view CONTRIBUTING @ 40051:cdf61ab1f54c

testing: add file storage integration for bad hashes and censoring

In order to implement these tests, we need a backdoor to write data
into storage backends while bypassing normal checks. We invent a
callable to do that.

As part of writing the tests, I found a bug with censorrevision()
pretty quickly! After calling censorrevision(), attempting to
access revision data for an affected node raises a cryptic error
related to malformed compression. This appears to be due to the
revlog not adjusting delta chains as part of censoring.

I also found a bug with regards to hash verification and revision
fulltext caching. Essentially, we cache the fulltext before hash
verification. If we look up the fulltext after a failed hash
verification, we don't get a hash verification exception. Furthermore,
the behavior of revision(raw=True) can be inconsistent depending on
the order of operations.

I'll be fixing both these bugs in subsequent commits.

Differential Revision: https://phab.mercurial-scm.org/D4865

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