Tutorial 3 – Setup Python Virtual Environment and install Selenium and Behave BDD
Welcome to the 3rd article in Behave BDD series!
What you will Learn :
About Python Virtual Environments
Install Python Virtual Environment
Create Python Virtual Environment
Install Selenium
Install Behave
Deactivate virtual env
About Python Virtual Environments
Python virtual environments are used to isolate different versions of Python projects, different versions of libraries (example, selenium lib) running at the same time in your machine. So, let’s suppose, you want to run your tests using 2 different versions of selenium (selenium_Y, selenium_Z). If we don’t have virtual environment, you would be first running your tests with selenium_Y. Once you are done, you have to override selenium_Y with selenium_Z. However with virtual environments, you don’t have to override. You can simply have 2 separate environments, one having selenium_Y, another having selenium_Z. Similarly, one virtual environment can have Python2, another can have Python3 and so on. So in each environment, we can install whatever versions or dependencies we want.
Virtual environments are especially useful for a QA, different libraries can be installed in different environments to test them out. Usage of virtual environment is optional but highly recommended.
Install Python Virtual Environment
We will now install a virtual environment for Python 3.
To get started, open the command prompt and execute below commands. These remind us about the installation paths of python and pip
You can use either of the below 2 commands to install virtual environment:
pip install virtualenv
OR
python -m pip install virtualenv
So let us execute-- python -m pip install virtualenv
The below screen shows that virtual env is already installed on my machine
However, in your case, output similar to below might be seen. This indicates that virtual env is successfully installed (see the last line)
Create Python Virtual Environment
We will now create a virtual environment for Python 3.
Run the ‘where python’ command to find out the location of python exe, see below.
We than execute below command to create a virtual env for python 3. Note that venv_py3 is the name of our virtual env. You can name it anything you wish to.
virtualenv --python="C:\Users\DELL\AppData\Local\Programs\Python\Python37-32\python.exe" venv_py3
So below is the syntax to create virtual env:
virtualenv --python="<location of python exe>" <name of virtual env>
Next, run the dir command, you will see venv_py3 directory being created
Next we will cd to this dir and then cd to Scripts dir
Next run the dir command, you would see activate.bat file
Next run the activate.bat command. Once you execute this command, you will enter inside the virtual environment, shown as rounded brackets (venv_py3)
Now when you run ‘where python’, the first one would be your virtual env
So ‘python –V’ command shows that the python ver is Python 3.7.5 as expected
Install Selenium
Execute ‘pip install selenium’ command
So selenium package/library is installed in our virtual env.
Install behave
Execute ‘pip install behave’ command
So behave package/library is installed in our virtual env, see location below
Deactivate virtual env
To deactivate our virtual env, notice below that there is a deactivate.bat file inside the Scripts directory
So just run this command, you will exit from virtual environment. You will no longer see (venv_py3)
So this is how we setup a python virtual environment. If you have another python version on your machine, you can follow the above steps to create another virtual environment!
We will continue with our setup in our next tutorial.
Thank you for reading!