First draft of the script.

README.md

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+# add_target
+
+A CMake function to bundle all the calls to add_library, target_link_libraries, etc. into one command, hence reducing name duplication in CMake scripts.
+
+## Example
+
+```cmake
+include(add_target.cmake)
+
+add_target(foo
+	STATIC
+		bar.cpp
+		bar.h
+		/implementation//
+		detail/impl.cpp:header
+	INCLUDES
+		PUBLIC .
+		PRIVATE detail
+	DEPENDENCIES
+		PUBLIC Boost::boost
+)
+```
+
+The above call to `add_target` behaves as if the following script was executed.
+
+```cmake
+add_library(foo STATIC bar.cpp bar.h detail/impl.cpp)
+target_include_directories(foo PUBLIC . PRIVATE detail)
+target_link_libraries(foo PUBLIC Boost::boost)
+
+source_group(NAME implementation FILES detail/impl.cpp)
+set_source_files_properties(detail/impl.cpp PROPERTIES HEADER_FILE_ONLY ON)
+```
+
+## References
+
+```cmake
+add_target(<name>
+	STATIC|SHARED|EXECUTABLE|HEADER_ONLY
+		<group name or sources with options> ...
+	[INCLUDES
+		[PUBLIC|PRIVATE|INTERFACE] <folders> ...
+	]
+	[DEPENDENCIES
+		[PUBLIC|PRIVATE|INTERFACE] <targets or libs> ...
+	]
+	[OPTIONS
+		[PUBLIC|PRIVATE|INTERFACE] <flags> ...
+	]
+	[DEFINITIONS
+		[PUBLIC|PRIVATE|INTERFACE] <defines> ...
+	]
+	[BOOST_TEST
+		<sources> ...
+	]
+	[GOOGLE_TEST
+		<sources> ...
+	]
+)
+```
+
+If `STATIC`, call `add_library(name STATIC sources)`. If or `add_executable`
+

add_target.cmake

@@ -0,0 +1,179 @@
+cmake_minimum_required(VERSION 3.18)
+
+if (COMMAND add_target)
+	return()
+endif()
+
+function(add_target name)
+	if (TARGET ${name})
+		message(FATAL_ERROR "Cannot add target ${name} because it already exists.")
+	endif()
+
+	set(options "STATIC;SHARED;EXECUTALBE;HEADER_ONLY")
+	set(multivalue_keywords "INCLUDES;DEPENDENCIES;OPTIONS;DEFINITIONS;BOOST_TEST;GOOGLE_TEST")
+
+	cmake_parse_arguments(PARSE_ARGV 1 io1
+		"${options}"
+		""
+		"${multivalue_keywords}"
+	)
+
+
+	# options are mutually exclusive
+	# the found_options list must have length one
+	# at the end of this loop
+	foreach(opt IN LISTS options)
+		if (DEFINED io1_${opt})
+			list(APPEND found_option ${opt})
+		endif()
+	endforeach()
+	list(LENGTH found_option found_option_count)
+	if (found_option_count EQUAL 0)
+		message(FATAL_ERROR "add_target: missing target type.")
+	elseif (NOT found_option_count EQUAL 1)
+		message(FATAL_ERROR "add_target: cannot define multiple target types.")
+	endif()
+
+	# target sources are the leftover values
+	fetch_sources_and_groups("${io1_UNPARSED_ARGUMENTS})" source_list group_list all_sources)
+	apply_source_groups("${source_list}" "${group_list}")
+	apply_source_options("${all_sources}" sources)
+
+	# create the target with the type detected by found_option
+	if (DEFINED io1_STATIC)
+		add_library(${name} STATIC ${sources})
+	elseif(DEFINED io1_SHARED)
+		add_library(${name} SHARED ${sources})
+	elseif(DEFINED io1_EXECUTABLE)
+		add_executable(${name} ${sources})
+	elseif(DEFINED io1_HEADER_ONLY)
+		add_library(${name} INTERFACE ${sources})
+	endif()
+	message(STATUS "add_target: created ${found_option} target ${name}.")
+
+
+	# configure the target from the multi-value keywords
+	if (DEFINED io1_INCLUDES)
+		target_include_directories(${name} ${io1_INCLUDES})
+	endif()
+	if (DEFINED io1_DEPENDENCIES)
+		target_link_libraries(${name} ${io1_DEPENDENCIES})
+	endif()
+	if (DEFINED io1_OPTIONS)
+		target_compile_options(${name} ${io1_OPTIONS})
+	endif()
+	if(DEFINED io1_DEFINITIONS)
+		target_compile_definitions(${name} ${io1_DEFINITIONS})
+	endif()
+	if(DEFINED io1_BOOST_TEST AND BUILD_TESTING)
+		set(test_name "boost-test-${name}")
+		if (TARGET ${test_name})
+			message(FATAL_ERROR "add_target: cannot create boost test target ${test_name} because it already exists.")
+		else()
+			message(STATUS "add_target: created boost test target ${test_name}.")
+		endif()
+
+		find_package(Boost REQUIRED COMPONENTS unit_test_framework)
+		add_executable(${test_name} ${test_sources})
+		target_link_libraries(${test_name} PRIVATE ${name} Boost::unit_test_framework)
+
+		add_test(
+		    NAME ${test_name}
+		    COMMAND ${test_name} --catch_system_error=yes --detect_memory_leaks --logger=JUNIT,all,junit_${test_name}.xml
+		    WORKING_DIRECTORY $<TARGET_FILE_DIR:${test_name}>)
+
+	endif()
+	if(DEFINED io1_GOOGLE_TEST AND BUILD_TESTING)
+		if (NOT COMMAND gtest_discover_tests)
+			include(GoogleTest)
+		endif()
+
+		set(test_name "google-test-${name}")
+		if (TARGET ${test_name})
+			message(FATAL_ERROR "add_target: cannot create google test target ${test_name} because it already exists.")
+		else()
+			message(STATUS "add_target: created google test target ${test_name}.")
+		endif()
+
+		find_package(GTest REQUIRED)
+		add_executable(${test_name} ${test_sources})
+		target_link_libraries(${test_name} PRIVATE ${name} GTest::Main)
+
+		gtest_discover_tests(${test_name}
+			WORKING_DIRECTORY $<TARGET_FILE_DIR:${test_name}>
+		)
+	endif()
+
+endfunction()
+
+function(fetch_sources_and_groups files source_list group_list all_sources)
+	set(current_group_name ".")
+	set(current_group_path "/.")
+
+	unset(${source_list})
+	unset(${group_list})
+	unset(${all_sources})
+
+	foreach(file IN LISTS files)
+		if ("${file}" MATCHES "^(.*)//$")
+			set(new_group_path "${CMAKE_MATCH_1}")
+
+			if (IS_ABSOLUTE "${new_group_path}")
+				set(current_group_path "${new_group_path}")
+			else()
+				get_filename_component(current_group_path "${new_group_path}" ABSOLUTE BASE_DIR "${current_group_path}")
+			endif()
+
+			string(SUBSTRING "${current_group_path}" 1 -1 current_group_name)
+
+		else()
+			if (NOT "${current_group_name}" STREQUAL ".")
+				list(APPEND temp_group_list "${current_group_name}")
+				list(APPEND temp_source_list "${file}")
+			endif()
+			list(APPEND temp_all_sources "${file}")
+		endif()
+	endforeach()
+
+	set(${all_sources} "${temp_all_sources}" PARENT_SCOPE)
+	set(${source_list} "${temp_source_list}" PARENT_SCOPE)
+	set(${group_list} "${temp_group_list}" PARENT_SCOPE)
+endfunction()
+
+# parse file.c[:opt1,opt2,opt3,...]
+function(parse_file_options str file options)
+	if ("${str}" MATCHES "^(.*):(.*)$")
+		set(${file} "${CMAKE_MATCH_1}" PARENT_SCOPE)
+		string(REPLACE "," ";" temp "${CMAKE_MATCH_2}") # it does not work with ${options} instead of temp, no clue why
+		set(${options} "${temp}" PARENT_SCOPE)
+	else()
+		set(${file} "${str}" PARENT_SCOPE)
+		unset(${options} PARENT_SCOPE)
+	endif()
+endfunction()
+
+function(apply_source_options files sources)
+	foreach(file IN LISTS files)
+		parse_file_options("${file}" f opt)
+		apply_file_options("${f}" "${opt}")
+	endforeach()
+endfunction()
+
+# apply the provided group to each file
+# asserts that files and groups have the same size.
+function(apply_source_groups files groups)
+	foreach(file group IN ZIP_LISTS files groups)
+		source_group(NAME ${group} FILES ${file})
+	endforeach()
+endfunction()
+
+# apply options provided as file.c:opt1,opt2,opt3,... if any
+function(apply_file_options file options)
+	cmake_parse_arguments(io1 "cpp;header" "" "" ${options})
+	if (DEFINED io1_cpp)
+		set_source_files_properties("${file}" PROPERTIES LANGUAGE CXX)
+	endif()
+	if (DEFINED io1_header)
+		set_source_files_properties("${file}" PROPERTIES HEADER_FILE_ONLY ON)
+	endif()
+endfunction()