ModuleNotFoundError with pytest

Question

I want my tests folder separate to my application code. My project structure is like so

myproject/
  myproject/
    myproject.py
    moduleone.py
  tests/
    myproject_test.py

myproject.py

from moduleone import ModuleOne

class MyProject(object)
....

myproject_test.py

from myproject.myproject import MyProject
import pytest

...

I use myproject.myproject since I use the command

python -m pytest

from the project root directory ./myproject/

However, then the imports within those modules fail with

E ModuleNotFoundError: No module named 'moduleone'

I am running Python 3.7 and have read that since 3.3, empty __init__ files are no longer needed which means my project becomes an implicit namespace package

However, I have tried adding an __init__.py file in myproject/myproject/ and also tried adding a conftest.py file in myproject/ but neither works

I have read answers that say to mess with the paths and then upvoted comments in other questions saying not to.

What is the correct way and what am I missing?

EDIT;

Possibly related, I used a requirements.txt to install pytest using pip. Could this be related? And if so, what is the correct way to install pytest in this case?

EDIT 2:

One of the paths in sys.path is /usr/src/app/ which is a docker volume lined to /my/local/path/myproject/.

Should the volume be /my/local/path/myproject/myproject/ instead?

Answer 1

Not sure if this solution was specific to my problem, but I simply add __init__.py to my tests folder and that solved the problem.

Answer 2

Solution: use the PYTHONPATH env. var

PYTHONPATH=. pytest

As mentioned by @J_H, you need to explicitly add the root directory of your project, since pytest only adds to sys.path directories where test files are (which is why @Mak2006's answer worked.)

---

Good practice: use a Makefile or some other automation tool

If you do not want to type that long command all the time, one option is to create a Makefile in your project's root dir with, e.g., the following:

.PHONY: test
test:
    PYTHONPATH=. pytest

Which allows you to simply run:

make test

Another common alternative is to use some standard testing tool, such as tox.

Answer 3

Be sure to include . dot in the $PYTHONPATH env var.

Use $ python -m site, or this code fragment to debug such issues:

import pprint
import sys
pprint.pprint(sys.path)

---

Your question managed to use myproject at three different levels. At least during debugging you might want to use three distinct names, to reduce possible confusion.

Answer 4

In my case I added a __init__.py to my test directory with this inside it:

import sys
sys.path.append('.')

My app code is at the same level as my test directory.

Answer 5

Kept everything same and just added a blank test file at the root folder .. Solved

Here are the findings, this problem really bugged me for a while. My folder structure was

mathapp/
    - server.py  
    - configuration.py 
    - __init__.py 
    - static/ 
       - home.html  
tests/            
    - functional 
       - test_errors.py 
    - unit  
       - test_add.py

and pytest would complain with the ModuleNotFoundError.

I introduced a mock test file at the same level as mathsapp and tests directory. The file contained nothing. Now pytest does not complain.

Result without the file

$ pytest
============================= test session starts =============================
platform win32 -- Python 3.8.2, pytest-5.4.2, py-1.8.1, pluggy-0.13.1
rootdir: C:\mak2006\workspace\0github\python-rest-app-cont
collected 1 item / 1 error

=================================== ERRORS ====================================
_______________ ERROR collecting tests/functional/test_func.py ________________
ImportError while importing test module 'C:\mainak\workspace\0github\python-rest-app-cont\tests\functional\test_func.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
tests\functional\test_func.py:4: in <module>
    from mathapp.service import sum
E   ModuleNotFoundError: No module named 'mathapp'
=========================== short test summary info ===========================
ERROR tests/functional/test_func.py
!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
============================== 1 error in 0.24s ===============================

Results with the file

$ pytest
============================= test session starts =============================
platform win32 -- Python 3.8.2, pytest-5.4.2, py-1.8.1, pluggy-0.13.1
rootdir: C:\mak2006\workspace\0github\python-rest-app-cont
collected 2 items

tests\functional\test_func.py .                                          [ 50%]
tests\unit\test_unit.py .                                                [100%]

============================== 2 passed in 0.11s ==============================

Answer 6

In my case it is because I installed pytest on the system level but not in my virtual environment.

You can test this by python -m pytest. If you see ModuleNotFoundError: No module named 'pytest' then your pytest is at the system level.

Install pytest when the virtual environment is activated will fix this.

Answer 7

So it seems that the sys.path has to include the application directory rather than the project root folder containing the application directory and test directory.

So in my case /my/local/path/myproject/myproject/ had to be in sys.path rather than /my/local/path/myproject/.

Then I could run pytest in /my/local/path/myproject/ (didn't need python -m pytest). This meant that the modules within /myproject/myproject/ could find each other and the tests as well without any namespace nesting.

So my tests looked like

 from moduleone import ModuleOne
 import pytest

 def test_fun():
     assert ModuleOne.example_func() == True

That said, there seem to be many gotchas, so I have no idea if this is correct..

Answer 8

Using poetry and pytest 5.4.3, I had the following structure (some folders / files have been removed for clarity):

project structure

.
├── my_app
│   ├── __init__.py
│   ├── main.py
│   ├── model.py
│   └── orm.py
├── poetry.lock
├── pyproject.toml
├── README.rst
└── tests
    ├── __init__.py
    ├── conftest.py
    ├── test_my_app.py
    └── utilities
        └── db_postgresql_inmemory.py

tests/conftest.py

pytest_plugins = [
    "utilities.db_postgresql_inmemory",
]

which generated a module not found error for the fixture:

ImportError: Error importing plugin "utilities.db_postgresql_inmemory": No module named 'utilities'

None of the other answers have worked for me, as I have tried to add:

[me@linux ~/code/my_app]touch tests/utilities/__init__.py
[me@linux ~/code/my_app]touch ./test_blank.py

I could make the import from conftest.py work by REMOVING both __init__.py files:

[me@linux ~/code/my_app]rm tests/utilities/__init__.py tests/__init__.py

Answer 9

I suggest you have a code structure like this:

myproject/
  helpers/
    moduleone.py
    moduletwo.py
  tests/
    myproject_test.py
  conftest.py

And the content of conftest.py file is:

pytest_plugins = ['helpers']

Run pytest again.

Answer 10

I ran into this issue as well and am using poetry for dependency management and direnv for my project specific environment variables. Please note, I am relatively new to Python so I don't know if this is the correct fix.

Here is my entire .envrc file:

layout_poetry() {
  if [[ ! -f pyproject.toml ]]; then
    log_error 'No pyproject.toml found.  Use `poetry new` or `poetry init` to create one first.'
    exit 2
  fi

  local VENV=$(poetry env list --full-path | cut -d' ' -f1)
  if [[ -z $VENV || ! -d $VENV/bin ]]; then
    log_error 'No created poetry virtual environment found.  Use `poetry install` to create one first.'
    exit 2
  fi
  VENV=$VENV/bin
  export VIRTUAL_ENV=$(echo "$VENV" | rev | cut -d'/' -f2- | rev)
  export POETRY_ACTIVE=1
  PATH_add "$VENV"
}

layout poetry
export PYTHONDONTWRITEBYTECODE=1
export PYTHONPATH="$PWD/project_name"

I don't know if I need to layout poetry because it is supposed to be creating virtual environments for us already but this is what I coworker recommended so I went with it. Layout poetry also didn't work without that function and it didn't like when I added it to my zshenv so I added it here.

For this specific question, the last line is the money maker.

Answer 11

ANOTHER SUGGESTION

See this answer: https://stackoverflow.com/a/69691436/595305

Answer 12

I was facing the issue which i resolved by

• Installing pytest at the root of my project using pip install pytest
• Adding blank __init__.py in the sibling of my test_file.py which i wanted to execute.

Answer 13

In my case, I've created a separate app for testing with both __init__.py and conftest.py at the same level. After deleting __init__.py error was gone.

Credit goes to qci-amos

Answer 14

I have resolved it by adding export PYTHONPATH="your root dir/src"

i.e.
export PYTHONPATH="/builds/project/src"

poetry run pytest .....

Answer 15

The simplest solution I found was to manually add my target module to syspath. Lets say you have a structure like this:

flaskapp
- src
  -- app.py
  -- utils
  -- ...
- tests
docs
venv

This makes my test folder a sibling to my module's src folder. If I start putting test_* files that need to import some of the module's code, I can simply:

import src.utils.calculator

And this would be fine until I try to import a file that imports another file from the module. The solution is simple: add a __init__.py to your tests folder, and put this line inside:

import sys, os
sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '../src')))

And just modify the last part relative to your module location and folder name

Answer 16

For me, when I was checking my project structure I found parent directory and sub directory having same names. When I changed the directory name, I got it working. So,

# Did not work
- same_name_project/
    - same_name_project/
    - tests/

# Worked
- different_named_project/
    - a_unique_directory/
    - tests/