First steps with dialyzer

Today I tried to use dialyzer on my s_server module.  Don't  worry if you have not read any of my posts about this module, it doesn't do any thing useful !

At first I tried to analyse my test module:

philip@desktop:s_server/src$ erlc +debug_info s_server_tests.erl

philip@desktop:s_server/src$ dialyzer -c s_server_tests.erl --build_plt

Which gave me this result:

dialyzer: {dialyzer_error,"Byte code compiled with debug_info is needed to build the PLT"}
[{dialyzer_options,check_output_plt,1,
                   [{file,"dialyzer_options.erl"},{line,86}]},
 {dialyzer_options,postprocess_opts,1,
                   [{file,"dialyzer_options.erl"},{line,75}]},
 {dialyzer_options,build,1,[{file,"dialyzer_options.erl"},{line,63}]},
 {dialyzer_cl_parse,cl,1,[{file,"dialyzer_cl_parse.erl"},{line,218}]},
 {dialyzer_cl_parse,start,0,[{file,"dialyzer_cl_parse.erl"},{line,46}]},
 {dialyzer,plain_cl,0,[{file,"dialyzer.erl"},{line,60}]},
 {init,start_it,1,[]},
 {init,start_em,1,[]}]

The problem actually was that I should have given the beam files to dialyzer to analyse e.g.

philip@desktop:s_server/src$ dialyzer -c s_server_tests.beam --build_plt
  Creating PLT /home/philip/.dialyzer_plt ...
Unknown functions:
  eunit:test/1
  s_server:ping/0
  s_server:start_link/0
  s_server:stop/0
 done in 0m0.40s
done (passed successfully)