ModuleNotFoundError on console_scripts execution

Question

What is happening

I have a simple CLI project written in Python 3 (Python 3.6.0 interpreter) which I can run using the package and module name directly from the command line, but which fails when installed with setuptools:

# success
❯ python -m myProject.cli --version
0.0.1.dev0

# failure
❯ mycli --version
Traceback (most recent call last):
  File "/path/myProject/venv/bin/mycli", line 11, in <module>
    load_entry_point('myProject==0.0.1.dev0', 'console_scripts', 'mycli')()
  File "/path/myProject/venv/lib/python3.6/site-packages/pkg_resources/__init__.py", line 560, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/path/myProject/venv/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2648, in load_entry_point
    return ep.load()
  File "/path/myProject/venv/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2302, in load
    return self.resolve()
  File "/path/myProject/venv/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2308, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
ModuleNotFoundError: No module named 'myProject'

Project setup

The project has the following structure:

.
├── myProject
│   └── cli.py
└── setup.py

I'm expecting the script to be installed as mycli later on, therefore my setup.py look like this:

from setuptools import setup, find_packages

from myProject.cli import __version__

setup(

    # Package info
    name = 'myProject',
    version = __version__,
    packages = find_packages(),

    # Dependencies
    install_requires = [
        'docopt>=0.6.2'
    ],

    # Script info
    entry_points = {
        'console_scripts': [
            'mycli = myProject.cli:main'
        ]
    }
)

Installation

The installation completes without error:

❯ python setup.py install
running install
running bdist_egg
running egg_info
writing myProject.egg-info/PKG-INFO
writing dependency_links to myProject.egg-info/dependency_links.txt
writing entry points to myProject.egg-info/entry_points.txt
writing requirements to myProject.egg-info/requires.txt
writing top-level names to myProject.egg-info/top_level.txt
reading manifest file 'myProject.egg-info/SOURCES.txt'
writing manifest file 'myProject.egg-info/SOURCES.txt'
installing library code to build/bdist.macosx-10.12-x86_64/egg
running install_lib
warning: install_lib: 'build/lib' does not exist -- no Python modules to install

creating build/bdist.macosx-10.12-x86_64/egg
creating build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/PKG-INFO -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/SOURCES.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/dependency_links.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/entry_points.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/requires.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/top_level.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
zip_safe flag not set; analyzing archive contents...
creating 'dist/myProject-0.0.1.dev0-py3.6.egg' and adding 'build/bdist.macosx-10.12-x86_64/egg' to it
removing 'build/bdist.macosx-10.12-x86_64/egg' (and everything under it)
Processing myProject-0.0.1.dev0-py3.6.egg
Removing /path/myProject/venv/lib/python3.6/site-packages/myProject-0.0.1.dev0-py3.6.egg
Copying myProject-0.0.1.dev0-py3.6.egg to /path/myProject/venv/lib/python3.6/site-packages
myProject 0.0.1.dev0 is already the active version in easy-install.pth
Installing mycli script to /path/myProject/venv/bin

Installed /path/myProject/venv/lib/python3.6/site-packages/myProject-0.0.1.dev0-py3.6.egg
Processing dependencies for myProject==0.0.1.dev0
Searching for docopt==0.6.2
Best match: docopt 0.6.2
Adding docopt 0.6.2 to easy-install.pth file

Using /path/myProject/venv/lib/python3.6/site-packages
Finished processing dependencies for myProject==0.0.1.dev0

pip show shows me the expected result as well:

❯ pip show myProject
Name: myProject
Version: 0.0.1.dev0
Location: /path/myProject/venv/lib/python3.6/site-packages/myProject-0.0.1.dev0-py3.6.egg
Requires: docopt

Nevertheless the ModuleNotFoundError: No module named 'myProject' error always pops up when I execute mycli.

I'd be very grateful for any pointer.

Answer 1

I found the solution to my issue, which I believe was a misunderstanding of PEP 420 -- Implicit Namespace Packages.

This page states that, since Python 3.3:

While looking for a module or package named "foo", for each directory in the parent path:

• If <directory>/foo/__init__.py is found, a regular package is imported and returned.
• If not, but <directory>/foo is found and is a directory, it is recorded and the scan continues with the next directory in the parent path.

If the scan completes without returning a module or package, and at least one directory was recorded, then a namespace package is created. The new namespace package:

• Has a __path__ attribute set to an iterable of the path strings that were found and recorded during the scan.
• Does not have a __file__ attribute.

As defined in the pkg_resources documentation:

A namespace package is a package that only contains other packages and modules, with no direct contents of its own.

My package, as I described it, fell into that category, which was not intended.

After adding an empty __init.py__ below the myProject/ directory I see this happening during the install step:

❯ python setup.py build    
running build
running build_py
creating build/lib
creating build/lib/myProject
copying myProject/__init__.py -> build/lib/myProject
copying myProject/cli.py -> build/lib/myProject

Before:

>>> myProject.__path__
_NamespacePath(['/path/myProject'])
>>> myProject.__file__
AttributeError: module 'myProject' has no attribute '__file__'

After:

>>> myProject.__path__
['/path/myProject']
>>> myProject.__file__
'/path/myProject/__init__.py'