setting breakpoints with nosetests --pdb option

nosetests --pdb let's me halt upon error or failure, but this is too late for my needs. Stepping through code during execution helps me debug where the problem is.

However, nosetests are helpful as they allow tests that rely on relative imports (i.e. tests in a package).

How can I set breakpoints before the tests are executed? Currently I'm using:

python -m pdb /path/to/my/nosetests testfile.py

This solution isn't adequate. Nosetests interfere with pdb output, and my keyboard controls (e.g. arrow keys) are broken.

Using import pdb; pdb.set_trace() would seem like a good idea, however nosetests is blocking my access to the pdb console.

Even better than remembering to use -s is to use the set_trace variant that comes with Nose. Add

from nose.tools import set_trace; set_trace()

wherever you'd like to break in to the debugger. The stdin/out redirection will be taken care of for you. The only strange side effect I've run into is the inability to restart your code from within pdb (using run) while debugging during a nose run.

You can add

import pdb; pdb.set_trace() 

anywhere in your source that you want to stop in the debugger.

Make sure you pass -s to nose so that it does not capture stdout.

If you have ipython, for unlimited awesomeness use:

import ipdb; ipdb.set_trace() 

*unlimited awesomeness: just like ipython - auto-completion, coloring etc.

If you are using pytest, you can use

import pytest; pytest.set_trace()

See documentation.