Repository: PlasmaPy/PlasmaPy

Issue:
ModuleNotFoundError: No module named 'plasmapy.classes' on plasmapy import
On importing freshly installed plasmapy into a new environment:

    (plasmapy) [~]$ python
    Python 3.6.2 |Continuum Analytics, Inc.| (default, Jul 20 2017, 13:51:32) 
    [GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import plasmapy
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/home/dominik/.anaconda3/envs/plasmapy/lib/python3.6/site-packages/plasmapy/__init__.py", line 8, in <module>
        from .classes import Plasma
    ModuleNotFoundError: No module named 'plasmapy.classes'

The goal of this one is being able to import plasmapy. At all.

The issue likely lies in `plasmapy/__init__.py`. 

To quote @cadair 's words of encouragement on this bugfixing journey, *packaging is a special kind of hell*. 


Discussion:
Did this get fixed? I tried to recreate the problem and everything seemed to work for me.

```
haggerty@Colbylpt:~/Programing/PlasmaPy:master> source activate plasmapy
(plasmapy)  haggerty@Colbylpt:~/Programing/PlasmaPy:master> pip install .
Processing /Users/haggerty/Programing/PlasmaPy
Collecting numpy (from plasmapy==0.1.dev1)
  Using cached numpy-1.13.1-cp36-cp36m-macosx_10_6_intel.macosx_10_9_intel.macosx_10_9_x86_64.macosx_10_10_intel.macosx_10_10_x86_64.whl
Collecting scipy (from plasmapy==0.1.dev1)
  Using cached scipy-0.19.1-cp36-cp36m-macosx_10_6_intel.macosx_10_9_intel.macosx_10_9_x86_64.macosx_10_10_intel.macosx_10_10_x86_64.whl
Collecting astropy (from plasmapy==0.1.dev1)
  Downloading astropy-2.0.2-cp36-cp36m-macosx_10_6_intel.macosx_10_9_intel.macosx_10_9_x86_64.macosx_10_10_intel.macosx_10_10_x86_64.whl (7.6MB)
    100% |████████████████████████████████| 7.6MB 88kB/s
Collecting coveralls (from plasmapy==0.1.dev1)
  Using cached coveralls-1.2.0-py2.py3-none-any.whl
Collecting pytest>=2.8 (from astropy->plasmapy==0.1.dev1)
  Using cached pytest-3.2.2-py2.py3-none-any.whl
Collecting docopt>=0.6.1 (from coveralls->plasmapy==0.1.dev1)
Collecting requests>=1.0.0 (from coveralls->plasmapy==0.1.dev1)
  Using cached requests-2.18.4-py2.py3-none-any.whl
Collecting coverage>=3.6 (from coveralls->plasmapy==0.1.dev1)
  Using cached coverage-4.4.1-cp36-cp36m-macosx_10_10_x86_64.whl
Requirement already satisfied: setuptools in /Users/haggerty/anaconda/envs/plasmapy/lib/python3.6/site-packages (from pytest>=2.8->astropy->plasmapy==0.1.dev1)
Collecting py>=1.4.33 (from pytest>=2.8->astropy->plasmapy==0.1.dev1)
  Using cached py-1.4.34-py2.py3-none-any.whl
Collecting idna<2.7,>=2.5 (from requests>=1.0.0->coveralls->plasmapy==0.1.dev1)
  Using cached idna-2.6-py2.py3-none-any.whl
Collecting urllib3<1.23,>=1.21.1 (from requests>=1.0.0->coveralls->plasmapy==0.1.dev1)
  Using cached urllib3-1.22-py2.py3-none-any.whl
Collecting chardet<3.1.0,>=3.0.2 (from requests>=1.0.0->coveralls->plasmapy==0.1.dev1)
  Using cached chardet-3.0.4-py2.py3-none-any.whl
Collecting certifi>=2017.4.17 (from requests>=1.0.0->coveralls->plasmapy==0.1.dev1)
  Using cached certifi-2017.7.27.1-py2.py3-none-any.whl
Installing collected packages: numpy, scipy, py, pytest, astropy, docopt, idna, urllib3, chardet, certifi, requests, coverage, coveralls, plasmapy
  Found existing installation: certifi 2016.2.28
    Uninstalling certifi-2016.2.28:
      Successfully uninstalled certifi-2016.2.28
  Running setup.py install for plasmapy ... done
Successfully installed astropy-2.0.2 certifi-2017.7.27.1 chardet-3.0.4 coverage-4.4.1 coveralls-1.2.0 docopt-0.6.2 idna-2.6 numpy-1.13.1 plasmapy-0.1.dev1 py-1.4.34 pytest-3.2.2 requests-2.18.4 scipy-0.19.1 urllib3-1.22
```
The install looks good to me.

```
(plasmapy)  haggerty@Colbylpt:~/Programing/PlasmaPy:master> python
Python 3.6.2 |Continuum Analytics, Inc.| (default, Jul 20 2017, 13:14:59)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import plasmapy
>>>
```

And no errors on the import.

Are you still getting this @StanczakDominik ?
Yeah, just confirmed as still happening on two separate machines. Weird... :confused: 
Is your branch up to date? I started working on this issue because I had this exact same problem a few weeks back, so I figured I would try to fix it, but now I am not getting it any more.
What do you mean by branch here? I'm running this in a completely clean conda env on a laptop that hasn't had anything to do with PlasmaPy, so nothing I did on any of my git branches should be of any importance, right?
Sorry I meant, is whatever current branch on your local repository up-to-date with the plasmapy master branch on github?

Where did you grab plasmapy from? plasmapy/plasmapy/master or something like StanczakDominik/PlasmaPy/particle_step ?
It is, but that's irrelevant to the laptop. @SolarDrew says on Matrix he's got the same issue going on, so maybe something's weird with your config? You're outnumbered 2:1 right now :D
I can also confirm this bug.
![screenshot](https://user-images.githubusercontent.com/11430843/30931852-278c0724-a3c6-11e7-9a8d-75fa5f8196df.png)


Resolving patch:
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,4 @@
-from setuptools import setup
+from setuptools import setup, find_packages
 
 
 # Package metadata
@@ -32,7 +32,7 @@
         'Topic :: Scientific/Engineering :: Astronomy',
         'Development Status :: 2 - Pre-Alpha',
         ],
-      packages=["plasmapy"],
+      packages=find_packages(),
       zip_safe=False,
       use_2to3=False,
       python_requires='>=3.6',


Test patch: