ant: create dirset with all dirs containing files in a fileset - unit-testing

Question

Context: a directory, recursively containing python unittest.TestCases:
projectdir/build.xml
projectdir/src/x.java
projectdir/distribute/p.jar
projectdir/tests/a/test1.py
projectdir/tests/a/test2.py
projectdir/tests/b/test1.py
projectdir/tests/c/test1.py
projectdir/tests/javaunittests/test2.java
And I want ant to call
python -m unittest discover -s a b c
Now I was trying to convert a fileset to the dirset of the containing directories? The idea is to run python unittests:
<apply command="python">
<arg line="-m unittest"/>
<arg value="-s"/>
<dirset include="${python_unittests}"/>
</apply>
where ${python_unittests}" would refer to afileset` (but I don't find how) like this:
<fileset id="python_unittests" include="**/*.py">
<containsregexp expression="\(unittest.TestCase\)"/>
</fileset>
Or am I erring, and is there a better way to achieve this?

Answer 1

You want all python files with testcases, you don't need a dirset, use :
<apply executable="python">
<arg line="-m unittest"/>
<arg value="-s"/>
<fileset dir="projectdir" includes="**/*.py">
<contains text="unittest.TestCase"/>
</fileset>
</apply>
EDIT
Just checked the docs for unittest on python.org after your comment.
As i understand it, that should be sufficient :
<property name="projectroot" location="foo/bar/yourprojectdir"/>
<exec executable="python" failonerror="true">
<arg line="-m unittest discover ${projectroot} 'test*.py'"/>
</exec>
as python docs section 26.3.3. Test Discovery explains :
The -s, -p, and -t options can be passed in as positional arguments in that order. The following two command lines are equivalent:
python -m unittest discover -s project_directory -p '*_test.py'<br>
python -m unittest discover project_directory '*_test.py'
I expect that discover works recursively starting from project_directory.