chore: eliminate registerTests cmake module (from project-template)

This module is used in this one instance only, hence there is no justification to make it part of the project-template. The module is a lot more complicated than necessary (partialy due to the flawed attempt to make it generic). Simplifiction and cleanup can be done in a separate step.

Note: The project does not compile on Ubuntu 20.04, but it does not do so even without these modifications!

tests/test_executables/CMakeLists.txt

-include(registerTests)
+include(CMakeParseArguments)
+
+# FIXME: Cleanup and simplify!
+
+# >>> former cmake "module" registerTests begins here >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+#
+# usage:
+# register_tests(SOURCES
+#                  ${list_of_source_files}
+#                  "test_src.cc"
+#                  ${concatenated_string_of_source_files}
+#                NAMESPACE
+#                  "test_namespace"
+#                LINK_LIBRARIES
+#                  ${list_of_targets}
+#                INCLUDE_DIRECTORIES
+#                  ${list_of_include_directories}
+#                COMPILE_OPTIONS
+#                  ${list_of_compile_options}
+#                WORKING_DIRECTORY
+#                  ${ctest_working_directory})
+# 
+# Function registers tests defined as a list of souce files.  Test
+# defined by file source_name.cc in the SOURCES list is registered under
+# the name
+#   test_namespace.source_name
+#
+# If provided, test executables will use ${ctest_working_directory}
+# as the working directory
+#
+# Provided list of dependent link targets and include directories are
+# used as PRIVATE dependencies during compilation of test executable.
+# 
+# Function implicitly adds a dependency on the boost unit test framework
+# to each generated test executable.
+function(register_tests)
+  find_package(Boost COMPONENTS unit_test_framework REQUIRED)
+
+  list(APPEND single_parmeter_keywords NAMESPACE WORKING_DIRECTORY)
+  list(APPEND multi_parmeter_keywords SOURCES 
+                                      LINK_LIBRARIES
+                                      INCLUDE_DIRECTORIES 
+                                      COMPILE_OPTIONS)
+  cmake_parse_arguments("arg" "" "${single_parmeter_keywords}"
+                        "${multi_parmeter_keywords}" "${ARGN}")
+
+
+  register_exe(SOURCES "${arg_SOURCES}" 
+               NAMESPACE "${arg_NAMESPACE}"
+               WORKING_DIRECTORY "${arg_WORKING_DIRECTORY}")
+
+  get_test_targets(list_of_targets "${arg_SOURCES}")
+  
+  add_target_includes_private(TARGETS "${list_of_targets}" 
+                              LINK_LIBRARIES "${arg_INCLUDE_DIRECTORIES}" 
+                              "${Boost_INCLUDE_DIR}")
+
+  add_target_link_libraries_private(TARGETS "${list_of_targets}" 
+                                    LINK_LIBRARIES "${Boost_UNIT_TEST_FRAMEWORK_LIBRARY}"
+                                            "${arg_LINK_LIBRARIES}")
+
+  add_target_compile_options_private(TARGETS "${list_of_targets}"
+                                     COMPILE_OPTIONS "${arg_COMPILE_OPTIONS}")
+  
+endfunction()
+
+#
+# Private functions: Do not use directly
+######################################################################
+function(add_target_compile_options_private)
+  list(APPEND list_of_multivalue_keywords TARGETS COMPILE_OPTIONS)
+  cmake_parse_arguments("arg" "" "" "${list_of_multivalue_keywords}" "${ARGN}")
+  foreach( target IN LISTS arg_TARGETS)
+    target_compile_options(${target}
+                           PRIVATE
+                             ${arg_COMPILE_OPTIONS})
+  endforeach()
+endfunction()
+
+
+function(add_target_includes_private)
+
+  list(APPEND multi_value_keywords TARGETS LINK_LIBRARIES)
+  cmake_parse_arguments("arg" "" "" "${multi_value_keywords}" "${ARGN}")
+  foreach(target_name IN LISTS arg_TARGETS)
+    target_include_directories("${target_name}"
+                               PRIVATE
+                               "${arg_LINK_LIBRARIES}")
+  endforeach()
+endfunction()
+
+######################################
+function(add_target_link_libraries_private)
+  list(APPEND multi_value_keywords TARGETS LINK_LIBRARIES)
+  cmake_parse_arguments("arg" "" "" "${multi_value_keywords}" "${ARGN}")
+  foreach(target_name IN LISTS arg_TARGETS)
+    target_link_libraries("${target_name}"
+                               PRIVATE
+                               "${arg_LINK_LIBRARIES}")
+  endforeach()
+endfunction()
+
+######################################
+function(register_exe)
+  list(APPEND single_value_keywords NAMESPACE WORKING_DIRECTORY)
+  list(APPEND multi_value_keywords SOURCES)
+  
+  cmake_parse_arguments("arg" "" "${single_value_keywords}" 
+                         "${multi_value_keywords}" "${ARGN}")
+  foreach(source_name IN LISTS arg_SOURCES)
+    get_filename_component(target_name ${source_name} NAME_WE)
+    add_executable(${target_name} ${source_name})
+    # Fixme: The thing below doesnt work for some reason
+    #add_test(NAME ${test_namespace}.${target_name} 
+    #        COMMAND ${target_name} 
+    #        WORKING_DIRECTORY ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/tests)
+    #        
+    add_test(NAME
+               ${arg_NAMESPACE}.${target_name}
+             COMMAND
+               ${target_name}
+             WORKING_DIRECTORY
+               ${arg_WORKING_DIRECTORY})
+  endforeach()
+endfunction()
+
+######################################
+function(get_test_targets list_of_targets list_of_source_files )
+  foreach(source_name IN LISTS list_of_source_files)
+    get_filename_component(target_name ${source_name} NAME_WE)
+    list(APPEND list_of_targets_ ${target_name})
+  endforeach()
+  set(${list_of_targets} ${list_of_targets_} PARENT_SCOPE)
+endfunction()
+######################################################################
+
+# <<< former cmake "module" registerTests ends here <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
+
+
 
 aux_source_directory(
     ${CMAKE_CURRENT_LIST_DIR}