Buildbot and nose test coverage

I have been using buildbot (and nose) for a little while now and I really like it (I like nose too, just for the record). It's very hackable and I think I will be able to accomplish most, if not all, of the things I want to do with it. One of those things is to get the test coverage displayed and easily accessible from buildbot's web status application. Like so:

Can you see the little link with the text "coverage 84%"? Clicking that link will take you to the nice HTML report generated by nose (via coverage.py) during the test run.

To use this little hack you will need a buildbot slave with access to a directory that gets published by some web server. The custom build step below puts the coverage report directly into that directory and then adds an URL to the report, that will be visible in buildbot, with a call to addURL().

import re
from buildbot.process.properties import WithProperties
from buildbot.steps.shell import ShellCommand

class Nose(ShellCommand):
    def __init__(self):
        self.coverage_path = '/var/www/foo/coverage-%s'
        self.coverage_url = 'http://example.com/foo/coverage-%s'
        d = WithProperties('--cover-html-dir=' + self.coverage_path, 
                           'buildnumber')
        command = ['nosetests', '--with-coverage', '--cover-erase', 
                   '--cover-html', d]
        ShellCommand.__init__(self, command=command)
    
    def describe(self, done=False):
        if not done:
            return 'testing'
        else:
            return 'test done'

    def createSummary(self, log):
        buildnumber = self.getProperty('buildnumber')
        coverage_index = (self.coverage_path + '/index.html') % buildnumber
        f = open(coverage_index)
        m = re.search(r'Percent: (\d+) %', f.read())
        f.close()
        self.addURL("coverage %s%%" % m.group(1), 
                    self.coverage_url % buildnumber)

Good enough for now.

An even nicer version of this build step would download all the coverage report files from the slave to the master. The master would then serve the files using it's web status application. This would eliminate the need for a web server on the slave. But that's the deluxe version, more on that later.