I have following directory structure.
root-folder
– config-folder
json-file.config
– class-folder
classfile.py
– tests
pytest-file1.py
Now, I need to use a class named myclass from classfile.py in my test/pytestfile1.py. How can I import that class in my pytest file??
To import the myclass from classfile.py into your pytest-file1.py, you can use a relative import assuming your Python environment treats the root-folder as the top-level package. Here’s how you can do it:
1. Relative Import
In your pytest-file1.py, use the following import statement:
from ..class_folder.classfile import myclass
This assumes that:
classfile.py contains myclass.
You are running the tests from the root-folder level (or using a testing framework like pytest that manages imports correctly).
2. Absolute Import (from the root folder)
If you’re running pytest from the root-folder, you can use an absolute import like this:
from class_folder.classfile import myclass
3.Ensure root-folder is in PYTHONPATH
In Python, the PYTHONPATH is an environment variable that specifies which directories Python should search for modules when importing. By default, Python searches for modules in the standard library and in the current working directory. However, sometimes you need to tell Python where to look, especially when dealing with custom directory structures like yours.
Why is PYTHONPATH important?
Your directory structure looks like this:
root-folder
– config-folder
json-file.config
– class-folder
classfile.py (contains ‘myclass’)
– tests
pytest-file1.py
To import myclass from classfile.py in pytest-file1.py, Python needs to know where the class_folder is located. If the root-folder is not in the PYTHONPATH, Python won’t be able to find class_folder or classfile, leading to an ImportError.
How to set PYTHONPATH
1. Temporary way using the command line (recommended for testing)
Before running your tests, you can set PYTHONPATH to include the root-folder so that Python can find the class_folder.
– On Linux/macOS, run:
PYTHONPATH=. pytest
Here, . refers to the current directory (root-folder). This temporarily sets PYTHONPATH to the current directory for that session, allowing Python to find class_folder and any other modules under root-folder.
– On Windows, the equivalent command is:
set PYTHONPATH=. && pytest
This sets PYTHONPATH for the current terminal session.
2. Permanent way by setting it in your environment
You can add the root-folder to PYTHONPATH permanently by configuring your system environment variables.
– On Linux/macOS (in your .bashrc, .zshrc, etc.):
export PYTHONPATH=/path/to/root-folder:$PYTHONPATH
This appends root-folder to the existing PYTHONPATH. After saving, run:
source ~/.bashrc # or source ~/.zshrc
– On Windows:
Open the System Properties (right-click “This PC” or “Computer”, then choose “Properties”).
Go to Advanced system settings > Environment Variables.
Under System Variables, find the PYTHONPATH variable (create it if it doesn’t exist).
Add the path to root-folder in the value.
This method ensures that every time you run Python, root-folder is part of its module search path.”
What happens after setting PYTHONPATH?
After setting PYTHONPATH to root-folder, you can use an absolute import in your pytest-file1.py:
from class_folder.classfile import myclass
Now, when Python sees this import statement, it knows to look in the root-folder for the class_folder and then import classfile.py.