Selenium Testing File Uploads in Django Admin
By Adam Vollrath
May 15, 2013
The Django framework version 1.4 added much better integration with Selenium for in-browser functional testing. This made Test-Driven Development an even more obvious decision for our new Liquid Galaxy Content Management System. This went very well until we needed to test file uploads in the Django admin interface.
A browser’s file upload control has some unique security concerns that prevent JavaScript from setting its value. Trying to do so may raise INVALID_STATE_ERR: DOM Exception 11. Selenium’s WebDriver may sometimes send keystrokes directly into the input element, but this did not work for me within Django’s admin interface.
To work around this limitation, Ryan Kelly developed a Middleware to emulate successful file uploads for automated testing. This middleware inserts additional hidden fields into any forms sent to the client. Setting their value causes a file upload to happen locally on the server. (I used a slightly newer version of this Middleware from another project.)
However, Selenium intentionally will not interact with hidden elements. To work around this, we must send JavaScript to be executed directly in the browser using WebDriver’s execute_script method.
self.browser.execute_script("document.getElementsByName('fakefile_storage')[0].value='placemark_end_point.kml'")
This is a lot of hoops to jump through, but now we have functional tests for file uploads and their post-upload processing. Hopefully the Selenium or Django projects can develop a better-supported method for file upload testing.
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