Looks like a badly built package (assuming that json is installed on the user's system when it is actually outside the standard library).

You can use pip to globally install json: just write pip install json. You may need to install pip separately.

The error occurred because you have installed your dependencies using Sudo. This has installed your pip dependencies only for Sudo users, whilst you are running your Django application as a non-sudo user. This is the reason why you didn't saw your packages when you did pip freeze but you saw them after doing sudo pip3 freeze

To solve this

1. Install python3-venv with this command sudo apt-get install python3-venv
2. Create a virtual environment python3 -m venv env this command will create a virtual environment named env
3. Activate the virtual environment with this command source env/bin/activate

Once you have done this you will see a (env) before your shell which indicates that your virtual environment is activated now need to install the dependencies inside this

1. cd to your requirements.txt and type pip3 install -r requirements.txt make sure you do it without sudo (because you will run your Django app in your web server as a non-sudo privilege user for security reasons)

After this, you can run your Django app with your virtual environment kept active.

Note: I do not have a definitive answer but will offer a series of steps you can try:

The first thing is see if you can import json from the usual python interpreter:

import json
print(json.__file__) #this would be important to know if it works

If that does work (as well as commenting what json.__file__ is) you would then want to try to use pip from the interpreter.

If you can't import json normally:

This is not surprising, I did not expect pip to be looking in a non-standard place for modules. You will want to figure out where the json package should be located on your computer, you can do this by importing another module from the standard library and looking at it's __file__:

>>> import fractions
>>> fractions.__file__
'/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/fractions.py'

This will obviously be different for you but I'd expect there to be a json folder in the same folder as fractions.py

if you can't import fractions or queue or datetime etc.

If you can't import anything from the standard library you will probably want to just reinstall python.

If the json folder is there and contains an __init__.py

Use the rename function of your file browser to make sure there are no weird special characters, but other then that I'm not sure, if you can import fractions.py but not a package from the same folder that would imply there is something very wrong with the import mechanics of your python version.

If the json folder is not with the rest of the standard library

It is possible that your python distribution has a different structure then I'd expect, it at least can't hurt to take a look for it.

You can search for the json folder amongst your various python files using the find command, not really sure how it works but just another thing to try. If you do find it with the __init__.py, encode.py, decode.py, scanner.py, and tool.py (at least those are the ones in my version) you'll probably want to figure out how it got there, but maybe just move it to the same folder as the rest of the standard library.

If you can't find the json package or you find it and it is corrupted

Well then you will need to replace it! Don't worry, this isn't too hard, just grab a source release of python from the site and extract the json package from it, once it is uncompressed the json folder should be in the Lib folder. Simply copy/move it to the rest of the standard library and you should be good to go!

I hope this helps you debug what is going on, This covers all the scenarios I could imagine happening and I would be interested in which one fixed your issue (or what you were able to figure out so I can come up with more options)

You should specify the full path to the module, including the package names, when you use patch. Also, do not use parentheses in the path. Modify the return_value attribute of the Mock object to customize the returning value of a call to the object:

with patch('projectxapp.billing.Billing.create_invoice_pdf') as p1:
    p1.return_value = '/invoice.pdf'
    test = billing.Billing().send_invoices(invoices)