Uncaught ZeroDivisionError when generating XML report

[nedbat]

Originally reported by Chris Rebert (Bitbucket: cvrebert, GitHub: cvrebert)

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If you ask coverage v3.6 to generate an XML report under a no-meaningful-tests edge case, it crashes:

<nose portion of call stack elided>
  File "/var/lib/jenkins/shiningpanda/jobs/f9dc77ce/virtualenvs/d41d8cd9/lib/python2.7/site-packages/coverage/control.py", line 647, in xml_report
    return reporter.report(morfs, outfile=outfile)
  File "/var/lib/jenkins/shiningpanda/jobs/f9dc77ce/virtualenvs/d41d8cd9/lib/python2.7/site-packages/coverage/xmlreport.py", line 88, in report
    return 100.0 * (lhits_tot + bhits_tot) / (lnum_tot + bnum_tot)
ZeroDivisionError: float division by zero

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• Bitbucket: https://bitbucket.org/ned/coveragepy/issue/250

[nedbat]

@cvrebert I thought I understood what this report meant, but I can't reproduce it now. Can you give me more details? What does a "no-meaningful-tests edge case" mean? How are you running your tests, and your XML report?

[nedbat]

Original comment by Chris Rebert (Bitbucket: cvrebert, GitHub: cvrebert)

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Sorry. Here's a more detailed testcase description:

1. Create this directory+file structure:

/foo/
/foo/bar/
/foo/bar/__init__.py       [empty file]
/foo/bar/test_foobar.py    [content given below]

#!python

# /foo/bar/test_foobar.py
from unittest import TestCase

class MyTestCase(TestCase):
    pass

2. Create a new Python 2.7 virtualenv, and activate it.
3. Run pip install coverage nose
4. With /foo/ as your working directory, run nosetests --with-xunit --with-coverage --cover-package=bar --cover-xml
5. Observe that the command crashed with a traceback, due to a ZeroDivisionError in coverage.

[nedbat]

Fixed in 129c86f0e044a96a (bb)