[[Testing]]
= Testing Filesystem Changes

People put a lot of trust in filesystems to preserve their data in a reliable
fashion.  To that end, it is very important that users and developers have
access to a suite of regression tests that can be used to prove correct
operation of any given filesystem code, or to analyze failures to fix problems
found in the code.  The XFS regression test suite, +xfstests+, is hosted at
+git://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git+.  Most tests apply to
filesystems in general, but the suite also contains tests for features specific
to each filesystem.

When fixing bugs, it is important to provide a testcase exposing the bug so
that the developers can avoid a future re-occurrence of the regression.
Furthermore, if you're developing a new user-visible feature for XFS, please
help the rest of the development community to sustain and maintain the whole
codebase by providing generous test coverage to check its behavior.

When altering, adding, or removing an on-disk data structure, please remember
to update both the in-kernel structure size checks in +xfs_ondisk.h+ and to
ensure that your changes are reflected in xfstest xfs/122.  These regression
tests enable us to detect compiler bugs, alignment problems, and anything
else that might result in the creation of incompatible filesystem images.