# https://cmake.org/pipermail/cmake/2009-July/030788.html
#-------------------------------------------------
# some argument checking:
# test_cmd is the command to run with all its arguments
if( NOT test_cmd )
   message( FATAL_ERROR "Variable test_cmd not defined" )
endif( NOT test_cmd )

# output_blessed contains the name of the "blessed" output file
if( NOT output_blessed )
   message( FATAL_ERROR "Variable output_blessed not defined" )
endif( NOT output_blessed )

# output_test contains the name of the output file the test_cmd will produce
if( NOT output_test )
   message( FATAL_ERROR "Variable output_test not defined" )
endif( NOT output_test )

# convert the space-separated string to a list
separate_arguments( test_args )
message( "ARGUMENTS: ${test_cmd} ${test_args}" )

execute_process(
   COMMAND ${test_cmd} ${test_args} 
   OUTPUT_FILE ${output_test}
)

execute_process(
   COMMAND ${CMAKE_COMMAND} -E compare_files ${output_blessed} ${output_test}
   RESULT_VARIABLE test_not_successful
)

if( test_not_successful )
   message( SEND_ERROR "${output_test} does not match ${output_blessed}!" )
endif( test_not_successful )
#-------------------------------------------------