To do this, the following steps should help: 1. add `.ftl` to the list at https://searchfox.org/mozilla-central/rev/0ee0b63732d35d16ba22d5a1120622e2e8d58c29/browser/base/content/test/static/browser_all_files_referenced.js#600 . Probably worth indenting the list a bit nicer while we're there instead of having such a long line. (You could just run the test as a sanity check after this step - I'd expect it to flag up every single packaged .ftl file we have.) 2. add a block to `parseCodeFile` that checks for .ftl paths. That is, somewhere in this loop that does per-line checks: https://searchfox.org/mozilla-central/rev/0ee0b63732d35d16ba22d5a1120622e2e8d58c29/browser/base/content/test/static/browser_all_files_referenced.js#404 we need to add a regular expression looking for `/[a-z0-9_\/-]+\.ftl/i`, and set `urls` to an array of any found string, prefixed with "resource:///localization/en-US/". (or maybe `resource://app/localization/en-US/`, I'm not 100% sure) 3. Test, and add any unreferenced .ftl files to the list of exceptions at the top of the file. Note that in theory, there shouldn't be any unreferenced ftl files. I haven't tested this plan. I'm fairly confident that it's correct in the rough steps, but you'll probably run into issues which you'll need to debug. You can use the `info` helper function to log things (`info("Hello from the test")`). You can also add a `debugger;` statement in the JS and run the test as `./mach mochitest browser/base/content/test/static/browser_all_files_referenced.js --jsdebugger` . It'll break into the debugger when it hits the `debugger;` statement, at which point you can inspect variables etc. One more point of note is that after getting this to work, you'll need to also check that it works against a packaged build, which is what the test will run against on our test infrastructure. You can do this locally by first running: ./mach package and then running the test using: ./mach mochitest browser/base/content/test/static/browser_all_files_referenced.js --appname=dist to run against the packaged 'dist' build.

Pushed by gijskruitbosch@gmail.com: https://hg.mozilla.org/integration/autoland/rev/777d4b26e0b1 Checking if all shipped fluent files are referenced, r=Gijs