macro(check var val)
  if(NOT "${${var}}" STREQUAL "${val}")
    message(SEND_ERROR "${var} is \"${${var}}\", not \"${val}\"")
  endif()
endmacro()

message(STATUS "config=[${config}]")
check(test_0 "")
check(test_1 "content")
check(test_and_0 "0")
check(test_and_0_0 "0")
check(test_and_0_1 "0")
check(test_and_1 "1")
check(test_and_1_0 "0")
check(test_and_1_1 "1")
check(test_config_0 "0")
check(test_config_1 "1")
check(test_not_0 "1")
check(test_not_1 "0")
check(test_or_0 "0")
check(test_or_0_0 "0")
check(test_or_0_1 "1")
check(test_or_1 "1")
check(test_or_1_0 "1")
check(test_or_1_1 "1")