Update gtest_helper.cmake

This updates the add_icon_c_test macro in cmake/gtest_helper.cmake:

1. The macro is turned into a function to avoid namespace pollution.
2. The function is renamed to fs_add_c_test.
3. The function now accepts named options SOURCES (followed by a list of source files of the test) and ARGS (followed by a list of command-line arguments for the test).
4. The old signature of the macro is still supported, i.e. it is possible to call something like add_c_test(UtilHashTest ctest_util_hash.cpp), but it made sense to me to switch to the new one.
5. The UtilFileTest test is now provided with an extra command-line argument and it runs on ${CMAKE_CURRENT_BINARY_DIR} instead of . as it was before !28 (merged).

cmake/gtest_helper.cmake

@@ -10,23 +10,31 @@
 # ---------------------------------------------------------------
 
 # cmake-format: off
-# add_icon_c_test(<test>
-#                 <source>)
+# fs_add_c_test(<test_name>
+#               [SOURCES <sources>]
+#               [ARGS <args>])
 # cmake-format: on
 # -----------------------------------------------------------------------------
-# Compiles a test executable with the name <test> using the source code
-# <source>. The googletest and fortran-support libraries will be linked
-# automatically.
+# Compiles a test executable with the name <test_name> using the source code
+# <source>. Specify ctest arguments in <args> if necessary. The googletest and
+# libfortran-support libraries will be linked automatically.
 #
 # The C++ standard is set to C++17.
 #
-macro(add_icon_c_test test_name file_name)
-  add_executable("CTest_${test_name}" ${file_name})
+function(fs_add_c_test test_name)
+
+  cmake_parse_arguments(PARSE_ARGV 1 ARG "" "" "SOURCES;ARGS")
+  if(NOT ARG_SOURCES)
+    set(ARG_SOURCES "${ARG_UNPARSED_ARGUMENTS}")
+  endif()
+
+  add_executable("CTest_${test_name}" ${ARG_SOURCES})
   target_link_libraries(
     "CTest_${test_name}" PRIVATE fortran-support::fortran-support
-                                 GTest::gtest_main)
-  add_test(NAME "CTest_${test_name}" COMMAND "CTest_${test_name}")
+                                 GTest::gtest_main stdc++fs)
+  add_test(NAME "CTest_${test_name}" COMMAND "CTest_${test_name}" ${ARG_ARGS})
   set_property(TEST "CTest_${test_name}" PROPERTY LABELS C)
   set_target_properties("CTest_${test_name}"
                         PROPERTIES CXX_STANDARD 17 CXX_STANDARD_REQUIRED ON)
-endmacro()
+
+endfunction()