Add tests for IntegrateCellArray

tests/CMakeLists.txt

@@ -98,6 +98,7 @@ add_executable (unit_tests
   test_GaussQuadratureDescriptor.cpp
   test_IfProcessor.cpp
   test_IncDecExpressionProcessor.cpp
+  test_IntegrateCellArray.cpp
   test_IntegrateCellValue.cpp
   test_IntegrateOnCells.cpp
   test_INodeProcessor.cpp