= create a test file =

Choose a name for your test file. We'll use {{{test_fname.py}}}:

{{{
touch src/allmydata/test/test_fname.py
}}}

{{{
./bin/tahoe debug trial allmydata.test.test_fname
}}}

Okay, so it didn't work, because there is no file by that name. Create such a file, with these contents:

{{{
rom twisted.trial import unittest

class T(unittest.TestCase):
    def test_a(self):
        pass
}}}

Now install Ned Batchelder's "[http://nedbatchelder.com/code/coverage/ coverage"] tool and run your with code coverage, like this:

{{{
./bin/tahoe @coverage run --branch --include='src/allmydata/*' @tahoe debug trial allmydata.test.test_fname
}}}

If you installed coverage from Debian or Ubuntu then you have to name it {{{python-coverage}}}, like this:

{{{
./bin/tahoe @python-coverage run --branch --include='src/allmydata/*' @tahoe debug trial allmydata.test.test_fname
}}}

This does the same as running the tests without coverage -- print a list of what happened when each test was run. It also writes out a file named {{{.coverage}}} into the current directory. Run the following command to read that file and produce nice HTML pages:

{{{
./bin/tahoe @coverage html
}}}

That will product a directory named {{{htmlcov}}}. View its contents with a web browser.