<p>Does Ruby have any tools along the lines of <a href="http://pypi.python.org/pypi/pylint" rel="noreferrer">pylint</a> for analyzing source code for errors and simple coding standards?</p>

<p>It would be nice if it could be integrated with <a href="http://cruisecontrolrb.thoughtworks.com/" rel="noreferrer">cruisecontrolrb</a> for continuous integration.</p>

<p>Or does everyone write such good tests that they don't need source code checkers!</p>

One recently-updated interesting-looking tool is
Ruby Object Oriented Design Inferometer
- roodi for short. It's at v1.3.0, so I'm guessing it's fairly mature.
I haven't tried it myself, because my code is of course already beyond reproach (hah).
As for test coverage (oh dear, I haven't tried this one either) there's
rcov
Also (look, I am definitely going to try some of these today. One at least) you might care to take a look at
flog and flay
for another style checker and a refactoring candidate finder.