py_virtual_envs.py

from seleniumbase import BaseCase
BaseCase.main(__name__, __file__)


class PythonVirtualEnvs(BaseCase):
    def test_py_virtual_envs(self):
        self.create_presentation(theme="serif", transition="slide")
        self.add_slide(
            "<h2>Python Virtual Environments:</h2><br />\n"
            "<h2>What, Why, and How</h2><hr /><br />\n"
            "<h3>Presented by <b>Michael Mintz</b></h3>\n"
            "<p>Granite State Code Camp - Sat, Nov 14, 2020</p>"
        )
        self.add_slide(
            "<p><b>About me:</b></p>\n"
            "<ul>"
            "<li>I created the <b>SeleniumBase</b> framework.</li>"
            "<li>I'm currently the DevOps Lead at <b>iboss</b>.</li>"
            "</ul>\n",
            image="https://seleniumbase.io/other/iboss_booth.png",
        )
        self.add_slide(
            "<p><b>Topics & tools covered by this presentation:</b></p>"
            "<hr /><br />\n"
            "<ul>"
            "<li>Overview of Virtual Environments</li>"
            "<li>Python package management</li>"
            '<li>Python 3 "venv"</li>'
            "<li>virtualenv / virtualenvwrapper</li>"
            '<li>pip / "pip install"</li>'
            "<li>requirements.txt files</li>"
            "<li>setup.py files</li>"
            "</ul>"
        )
        self.add_slide(
            "<p><b>Topics & tools that are NOT covered here:</b></p><hr />\n"
            "<br /><div><ul>"
            '<li>"conda"</li>'
            '<li>"pipenv"</li>'
            '<li>"poetry"</li>'
            '<li>"pipx"</li>'
            "</ul></div><br />"
            "<p>(Other Python package management tools)</p>"
        )
        self.add_slide(
            "<p><b>What is a Python virtual environment?</b></p><hr /><br />\n"
            "<p>A Python virtual environment is a partitioned directory"
            " where a Python interpreter, libraries/packages, and scripts"
            " can be installed and isolated from those installed in other"
            " virtual environments or the global environment.</p>"
        )
        self.add_slide(
            "<p><b>Why should we use Python virtual environments?</b>"
            "</p><hr /><br />\n"
            "<p>We should use Python virtual environments because different"
            " Python projects can have conflicting Python dependencies that"
            " cannot coexist in the same env.</p>"
        )
        self.add_slide(
            "<p><b>Why? - continued</b></p><hr /><br />\n"
            "<p>Example: Project A and Project B both depend on"
            " different versions of the same Python library!</p>"
            "<p>Therefore, installing the second project requirements"
            " would overwrite the first one, causing it to break.</p>",
            code=(
                "# Project A requirement:\n"
                "urllib3==1.25.3\n\n"
                "# Project B requirement:\n"
                "urllib3==1.26.2"
            ),
        )
        self.add_slide(
            "<p><b>Why? - continued</b></p><hr /><br />\n"
            "<p>It is also possible that Project A and Project B"
            " require different versions of Python installed!</p>",
            code=(
                "# Project A requirement:\n"
                "Python-3.8\n\n"
                "# Project B requirement:\n"
                "Python-2.7"
            ),
        )
        self.add_slide(
            "<p><b>How do we create and use Python virtual envs?</b>"
            "</p><hr /><br />\n"
            "<div><b>There are tools/scripts we can use:</b></div><br />"
            "<ul>"
            '<li>The Python 3 "venv" command</li>'
            "<li>virtualenv / virtualenvwrapper</li>"
            "</ul>"
        )
        self.add_slide(
            '<p><b>Python 3 "venv"</b></p><hr /><br />\n'
            '"venv" creates virtual environments in the location where run'
            " (generally with Python projects).",
            code=(
                "# Mac / Linux\n"
                "python3 -m venv ENV_NAME\n"
                "source ENV_NAME/bin/activate\n\n"
                "# Windows\n"
                "py -m venv ENV_NAME\n"
                "call ENV_NAME\\Scripts\\activate\n\n"
                '# (Type "deactivate" to leave a virtual environment.)'
            ),
        )
        self.add_slide(
            '<p><b>"mkvirtualenv" (from virtualenvwrapper)</b></p><hr />\n'
            '<br />"mkvirtualenv" creates virtual environments in one place'
            " (generally in your home directory).",
            code=(
                "# Mac / Linux\n"
                "python3 -m pip install virtualenvwrapper\n"
                "export WORKON_HOME=$HOME/.virtualenvs\n"
                "source `which virtualenvwrapper.sh`\n"
                "mkvirtualenv ENV_NAME\n\n"
                "# Windows\n"
                "py -m pip install virtualenvwrapper-win\n"
                "mkvirtualenv ENV_NAME\n\n"
                '# (Type "deactivate" to leave a virtual environment.)'
            ),
        )
        self.add_slide(
            "<p><b>List of commands from virtualenvwrapper</b></p>"
            "<hr /><br />",
            code=(
                "# Create a virtual environment:\n"
                "mkvirtualenv ENV_NAME\n\n"
                "# Exit your virtual environment:\n"
                "deactivate\n\n"
                "# Re-enter a virtual environment:\n"
                "workon ENV_NAME\n\n"
                "# List all virtual environments:\n"
                "workon\n\n"
                "# Delete a virtual environment:\n"
                "rmvirtualenv ENV_NAME"
            ),
        )
        self.add_slide(
            "<p><b>Determining if you are in a virtual env</b></p>"
            "<hr /><br />"
            "<p>When activated, the name of your virtual env"
            " will appear in parentheses on the left side of your"
            " command prompt.</p>",
            code=(
                "# Example of how it may look on a Windows machine:\n"
                "C:\\Users\\Michael\\github> mkvirtualenv my_env\n"
                "(my_env)  C:\\Users\\Michael\\github>"
            ),
        )
        self.add_slide(
            '<p><b>Installing packages with "pip install"</b></p><hr /><br />'
            "<p>Once you have created a Python virtual environment and are"
            " inside, it is now safe to install packages from PyPI,"
            " setup.py files, and/or requirements.txt files.</p>\n",
            code=(
                "# Install a package from PyPI:\n"
                "pip install seleniumbase\n\n"
                "# Install packages from a folder with setup.py:\n"
                "pip install .  # Normal installation\n"
                "pip install -e .  # Editable install\n\n"
                "# Install packages from a requirements.txt file:\n"
                "pip install -r requirements.txt\n"
            ),
        )
        self.add_slide(
            '<p><b>Other useful "pip" commands</b></p><hr /><br />',
            code=(
                "# See which Python packages are installed:\n"
                "pip list\n\n"
                "# See which installed Python packages are outdated:\n"
                "pip list --outdated\n\n"
                "# Create a requirements file from installed packages:\n"
                "pip freeze > my_requirements.txt"
            ),
        )
        self.add_slide(
            "<br /><br /><h2><b>Live Demo Time!</b></h2><hr /><br />",
            image="https://seleniumbase.io/other/python_3d_logo.png",
        )
        self.add_slide(
            "<h2><b>The End. Questions?</b></h2><hr /><br />\n"
            "<h3>Where to find me:</h3>"
            "<ul>"
            '<li><a href="https://github.com/mdmintz">'
            "github.com/mdmintz</a></li>"
            '<li><a href="https://github.com/seleniumbase/SeleniumBase">'
            "github.com/seleniumbase/SeleniumBase</a></li>"
            '<li><a href="https://seleniumbase.io/">'
            "seleniumbase.io</a></li>"
            "</ul>"
        )
        self.begin_presentation(
            filename="py_virtual_envs.html", show_notes=False, interval=0
        )