Running Selenium tests from the command line on a Delivery Pipeline

5 min read

By: Paul Webster

Running Selenium tests from the command line on a Delivery Pipeline

When creating a cloud application, you often want to have automated tests for your basic UI functionality, like Selenium based tests. You can run Selenium tests through Sauce Labs or you can run them locally. However, when you run them in a Delivery Pipeline in a DevOps toolchain on IBM Bluemix, you might see errors because the server doesn’t have a way to display the browser window.

This example creates a toolchain with a pipeline job that installs a virtual display buffer that allows Firefox to display. Then the simple python example will demonstrate running Selenium tests in the Delivery Pipeline.

Running tests on a Delivery Pipeline

To run Selenium tests in Delivery Pipeline, there are 4 main steps:

  1. Install the browser and virtual display buffer.

  2. Install the Selenium drivers for your test language.

  3. Run the virtual display buffer.

  4. Run the tests.

Install the browser and virtual display buffer

Make sure your build environment includes both tools that are needed. In this example, I’m using Firefox.

  1. Install Firefox

    sudo apt-get -y --force-yes update
    sudo apt-get -y --force-yes install firefox
    firefox -v

     

  2. Install Xfvb and some supporting fonts

    sudo apt-get -y --force-yes install xvfb xfonts-100dpi \
      xfonts-75dpi xfonts-cyrillic xorg dbus-x11

     

Install the Selenium drivers for your test language

In this example, the python Selenium package uses the geckodriver to drive the Firefox browser. Both the python Selenium package and geckodriver need to be installed.

  1. Install the geckodriver

    wget https://github.com/mozilla/geckodriver/releases/download/v0.17.0/geckodriver-v0.17.0-linux64.tar.gz
    mkdir bin
    tar xvzf geckodriver-v0.17.0-linux64.tar.gz -C bin
    export PATH=$(pwd)/bin:$PATH

     

  2. Install the python package

    sudo pip install -U Selenium

Run the virtual display buffer

The virtual display buffer program allows Firefox to behave like it’s displaying on your screen. The :10indicates what screen number the virtual display runs on

Xvfb :10 -ac &
export DISPLAY=:10

Run the tests

Now you can run the tests using whatever Selenium bindings you have installed.

py.test --junitxml results.xml tests/test_python_search.py || :

Try it

You can check out an example of a toolchain that builds a python test file and runs the test by clicking the Create Toolchain button.

Create Toolchain

Troubleshooting

Scenario: None of the Selenium tests run, and you see either of these error messages:

WebDriverException: Message: The browser appears to have exited before we could connect. If you specified a log_file in the FirefoxBinary constructor, check it for details.

WebDriverException: Message: Can't load the profile. Profile Dir: %s If you specified a log_file in the FirefoxBinary constructor, check it for details.

Explanation: Your versions of Firefox and the Python Selenium driver might not be compatible. This problem is common.

Possible solution: Load either an older version of Firefox or the newest version.

  • To load an older version, enter this command:

    sudo apt-get install firefox=28.0+build2-0ubuntu2
  • To use the newest version of Firefox, enter this command:

    sudo add-apt-repository -y ppa:mozillateam/firefox-stable
    sudo apt-get -y update 

If you need to troubleshoot other issues, install a virtual machine (VM) by using a tool such as Vagrant. The Delivery Pipeline runs on Ubuntu 14.04, so a VM with that version of Ubuntu is suitable for testing and can save you time, as you won’t need to run a build every time that you want to test.

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