Py.test test class failing due to import error

Question

I have a tests/ directory with a single file that imports a number of 3rd party programs (pandas, etc). I'm running within a virtual env that has pandas installed.

pip freeze | grep pandas; cat requirements.txt | grep pandas
pandas==0.16.0
pandas==0.16.0

When I execute py.test I get the following error:

tests/test_pipeline.py:4: in <module>
    import pandas as pd
E   ImportError: No module named pandas

Which is the import pandas call within the test_pipeline.py file.

cat -n  tests/test_pipeline.py  | more
     1  import sys
     2  import os
     3  import filecmp
     4  import pandas as pd

Why is this an error when virtualenv is setup correctly? What am I doing incorrectly?

TIA

Answer 1

Do you have multiple Python versions installed? If so, py.test may be using a different version as the version which is used when running a script from the command line.

Eg. on my system, I have Python 3.5 on my PATH , so:

>py.test --version
This is pytest version 2.8.1, imported from c:\program files\python 3.5\lib\site-packages\pytest.py

But if I run a python script from the command line: (this one prints platform.python_version() )

>test.py
2.7.8

In fact, that version depends on what version I declare in my script, eg. if the first line of that script reads #! python3 #! python3 , it will print 3.5.0 instead. (and Linux systems also look at that shebang line)

So make sure pandas is installed on the version you use when you run py.test.