zope.testbrowser truncates document content after goBack()

I can confirm that. It is probably a mechanize issue. I avoid the issue by doing reload(). ;-)

Changes: submitter email, importance (medium => critical)

I think I found the bug:

* mechanize.Browser closes self._response and stashes it in its history list before opening a new page.

* self._response is ClientCookie._Util.response_seek_wrapper that wraps urllib.addinfourl that wraps socket._fileobject that wraps something (httplib.HTTPResponse perhaps?).

* response_seek_wrapper has a cache (a StringIO) that is stuffed with data read from the wrapped stream, so it can be re-read.

* response_seek_wrapper.close() closes the wrapped stream, and subsequent reads from that response_seek_wrapper read only the data that is already in the cache.

* hence truncation.

I added three lines to response_seek_wrapper.close():

            pos = self.tell()
            self.seek(0, 2)
            self.seek(pos)

just before it calls self.wrapper.close().

This fixes the problem for me

I'll leave it to someone more knowledgeable to decide whether this is the
proper fix and should be pushed into ClientCookie.

In the meantime a workaround is to do

   >>> whatever = len(browser.contents)

if you want to browser.goBack() to this page at some latter point

Changes: edited transcript, revised title

This was fixed in revision 68784 by upgrading mechanize and can be resolved.

Status: Pending => Resolved

LP suffered this but worked around at the time; I'm sure we've updated zope.testbrowser since - and if not we're clearly not suffering now:)