How does pytest find files to test? - python

I know how py.test discovers tests to run, but I don't know how to make the tests refer to the files that contains the code to test.
My project looks like this:
arith.py
tests/
test_airth.py
In my project root directory, I have the file arith.py with
def plus(x, y):
return x + y
In the file tests/test_arith.py I have
import arith
def test_plus():
assert arith.plus(3, 5) == 8
When I run, in the project root directory,
pytest
It discovers my test file, because I followed the test discovery rules. But pytest replies with
ImportError while importing test module tests/test_arith.py'
I ran pytest from the project root, so why does it not like my import? It wants to find the files that I am testing in the tests directory!
How can I set up the imports properly, so that my test files in the tests/ directory, can see the files under test which are in the project root directory? (The examples in pytest's documentation seem to not do anything special...perhaps the tests are in the same directory as the files under test? They describe test discovery in great detail, but I must have missed how to set up the tests so they can see the code they are testing.)

Assuming you have a layout like this (which is what I do):
.
├── myprogram
│   ├── __init__.py
│   ├── core.py
│   └── db.py
├── setup.py
└── tests
├── test_core.py
└── test_db.py
You should be invoking pytest like so:
py.test tests
I'm fairly sure that's an absolute/relative path to the tests directory. This also assumes that you have done something like python -m pip install -e . in your root directory. And you have a .git or .hg folder there, too :)
It's a little strange so much is needed. Surely there is a better way?
Actually that is the best way. I don't think it's controversial to declare that the best way to distribute your Python application is as a Python package, preferably a wheel. To do that, you're probably going to need a setup.py.
By installing your package (preferably in a venv/virtualenv sandbox) you're ensuring that you know what packages are required to install/run yours. If your package is installed that means that any script that does import myprogram (using my example layout) will be able to import your package. Which is what you'll be doing in your test suite.
Then your test discovery is as simple as telling pytest where to find it.

Related

Pytest import errors [duplicate]

I used easy_install to install pytest on a Mac and started writing tests for a project with a file structure likes so:
repo/
|--app.py
|--settings.py
|--models.py
|--tests/
|--test_app.py
Run py.test while in the repo directory, and everything behaves as you would expect.
But when I try that same thing on either Linux or Windows (both have pytest 2.2.3 on them), it barks whenever it hits its first import of something from my application path. For instance, from app import some_def_in_app.
Do I need to be editing my PATH to run py.test on these systems?
I'm not sure why py.test does not add the current directory in the PYTHONPATH itself, but here's a workaround (to be executed from the root of your repository):
python -m pytest tests/
It works because Python adds the current directory in the PYTHONPATH for you.
Recommended approach for pytest>=7: use the pythonpath setting
Recently, pytest has added a new core plugin that supports sys.path modifications via the pythonpath configuration value. The solution is thus much simpler now and doesn't require any workarounds anymore:
pyproject.toml example:
[tool.pytest.ini_options]
pythonpath = [
"."
]
pytest.ini example:
[pytest]
pythonpath = .
The path entries are calculated relative to the rootdir, thus . adds repo directory to sys.path in this case.
Multiple path entries are also allowed: for a layout
repo/
├── src/
| └── lib.py
├── app.py
└── tests
├── test_app.py
└── test_lib.py
the configuration
[tool.pytest.ini_options]
pythonpath = [
".", "src",
]
or
[pytest]
pythonpath = . src
will add both app and lib modules to sys.path, so
import app
import lib
will both work.
Original answer (not recommended for recent pytest versions; use for pytest<7 only): conftest solution
The least invasive solution is adding an empty file named conftest.py in the repo/ directory:
$ touch repo/conftest.py
That's it. No need to write custom code for mangling the sys.path or remember to drag PYTHONPATH along, or placing __init__.py into dirs where it doesn't belong (using python -m pytest as suggested in Apteryx's answer is a good solution though!).
The project directory afterwards:
repo
├── conftest.py
├── app.py
├── settings.py
├── models.py
└── tests
└── test_app.py
Explanation
pytest looks for the conftest modules on test collection to gather custom hooks and fixtures, and in order to import the custom objects from them, pytest adds the parent directory of the conftest.py to the sys.path (in this case the repo directory).
Other project structures
If you have other project structure, place the conftest.py in the package root dir (the one that contains packages but is not a package itself, so does not contain an __init__.py), for example:
repo
├── conftest.py
├── spam
│ ├── __init__.py
│ ├── bacon.py
│ └── egg.py
├── eggs
│ ├── __init__.py
│ └── sausage.py
└── tests
├── test_bacon.py
└── test_egg.py
src layout
Although this approach can be used with the src layout (place conftest.py in the src dir):
repo
├── src
│ ├── conftest.py
│ ├── spam
│ │ ├── __init__.py
│ │ ├── bacon.py
│ │ └── egg.py
│ └── eggs
│ ├── __init__.py
│ └── sausage.py
└── tests
├── test_bacon.py
└── test_egg.py
beware that adding src to PYTHONPATH mitigates the meaning and benefits of the src layout! You will end up with testing the code from repository and not the installed package. If you need to do it, maybe you don't need the src dir at all.
Where to go from here
Of course, conftest modules are not just some files to help the source code discovery; it's where all the project-specific enhancements of the pytest framework and the customization of your test suite happen. pytest has a lot of information on conftest modules scattered throughout their docs; start with conftest.py: local per-directory plugins
Also, SO has an excellent question on conftest modules: In py.test, what is the use of conftest.py files?
I had the same problem. I fixed it by adding an empty __init__.py file to my tests directory.
Yes, the source folder is not in Python's path if you cd to the tests directory.
You have two choices:
Add the path manually to the test files. Something like this:
import sys, os
myPath = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, myPath + '/../')
Run the tests with the env var PYTHONPATH=../.
Run pytest itself as a module with:
python -m pytest tests
This happens when the project hierarchy is, for example, package/src package/tests and in tests you import from src. Executing as a module will consider imports as absolute rather than relative to the execution location.
You can run with PYTHONPATH in project root
PYTHONPATH=. py.test
Or use pip install as editable import
pip install -e . # install package using setup.py in editable mode
I had the same problem in Flask.
When I added:
__init__.py
to the tests folder, the problem disappeared :)
Probably the application couldn't recognize folder tests as a module.
I created this as an answer to your question and my own confusion. I hope it helps. Pay attention to PYTHONPATH in both the py.test command line and in the tox.ini.
https://github.com/jeffmacdonald/pytest_test
Specifically: You have to tell py.test and tox where to find the modules you are including.
With py.test you can do this:
PYTHONPATH=. py.test
And with tox, add this to your tox.ini:
[testenv]
deps= -r{toxinidir}/requirements.txt
commands=py.test
setenv =
PYTHONPATH = {toxinidir}
I fixed it by removing the top-level __init__.py in the parent folder of my sources.
I started getting weird ConftestImportFailure: ImportError('No module named ... errors when I had accidentally added __init__.py file to my src directory (which was not supposed to be a Python package, just a container of all source).
It is a bit of a shame that this is an issue in Python... But just adding this environment variable is the most comfortable way, IMO:
export PYTHONPATH=$PYTHONPATH:.
You can put this line in you .zshrc or .bashrc file.
I was having the same problem when following the Flask tutorial and I found the answer on the official Pytest documentation.
It's a little shift from the way I (and I think many others) are used to do things.
You have to create a setup.py file in your project's root directory with at least the following two lines:
from setuptools import setup, find_packages
setup(name="PACKAGENAME", packages=find_packages())
where PACKAGENAME is your app's name. Then you have to install it with pip:
pip install -e .
The -e flag tells pip to install the package in editable or "develop" mode. So the next time you run pytest it should find your app in the standard PYTHONPATH.
I had a similar issue. pytest did not recognize a module installed in the environment I was working in.
I resolved it by also installing pytest into the same environment.
Also if you run pytest within your virtual environment make sure pytest module is installed within your virtual environment. Activate your virtual environment and run pip install pytest.
For me the problem was tests.py generated by Django along with tests directory. Removing tests.py solved the problem.
I got this error as I used relative imports incorrectly. In the OP example, test_app.py should import functions using e.g.
from repo.app import *
However liberally __init__.py files are scattered around the file structure, this does not work and creates the kind of ImportError seen unless the files and test files are in the same directory.
from app import *
Here's an example of what I had to do with one of my projects:
Here’s my project structure:
microbit/
microbit/activity_indicator/activity_indicator.py
microbit/tests/test_activity_indicator.py
To be able to access activity_indicator.py from test_activity_indicator.py I needed to:
start test_activity_indicatory.py with the correct relative import:
from microbit.activity_indicator.activity_indicator import *
put __init__.py files throughout the project structure:
microbit/
microbit/__init__.py
microbit/activity_indicator/__init__.py
microbit/activity_indicator/activity_indicator.py
microbit/tests/__init__.py
microbit/tests/test_activity_indicator.py
According to a post on Medium by Dirk Avery (and supported by my personal experience) if you're using a virtual environment for your project then you can't use a system-wide install of pytest; you have to install it in the virtual environment and use that install.
In particular, if you have it installed in both places then simply running the pytest command won't work because it will be using the system install. As the other answers have described, one simple solution is to run python -m pytest instead of pytest; this works because it uses the environment's version of pytest. Alternatively, you can just uninstall the system's version of pytest; after reactivating the virtual environment the pytest command should work.
I was getting this error due to something even simpler (you could even say trivial). I hadn't installed the pytest module. So a simple apt install python-pytest fixed it for me.
'pytest' would have been listed in setup.py as a test dependency. Make sure you install the test requirements as well.
Since no one has suggested it, you could also pass the path to the tests in your pytest.ini file:
[pytest]
...
testpaths = repo/tests
See documentation: https://docs.pytest.org/en/6.2.x/customize.html#pytest-ini
Side effect for Visual Studio Code: it should pick up the unit test in the UI.
We have fixed the issue by adding the following environment variable.
PYTHONPATH=${PYTHONPATH}:${PWD}/src:${PWD}/test
As pointed out by Luiz Lezcano Arialdi, the correct solution is to install your package as an editable package.
Since I am using Pipenv, I thought about adding to his answer a step-by-step how to install the current path as an edible with Pipenv, allowing to run pytest without the need of any mangling code or lose files.
You will need to have the following minimal folder structure (documentation):
package/
package/
__init__.py
module.py
tests/
module_test.py
setup.py
setup.py mostly has the following minium code (documentation):
import setuptools
setuptools.setup(name='package', # Change to your package name
packages=setuptools.find_packages())
Then you just need to run pipenv install --dev -e . and Pipenv will install the current path as an editable package (the --dev flag is optional) (documentation).
Now you should be able to run pytest without problems.
If this pytest error appears not for your own package, but for a Git-installed package in your package's requirements.txt, the solution is to switch to editable installation mode.
For example, suppose your package's requirements.txt had the following line:
git+https://github.com/foo/bar.git
You would instead replace it with the following:
-e git+https://github.com/foo/bar.git#egg=bar
If nothing works, make sure your test_module.py is listed under the correct src directory.
Sometimes it will give ModuleNotFoundError not because modules are misplaced or export PYTHONPATH="${PWD}:${PYTHONPATH}" is not working, its because test_module.py is placed into a wrong directory under the tests folder.
it should be 1-to-1 mapping relation recursively instead of the root folder should be named as "tests" and the name of the file that include test code should starts with "test_",
for example,
./nlu_service/models/transformers.py
./tests/models/test_transformers.py
This was my experience.
Very often the tests were interrupted due to module being unable to be imported.
After research, I found out that the system is looking at the file in the wrong place and we can easily overcome the problem by copying the file, containing the module, in the same folder as stated, in order to be properly imported.
Another solution proposal would be to change the declaration for the import and show MutPy the correct path of the unit. However, due to the fact that multiple units can have this dependency, meaning we need to commit changes also in their declarations, we prefer to simply move the unit to the folder.
My solution:
Create the conftest.py file in the test directory containing:
import os
import sys
sys.path.insert(0, os.path.dirname(os.path.realpath(__file__)) + "/relative/path/to/code/")
This will add the folder of interest to the Python interpreter path without modifying every test file, setting environment variable or messing with absolute/relative paths.

When to assume dash m usage and avoid __init__?

For Python 3.
I just started learning Python. I have PHP and Ruby background.
Currently very confused with modules, __init__ and python -m.
At the moment I have the following:
modules/practice.py
tests/test_practice.py
In practice.py
class First:
def attempt(self):
return 'attempted'
In test_practice.py
from modules.practice import First
class TestMain:
def test_attempt(self):
first = First()
attempted = first.attempt()
assert attempted is 'attempted'
When I run pytest I get an error ModuleNotFoundError: No module named 'modules
When I run python -m pytest test is green.
However, if I add __init__.py files in modules and tests, both are green.
After trying to find out answers on my own I confess I am not sure I am getting it.
Why pytest does not work without __init__?
When working on a project, when people assume python -m will be used and when people add the __init__.py files instead?
Do not add an __init__.py file into the tests directory.
You should add an __init__.py file into the modules directory.
Ideally it should be possible to run the test suite with either pytest or python -m pytest. For this to work, the parent directory of modules needs to be present on sys.path. Usually you would do this by writing a setup.py file for the package and installing your code in "editable" mode. The tests run against the installed code linked in site-packages.
If you don't want to write a setup.py file at this stage, you can either export an environment variable:
export PYTHONPATH=/path/to/parent_of_modules
Or you can inject to sys.path directly from conftest.py file, which gets imported first:
.
├── modules
│   ├── __init__.py
│   └── practice.py
└── tests
├── conftest.py
└── test_practice.py
Example:
# conftest.py
import os
import sys
here = os.path.dirname(os.path.abspath(__file__))
sys.path.append(os.path.dirname(here))

What am I missing in running a very simple `py.test` test within a tox setup? [duplicate]

I used easy_install to install pytest on a Mac and started writing tests for a project with a file structure likes so:
repo/
|--app.py
|--settings.py
|--models.py
|--tests/
|--test_app.py
Run py.test while in the repo directory, and everything behaves as you would expect.
But when I try that same thing on either Linux or Windows (both have pytest 2.2.3 on them), it barks whenever it hits its first import of something from my application path. For instance, from app import some_def_in_app.
Do I need to be editing my PATH to run py.test on these systems?
I'm not sure why py.test does not add the current directory in the PYTHONPATH itself, but here's a workaround (to be executed from the root of your repository):
python -m pytest tests/
It works because Python adds the current directory in the PYTHONPATH for you.
Recommended approach for pytest>=7: use the pythonpath setting
Recently, pytest has added a new core plugin that supports sys.path modifications via the pythonpath configuration value. The solution is thus much simpler now and doesn't require any workarounds anymore:
pyproject.toml example:
[tool.pytest.ini_options]
pythonpath = [
"."
]
pytest.ini example:
[pytest]
pythonpath = .
The path entries are calculated relative to the rootdir, thus . adds repo directory to sys.path in this case.
Multiple path entries are also allowed: for a layout
repo/
├── src/
| └── lib.py
├── app.py
└── tests
├── test_app.py
└── test_lib.py
the configuration
[tool.pytest.ini_options]
pythonpath = [
".", "src",
]
or
[pytest]
pythonpath = . src
will add both app and lib modules to sys.path, so
import app
import lib
will both work.
Original answer (not recommended for recent pytest versions; use for pytest<7 only): conftest solution
The least invasive solution is adding an empty file named conftest.py in the repo/ directory:
$ touch repo/conftest.py
That's it. No need to write custom code for mangling the sys.path or remember to drag PYTHONPATH along, or placing __init__.py into dirs where it doesn't belong (using python -m pytest as suggested in Apteryx's answer is a good solution though!).
The project directory afterwards:
repo
├── conftest.py
├── app.py
├── settings.py
├── models.py
└── tests
└── test_app.py
Explanation
pytest looks for the conftest modules on test collection to gather custom hooks and fixtures, and in order to import the custom objects from them, pytest adds the parent directory of the conftest.py to the sys.path (in this case the repo directory).
Other project structures
If you have other project structure, place the conftest.py in the package root dir (the one that contains packages but is not a package itself, so does not contain an __init__.py), for example:
repo
├── conftest.py
├── spam
│ ├── __init__.py
│ ├── bacon.py
│ └── egg.py
├── eggs
│ ├── __init__.py
│ └── sausage.py
└── tests
├── test_bacon.py
└── test_egg.py
src layout
Although this approach can be used with the src layout (place conftest.py in the src dir):
repo
├── src
│ ├── conftest.py
│ ├── spam
│ │ ├── __init__.py
│ │ ├── bacon.py
│ │ └── egg.py
│ └── eggs
│ ├── __init__.py
│ └── sausage.py
└── tests
├── test_bacon.py
└── test_egg.py
beware that adding src to PYTHONPATH mitigates the meaning and benefits of the src layout! You will end up with testing the code from repository and not the installed package. If you need to do it, maybe you don't need the src dir at all.
Where to go from here
Of course, conftest modules are not just some files to help the source code discovery; it's where all the project-specific enhancements of the pytest framework and the customization of your test suite happen. pytest has a lot of information on conftest modules scattered throughout their docs; start with conftest.py: local per-directory plugins
Also, SO has an excellent question on conftest modules: In py.test, what is the use of conftest.py files?
I had the same problem. I fixed it by adding an empty __init__.py file to my tests directory.
Yes, the source folder is not in Python's path if you cd to the tests directory.
You have two choices:
Add the path manually to the test files. Something like this:
import sys, os
myPath = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, myPath + '/../')
Run the tests with the env var PYTHONPATH=../.
Run pytest itself as a module with:
python -m pytest tests
This happens when the project hierarchy is, for example, package/src package/tests and in tests you import from src. Executing as a module will consider imports as absolute rather than relative to the execution location.
You can run with PYTHONPATH in project root
PYTHONPATH=. py.test
Or use pip install as editable import
pip install -e . # install package using setup.py in editable mode
I had the same problem in Flask.
When I added:
__init__.py
to the tests folder, the problem disappeared :)
Probably the application couldn't recognize folder tests as a module.
I created this as an answer to your question and my own confusion. I hope it helps. Pay attention to PYTHONPATH in both the py.test command line and in the tox.ini.
https://github.com/jeffmacdonald/pytest_test
Specifically: You have to tell py.test and tox where to find the modules you are including.
With py.test you can do this:
PYTHONPATH=. py.test
And with tox, add this to your tox.ini:
[testenv]
deps= -r{toxinidir}/requirements.txt
commands=py.test
setenv =
PYTHONPATH = {toxinidir}
I fixed it by removing the top-level __init__.py in the parent folder of my sources.
I started getting weird ConftestImportFailure: ImportError('No module named ... errors when I had accidentally added __init__.py file to my src directory (which was not supposed to be a Python package, just a container of all source).
It is a bit of a shame that this is an issue in Python... But just adding this environment variable is the most comfortable way, IMO:
export PYTHONPATH=$PYTHONPATH:.
You can put this line in you .zshrc or .bashrc file.
I was having the same problem when following the Flask tutorial and I found the answer on the official Pytest documentation.
It's a little shift from the way I (and I think many others) are used to do things.
You have to create a setup.py file in your project's root directory with at least the following two lines:
from setuptools import setup, find_packages
setup(name="PACKAGENAME", packages=find_packages())
where PACKAGENAME is your app's name. Then you have to install it with pip:
pip install -e .
The -e flag tells pip to install the package in editable or "develop" mode. So the next time you run pytest it should find your app in the standard PYTHONPATH.
I had a similar issue. pytest did not recognize a module installed in the environment I was working in.
I resolved it by also installing pytest into the same environment.
Also if you run pytest within your virtual environment make sure pytest module is installed within your virtual environment. Activate your virtual environment and run pip install pytest.
For me the problem was tests.py generated by Django along with tests directory. Removing tests.py solved the problem.
I got this error as I used relative imports incorrectly. In the OP example, test_app.py should import functions using e.g.
from repo.app import *
However liberally __init__.py files are scattered around the file structure, this does not work and creates the kind of ImportError seen unless the files and test files are in the same directory.
from app import *
Here's an example of what I had to do with one of my projects:
Here’s my project structure:
microbit/
microbit/activity_indicator/activity_indicator.py
microbit/tests/test_activity_indicator.py
To be able to access activity_indicator.py from test_activity_indicator.py I needed to:
start test_activity_indicatory.py with the correct relative import:
from microbit.activity_indicator.activity_indicator import *
put __init__.py files throughout the project structure:
microbit/
microbit/__init__.py
microbit/activity_indicator/__init__.py
microbit/activity_indicator/activity_indicator.py
microbit/tests/__init__.py
microbit/tests/test_activity_indicator.py
According to a post on Medium by Dirk Avery (and supported by my personal experience) if you're using a virtual environment for your project then you can't use a system-wide install of pytest; you have to install it in the virtual environment and use that install.
In particular, if you have it installed in both places then simply running the pytest command won't work because it will be using the system install. As the other answers have described, one simple solution is to run python -m pytest instead of pytest; this works because it uses the environment's version of pytest. Alternatively, you can just uninstall the system's version of pytest; after reactivating the virtual environment the pytest command should work.
I was getting this error due to something even simpler (you could even say trivial). I hadn't installed the pytest module. So a simple apt install python-pytest fixed it for me.
'pytest' would have been listed in setup.py as a test dependency. Make sure you install the test requirements as well.
Since no one has suggested it, you could also pass the path to the tests in your pytest.ini file:
[pytest]
...
testpaths = repo/tests
See documentation: https://docs.pytest.org/en/6.2.x/customize.html#pytest-ini
Side effect for Visual Studio Code: it should pick up the unit test in the UI.
We have fixed the issue by adding the following environment variable.
PYTHONPATH=${PYTHONPATH}:${PWD}/src:${PWD}/test
As pointed out by Luiz Lezcano Arialdi, the correct solution is to install your package as an editable package.
Since I am using Pipenv, I thought about adding to his answer a step-by-step how to install the current path as an edible with Pipenv, allowing to run pytest without the need of any mangling code or lose files.
You will need to have the following minimal folder structure (documentation):
package/
package/
__init__.py
module.py
tests/
module_test.py
setup.py
setup.py mostly has the following minium code (documentation):
import setuptools
setuptools.setup(name='package', # Change to your package name
packages=setuptools.find_packages())
Then you just need to run pipenv install --dev -e . and Pipenv will install the current path as an editable package (the --dev flag is optional) (documentation).
Now you should be able to run pytest without problems.
If this pytest error appears not for your own package, but for a Git-installed package in your package's requirements.txt, the solution is to switch to editable installation mode.
For example, suppose your package's requirements.txt had the following line:
git+https://github.com/foo/bar.git
You would instead replace it with the following:
-e git+https://github.com/foo/bar.git#egg=bar
If nothing works, make sure your test_module.py is listed under the correct src directory.
Sometimes it will give ModuleNotFoundError not because modules are misplaced or export PYTHONPATH="${PWD}:${PYTHONPATH}" is not working, its because test_module.py is placed into a wrong directory under the tests folder.
it should be 1-to-1 mapping relation recursively instead of the root folder should be named as "tests" and the name of the file that include test code should starts with "test_",
for example,
./nlu_service/models/transformers.py
./tests/models/test_transformers.py
This was my experience.
Very often the tests were interrupted due to module being unable to be imported.
After research, I found out that the system is looking at the file in the wrong place and we can easily overcome the problem by copying the file, containing the module, in the same folder as stated, in order to be properly imported.
Another solution proposal would be to change the declaration for the import and show MutPy the correct path of the unit. However, due to the fact that multiple units can have this dependency, meaning we need to commit changes also in their declarations, we prefer to simply move the unit to the folder.
My solution:
Create the conftest.py file in the test directory containing:
import os
import sys
sys.path.insert(0, os.path.dirname(os.path.realpath(__file__)) + "/relative/path/to/code/")
This will add the folder of interest to the Python interpreter path without modifying every test file, setting environment variable or messing with absolute/relative paths.

Path problems with pytest [duplicate]

I used easy_install to install pytest on a Mac and started writing tests for a project with a file structure likes so:
repo/
|--app.py
|--settings.py
|--models.py
|--tests/
|--test_app.py
Run py.test while in the repo directory, and everything behaves as you would expect.
But when I try that same thing on either Linux or Windows (both have pytest 2.2.3 on them), it barks whenever it hits its first import of something from my application path. For instance, from app import some_def_in_app.
Do I need to be editing my PATH to run py.test on these systems?
I'm not sure why py.test does not add the current directory in the PYTHONPATH itself, but here's a workaround (to be executed from the root of your repository):
python -m pytest tests/
It works because Python adds the current directory in the PYTHONPATH for you.
Recommended approach for pytest>=7: use the pythonpath setting
Recently, pytest has added a new core plugin that supports sys.path modifications via the pythonpath configuration value. The solution is thus much simpler now and doesn't require any workarounds anymore:
pyproject.toml example:
[tool.pytest.ini_options]
pythonpath = [
"."
]
pytest.ini example:
[pytest]
pythonpath = .
The path entries are calculated relative to the rootdir, thus . adds repo directory to sys.path in this case.
Multiple path entries are also allowed: for a layout
repo/
├── src/
| └── lib.py
├── app.py
└── tests
├── test_app.py
└── test_lib.py
the configuration
[tool.pytest.ini_options]
pythonpath = [
".", "src",
]
or
[pytest]
pythonpath = . src
will add both app and lib modules to sys.path, so
import app
import lib
will both work.
Original answer (not recommended for recent pytest versions; use for pytest<7 only): conftest solution
The least invasive solution is adding an empty file named conftest.py in the repo/ directory:
$ touch repo/conftest.py
That's it. No need to write custom code for mangling the sys.path or remember to drag PYTHONPATH along, or placing __init__.py into dirs where it doesn't belong (using python -m pytest as suggested in Apteryx's answer is a good solution though!).
The project directory afterwards:
repo
├── conftest.py
├── app.py
├── settings.py
├── models.py
└── tests
└── test_app.py
Explanation
pytest looks for the conftest modules on test collection to gather custom hooks and fixtures, and in order to import the custom objects from them, pytest adds the parent directory of the conftest.py to the sys.path (in this case the repo directory).
Other project structures
If you have other project structure, place the conftest.py in the package root dir (the one that contains packages but is not a package itself, so does not contain an __init__.py), for example:
repo
├── conftest.py
├── spam
│ ├── __init__.py
│ ├── bacon.py
│ └── egg.py
├── eggs
│ ├── __init__.py
│ └── sausage.py
└── tests
├── test_bacon.py
└── test_egg.py
src layout
Although this approach can be used with the src layout (place conftest.py in the src dir):
repo
├── src
│ ├── conftest.py
│ ├── spam
│ │ ├── __init__.py
│ │ ├── bacon.py
│ │ └── egg.py
│ └── eggs
│ ├── __init__.py
│ └── sausage.py
└── tests
├── test_bacon.py
└── test_egg.py
beware that adding src to PYTHONPATH mitigates the meaning and benefits of the src layout! You will end up with testing the code from repository and not the installed package. If you need to do it, maybe you don't need the src dir at all.
Where to go from here
Of course, conftest modules are not just some files to help the source code discovery; it's where all the project-specific enhancements of the pytest framework and the customization of your test suite happen. pytest has a lot of information on conftest modules scattered throughout their docs; start with conftest.py: local per-directory plugins
Also, SO has an excellent question on conftest modules: In py.test, what is the use of conftest.py files?
I had the same problem. I fixed it by adding an empty __init__.py file to my tests directory.
Yes, the source folder is not in Python's path if you cd to the tests directory.
You have two choices:
Add the path manually to the test files. Something like this:
import sys, os
myPath = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, myPath + '/../')
Run the tests with the env var PYTHONPATH=../.
Run pytest itself as a module with:
python -m pytest tests
This happens when the project hierarchy is, for example, package/src package/tests and in tests you import from src. Executing as a module will consider imports as absolute rather than relative to the execution location.
You can run with PYTHONPATH in project root
PYTHONPATH=. py.test
Or use pip install as editable import
pip install -e . # install package using setup.py in editable mode
I had the same problem in Flask.
When I added:
__init__.py
to the tests folder, the problem disappeared :)
Probably the application couldn't recognize folder tests as a module.
I created this as an answer to your question and my own confusion. I hope it helps. Pay attention to PYTHONPATH in both the py.test command line and in the tox.ini.
https://github.com/jeffmacdonald/pytest_test
Specifically: You have to tell py.test and tox where to find the modules you are including.
With py.test you can do this:
PYTHONPATH=. py.test
And with tox, add this to your tox.ini:
[testenv]
deps= -r{toxinidir}/requirements.txt
commands=py.test
setenv =
PYTHONPATH = {toxinidir}
I fixed it by removing the top-level __init__.py in the parent folder of my sources.
I started getting weird ConftestImportFailure: ImportError('No module named ... errors when I had accidentally added __init__.py file to my src directory (which was not supposed to be a Python package, just a container of all source).
It is a bit of a shame that this is an issue in Python... But just adding this environment variable is the most comfortable way, IMO:
export PYTHONPATH=$PYTHONPATH:.
You can put this line in you .zshrc or .bashrc file.
I was having the same problem when following the Flask tutorial and I found the answer on the official Pytest documentation.
It's a little shift from the way I (and I think many others) are used to do things.
You have to create a setup.py file in your project's root directory with at least the following two lines:
from setuptools import setup, find_packages
setup(name="PACKAGENAME", packages=find_packages())
where PACKAGENAME is your app's name. Then you have to install it with pip:
pip install -e .
The -e flag tells pip to install the package in editable or "develop" mode. So the next time you run pytest it should find your app in the standard PYTHONPATH.
I had a similar issue. pytest did not recognize a module installed in the environment I was working in.
I resolved it by also installing pytest into the same environment.
Also if you run pytest within your virtual environment make sure pytest module is installed within your virtual environment. Activate your virtual environment and run pip install pytest.
For me the problem was tests.py generated by Django along with tests directory. Removing tests.py solved the problem.
I got this error as I used relative imports incorrectly. In the OP example, test_app.py should import functions using e.g.
from repo.app import *
However liberally __init__.py files are scattered around the file structure, this does not work and creates the kind of ImportError seen unless the files and test files are in the same directory.
from app import *
Here's an example of what I had to do with one of my projects:
Here’s my project structure:
microbit/
microbit/activity_indicator/activity_indicator.py
microbit/tests/test_activity_indicator.py
To be able to access activity_indicator.py from test_activity_indicator.py I needed to:
start test_activity_indicatory.py with the correct relative import:
from microbit.activity_indicator.activity_indicator import *
put __init__.py files throughout the project structure:
microbit/
microbit/__init__.py
microbit/activity_indicator/__init__.py
microbit/activity_indicator/activity_indicator.py
microbit/tests/__init__.py
microbit/tests/test_activity_indicator.py
According to a post on Medium by Dirk Avery (and supported by my personal experience) if you're using a virtual environment for your project then you can't use a system-wide install of pytest; you have to install it in the virtual environment and use that install.
In particular, if you have it installed in both places then simply running the pytest command won't work because it will be using the system install. As the other answers have described, one simple solution is to run python -m pytest instead of pytest; this works because it uses the environment's version of pytest. Alternatively, you can just uninstall the system's version of pytest; after reactivating the virtual environment the pytest command should work.
I was getting this error due to something even simpler (you could even say trivial). I hadn't installed the pytest module. So a simple apt install python-pytest fixed it for me.
'pytest' would have been listed in setup.py as a test dependency. Make sure you install the test requirements as well.
Since no one has suggested it, you could also pass the path to the tests in your pytest.ini file:
[pytest]
...
testpaths = repo/tests
See documentation: https://docs.pytest.org/en/6.2.x/customize.html#pytest-ini
Side effect for Visual Studio Code: it should pick up the unit test in the UI.
We have fixed the issue by adding the following environment variable.
PYTHONPATH=${PYTHONPATH}:${PWD}/src:${PWD}/test
As pointed out by Luiz Lezcano Arialdi, the correct solution is to install your package as an editable package.
Since I am using Pipenv, I thought about adding to his answer a step-by-step how to install the current path as an edible with Pipenv, allowing to run pytest without the need of any mangling code or lose files.
You will need to have the following minimal folder structure (documentation):
package/
package/
__init__.py
module.py
tests/
module_test.py
setup.py
setup.py mostly has the following minium code (documentation):
import setuptools
setuptools.setup(name='package', # Change to your package name
packages=setuptools.find_packages())
Then you just need to run pipenv install --dev -e . and Pipenv will install the current path as an editable package (the --dev flag is optional) (documentation).
Now you should be able to run pytest without problems.
If this pytest error appears not for your own package, but for a Git-installed package in your package's requirements.txt, the solution is to switch to editable installation mode.
For example, suppose your package's requirements.txt had the following line:
git+https://github.com/foo/bar.git
You would instead replace it with the following:
-e git+https://github.com/foo/bar.git#egg=bar
If nothing works, make sure your test_module.py is listed under the correct src directory.
Sometimes it will give ModuleNotFoundError not because modules are misplaced or export PYTHONPATH="${PWD}:${PYTHONPATH}" is not working, its because test_module.py is placed into a wrong directory under the tests folder.
it should be 1-to-1 mapping relation recursively instead of the root folder should be named as "tests" and the name of the file that include test code should starts with "test_",
for example,
./nlu_service/models/transformers.py
./tests/models/test_transformers.py
This was my experience.
Very often the tests were interrupted due to module being unable to be imported.
After research, I found out that the system is looking at the file in the wrong place and we can easily overcome the problem by copying the file, containing the module, in the same folder as stated, in order to be properly imported.
Another solution proposal would be to change the declaration for the import and show MutPy the correct path of the unit. However, due to the fact that multiple units can have this dependency, meaning we need to commit changes also in their declarations, we prefer to simply move the unit to the folder.
My solution:
Create the conftest.py file in the test directory containing:
import os
import sys
sys.path.insert(0, os.path.dirname(os.path.realpath(__file__)) + "/relative/path/to/code/")
This will add the folder of interest to the Python interpreter path without modifying every test file, setting environment variable or messing with absolute/relative paths.

Recursive unittest discovery with python3 and without __init__.py files

I have project with the following directory structure:
.
├── requirements.txt
├── main.py
├── tests
├── unit
│ └── test_thing1.py
│ └── test_thing2.py
└── integration
└── test_integration_thing1.py
└── test_integration_thing2.py
I want to run all tests with one command. If I do python -m unittest discover, no tests are executed.
I found this question that suggest adding a __init__.py file to make packages out of the unit and integration folders. The solution works, and all tests are running this way.
But since I'm using python3 and __init__.py files are not required with implicit namespace packages, I was wondering if there was a way to make this works without those __init__.py files.
I looked into it, and think its most likely a bug.
So I created a python bug report and a PR which fixes the issue for me.
Clone it and see if it works for you as well, with the fix the best way of running discover was python -m unittest discover -s tests. Otherwise it will look in for example virtual environments that are below the top dir.
Note that namespace package is regular package.
You must not expect namespace package is treated same to regular package.
Read this article too.
https://dev.to/methane/don-t-omit-init-py-3hga
I do not see the point of forcing the creation of __init__.py in each subdirectory, at least in my case: I am testing a Python wrapper of C++ code, so I am not testing a Python module that I have implemented. Also there is a risk that I will forget to create some __init__.py files which would lead to silently skipped tests.
So here is a solution to not have to create __init__.py in each subdirectory:
import glob
import os
import unittest
def test_suite_from_recursive_discover(pattern):
test_files = glob.glob('**/{}'.format(pattern), recursive=True)
test_dirs = list(set(([os.path.dirname(os.path.abspath(test_file)) for test_file in test_files])))
suites = [unittest.TestLoader().discover(start_dir=d, pattern=pattern) for d in test_dirs]
suite = unittest.TestSuite(suites)
return suite
if __name__ == "__main__":
unittest.TextTestRunner().run(test_suite_from_recursive_discover('test*.py'))
Use pytest. It does discover tests in folders.
In your case you just need to install in via pip (pip install pytest) and then run in your root folder pytest tests.

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