How to install py.test?

Question

So I am new to Python. This may be a very foolish question, but I have no idea how to install packages as pytest?

It would be great if somebody could give instructions in order to achieve this.

Gump

Please specify the OS – Fossick

I am running windows 8 with python 3.3. – Gump

Answer 1

In general, installing a package in Python is pretty simple if you use pip which is already installed if you're using Python 2 >=2.7.9 or Python 3 >=3.4.

In order to install pytest:

Python 2: $ pip install pytest

Python 3: $ pip3 install pytest

However, it is a good practice to isolate Python environments by creating a virtual environment. In order to install pytest in an isolated virtual environment:

Python 2

$ pip install -U virtualenv
$ python -m virtualenv venv
$ source venv/bin/activate # in Windows -> $ venv\Scripts\activate.bat
$ pip install pytest

Python 3

$ pip3 install -U virtualenv
$ python3 -m virtualenv venv
$ source venv/bin/activate # in Windows -> $ venv\Scripts\activate.bat
$ pip install pytest

Python 3.6+

$ python3 -m venv venv
$ source venv/bin/activate # in Windows -> $ venv\Scripts\activate.bat
$ pip install pytest

Comatose

Is it a trick to use specific pytest default version? I'm under Debian-Jessie-like distro, so python 2.7 is default. If I creates a venv with python3.6 -m venv .venv, and install pytest after activate this venv with pip install pytest==3.7.1, the version called by pytest --version is This is pytest version 3.2.1 imported from /usr/local/lib/python2.7/dist-packages/pytest.pyc setuptools registered plugins , if I want to use the newly installed version I have to call python -m pytest --version. If this need a dedicated question, I'll do. – Durance

@freezed, if your default version is Python 2, then you have first to install Python 3. Or you should use pip install -U virtualenv to install a virtual environment using python 2. What is the output you are getting after activating your virtual environment if you run which python, and what is the output you get when you run which pip (again after activating the virtual environment). – Comatose

Here is paths of python in/outside venv. Here is a screenshot of my troubles… but today, I cannot reproduce this behavior… pytest in venv corresponds to the venv python branch… I put this on side, I will see if it happens again. Thanks for answering. – Durance

Answer 2

Maybe you're looking for something like pip.

For example, if you want to install Cherrypy you must to run

    pip install cherrypy

or if you're using python3, and depending of your distro, the command is

    pip3 install cherrypy

If you're downloading a package from source, then you must to uncompress it and normally, depending the package, you must to run (as administrator or root)

    python setup.py install

Parmentier

Suggesting to use pip with sudo is not a great idea and should only be done with care. – Impassable

What exactly is "with care"? – Maulmain