ModuleNotFoundError when using setup.py install version of package, but not locally-

Problem

python setup.py install installs a package I’m developing all fine, but when I try importing the package I get a "ModuleNotFoundError" saying that a local package could not be found. The package works when locally (when I cd to the directory and attempt importing it in the python interpreter from there).

Recreation:

C:.
│   setup.py
│
└───package
    │   __init__.py
    │
    └───networking
            hello.py
            __init__.py

setup.py

from setuptools import setup

setup(
    name="test_package",
    packages=["package"],
    version="0.0.1",
    description="Test",
)

package/networking/__init__.py

from package.networking.hello import Hello

package/networking/hello.py

class Hello:
    def __init__(self, name):
        self.name = name

    def hello(self):
        print("Hello", self.name)

The following code works when testing locally (meaning, you cd to the directory with the package, then enter python interpreter there and try), but not after I have installed the package with setup.py install:

> python setup.py install
> cd .. # Change directory so we don't import locally, but use the version installed with setup.py
> python
>>> from package.networking import Hello
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'package.networking'
>>>

In constrast, this works when I’m in the same directory as the package:

> python
>>> from package.networking import Hello
>>> Hello("Test").hello()
Hello Test

>Solution :

setup(
    name="test_package",
    packages=["package"],
    ...
)

Don’t you miss something?

packages=[
    'package',
    'package.networking'
],
package_dir={
    'package': 'package',
    'package.networking': 'package/networking',
},

This is an example: first list all the packages, and then associate them with the directories.

setup.py must know which modules are to build, which name to give them, and where to find them.

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