On the desktop, we can test our extension by loading its unpacked files into Firefox Developer Edition and automating it with Selenium (driven by wdio).
Our continuous integration needs to do the same thing but in Docker.
Selenium provide a handy Docker image with standard Firefox but they are not interested in providing one with Developer Edition.
To use standard Firefox, we would need a signed extension (the standard build no longer lets you disable the requirement for signing). We used to sign test builds of the extension but now there is a danger that Mozilla will decide to review it, which is a waste of their time for test builds (and for which they require us to supply source code somehow).
Is anyone else testing an extension with Selenium in Docker?