example:

tw-mbp-yic pants (master)]$ ./pants test examples/tests/python/example_test/hello/greet

...
11:27:13 00:01     [pytest]
11:27:13 00:01       [run]
                     
11:27:13 00:01         [chroot]INFO] /Users/yic/workspace/pants_ij/build-support/pants_dev_deps.venv/bin/python2.7 /Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4 --resultlog=/var/folders/yt/pxdd3gp96530xh_116kskmkh0000gn/T/tmpWSdqDI --confcutdir /Users/yic/workspace/pants --color yes examples/tests/python/example_test/hello/greet/greet.py
============== test session starts ===============
                     platform darwin -- Python 2.7.10 -- py-1.4.31 -- pytest-2.6.4
                     plugins: timeout, cov
                     collecting 0 items
                     >>>> PDB set_trace (IO-capturing turned off) >>>>>
                     > /Users/yic/workspace/pants/examples/tests/python/example_test/hello/greet/greet.py(10)<module>()
                     -> import os
                     (Pdb) import sys  
(Pdb) import pprint
(Pdb) pprint.pprint(sys.path)
['/Users/yic/workspace/pants/examples/tests/python/example_test/hello/greet',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.bootstrap',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4',
                      '/Users/yic/workspace/pants/src/python',
                      '/Users/yic/workspace/pants',
                      '/opt/twitter_mde/package/python2.7/current/lib/python27.zip',
                      '/opt/twitter_mde/package/python2.7/current/lib/python2.7',
                      '/opt/twitter_mde/package/python2.7/current/lib/python2.7/plat-darwin',
                      '/opt/twitter_mde/package/python2.7/current/lib/python2.7/plat-mac',
                      '/opt/twitter_mde/package/python2.7/current/lib/python2.7/plat-mac/lib-scriptpackages',
                      '/opt/twitter_mde/package/python2.7/current/lib/python2.7/lib-tk',
                      '/opt/twitter_mde/package/python2.7/current/lib/python2.7/lib-old',
                      '/opt/twitter_mde/package/python2.7/current/lib/python2.7/lib-dynload',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/coverage-3.7.1-cp27-cp27m-macosx_10_10_x86_64.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/py-1.4.31-py2.py3-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/unittest2-1.1.0-py2.py3-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/traceback2-1.4.0-py2.py3-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/pytest-2.6.4-py2-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/linecache2-1.0.0-py2.py3-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/ansicolors-1.0.2-py2-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/argparse-1.4.0-py2.py3-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/pytest_timeout-0.5-py2.py3-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/cov_core-1.15.0-py2-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/six-1.10.0-py2.py3-none-any.whl',
                      '/Users/yic/workspace/pants/.pants.d/python-setup/chroots/24101dfe6db56d32e0ad933ba47345abd2ea3fd4/.deps/pytest_cov-1.8.1-py2-none-any.whl']
                     (Pdb)