rack-contrib has a runtime dependency for test-spec which means that for users with rubygems greater than 1.2.0 (i.e. hopefully everyone) test-spec will be activated when the rack-contrib gem is required. It should be a development dependency like json and tmail.

I wrote a quick little Sinatra app to test JSON output, and it works fine, but when I add the Rack::ETag middleware it does not add the ETag header. I suspect the Sinatra and JSON parts of my test may be red herrings, so to speak, but it seems that JSON messes with the ETag middleware.

Context: I'm developing a Sinatra application that uses Rack::AcceptFormat to decide which handlers to execute (and so what gets sent back to the user) for an application that processes both YAML and HTML .

On my development/test machine (Ubuntu Hardy), when a request comes through which accepts text/html, the appended extension is .html

On my staging machine (Debian Lenny), the appended extension is instead .htm

The issue is here:
39 extension = Rack::Mime::MIME_TYPES.invert[accept] || @ext

MIME_TYPES has multiple keys with values of 'text/html':
[[".html", "text/html"], [".htm", "text/html"]]

When it's inverted, it seems to be pot luck as to which key ends up on top.

The situation is potentially even worse for text/plain - there are four possible extensions:
[[".log", "text/plain"], [".text", "text/plain"], [".conf", "text/plain"], [".txt", "text/plain"]]

As to how to fix - I guess the simplest behaviour would be to use a subset of Rack::Mime::MIME_TYPES that avoids conflicts. I don't have a patch, because I don't really like the solution - I just can't think of anything else that doesn't change the way this middleware works. Anyone have any other ideas?