorie/test/test-initial-condition.cc

@@ -72,6 +72,15 @@ void test_ic_base (const std::shared_ptr<typename T::Grid> grid,
         };
         test_ic_against_function(grid, ic, test_f);
     }
+    else if (type == "file") {
+        // define testing function
+        auto test_f = [](const auto e, const auto x){
+            using Range = typename T::Scalar;
+            Range y = 2.0;
+            return y;
+        };
+        test_ic_against_function(grid, ic, test_f);
+    }
 }
 
 int main (int argc, char** argv)

dune/dorie/test/test-initial-condition.mini.in

 include ${CMAKE_BINARY_DIR}/doc/default_files/config.ini
 
-__name = ic
+_initial_type = linear, data | expand
+__name = {_initial_type}
 _asset_path = "${PROJECT_SOURCE_DIR}/test"
 
 [grid]
@@ -14,7 +15,12 @@ extensions = 1 1
 file = none
 
 [richards.initial]
-type = linear
+type = {_initial_type}
+
 quantity = matricHead
 headLower = -1.0
 headGradient = 2.0
+
+file = ${CMAKE_CURRENT_LIST_DIR}/scaling.h5
+dataset = twos
+interpolation = nearest