# Selenium Atoms

Marionette uses a small list of [Selenium atoms] to interact with web elements.
Initially those have been added to ensure a better reliablity due to a wider usage
inside the Selenium project. But by adding full support for the [WebDriver
specification] they will be removed step by step.

Currently the following atoms are in use:

* clearElement
* getText
* isDisplayed
* isEnabled
* isSelected

To use one of those atoms Javascript modules will have to import [atom.js].

[Selenium atoms]: https://github.com/SeleniumHQ/selenium/tree/master/javascript/webdriver/atoms
[WebDriver specification]: https://w3c.github.io/webdriver/webdriver-spec.html
[atom.js]: ../atom.js


## Update required Selenium Atoms

In regular intervals the atoms, which are still in use, have to be updated.
Therefore they have to be exported from the Selenium repository first, and then
updated in [atom.js].

### Export Selenium Atoms

The canonical GitHub repository for Selenium is

    https://github.com/SeleniumHQ/selenium.git

so make sure to have a local copy of it. For the cloning process it is
recommended to specify the `--depth=1` argument, so only the last changeset is
getting downloaded (which itself will already be more than 100 MB). Once the
clone is ready the export of the atoms can be triggered by running the following
commands:

    % cd selenium
    % ./go
    % python buck-out/crazy-fun/%changeset%/buck.pex build --show-output %atom%

Hereby `%changeset%` corresponds to the currently used version of buck, and
`%atom%` to the atom to export. The following targets for exporting are available:

* //javascript/webdriver/atoms:clear-element-firefox
* //javascript/webdriver/atoms:get-text-firefox
* //javascript/webdriver/atoms:is-displayed-firefox
* //javascript/webdriver/atoms:is-enabled-firefox
* //javascript/webdriver/atoms:is-selected-firefox

For each of the exported atoms a file can now be found in the folder
`buck-out/gen/javascript/webdriver/atoms/`. They contain all the code including
dependencies for the atom wrapped into a single function.

### Update atom.js

To update the atoms for Marionette the `atoms.js` file has to be edited. For
each atom to be updated the steps as layed out below have to be performed:

1. Open the Javascript file of the exported atom. See above for its location.
2. Remove the contained license header, which can be found somewhere in the
   middle of the file.
3. Update the parameters of the wrapper function (at the very top) so that those
   are equal with the used parameters in `atom.js`.
4. Copy the whole content of the file, and replace the existing code for the atom
   in `atom.js`.

### Test the changes

To ensure that the update of the atoms doesn't cause a regression a try build
should be run including Marionette unit tests, Firefox ui tests, and all the
web-platform-tests.