I want to customize robot framework test report, in order to fit my need.
Where can I find the related python source that handle this feature?
Or I need to create a 3rd party library to handle this?
One method, kind of lame but workable, is to use the keyword, 'Set Test Message'.  This lets you put text into the test message column of the report.  Whenever the test passes, you will see the message.  If it fails, you see the normal failure message.  
It would be great to be able to dynamically insert a documentation line, though.  I'd love to be able to have the keyword, "Set Documentation Message" so that in the keyword logic I could set it, instead of copying a '[Documentation]   blah, blah, blah' onto every line that it applies to.
how to customize robot framework test reports