I’ve been spending a lot of time lately trying to get the workflow between Trac and TestLink to make sense. I’m far from having the perfect solution, but a great first step was creating a Trac wiki macro that will link to specific test cases in TestLink. There’s lots of areas in which this could be improved in the future…

Create this as conf/TestLinkMacro.py in your project (replacing test.example.com with your TestLink host):

import re

from trac.wiki.macros import WikiMacroBase

class TestLinkMacro(WikiMacroBase):
    """Macro to generate automatic links to test cases in TestLink.
    """

    def expand_macro(self, formatter, name, args):
        """Expand a TestLink test case ID into a link
        """
        TestLinkServer = 'test.example.com'
        matches = re.match(r'(.*)-(d+)$', args)
        
        return '<a href="https://' + TestLinkServer + '/linkto.php?tprojectPrefix=' + matches.group(1) + '&item=testcase&id=' + matches.group(0) + '">[[TestLink(' + matches.group(0) + ')]]</a>'

After putting this in place, and possibly restarting Trac, you can create a direct link to test case m3-123 in a wiki by typing [[TestLink(m3-123)]]. Note that I could have changed the actual string displayed in the wiki to anything I wanted, but I chose to leave it looking identical to the actual macro (but linked) so that it would reinforce to people the correct format for the test case links.

This macro is useful in several ways, but the most obvious is allowing us to enter regression test case IDs into commit messages (which then get associated with a ticket in Trac and are displayed with the wiki engine, making the test case link clickable).
With commit messages being associated with tickets automatically and being displayed by the wiki engine, this gives us a nice syntax to enter regression case links into commit messages and be very followable later

Edit 2011-09-13:

See also this update to my use of macros for linking to test cases and this comment on custom ticket field wiki parsing, both of which have a direct relation to this post