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authorFam Zheng <famz@redhat.com>2018-07-24 16:47:38 +0800
committerKevin Wolf <kwolf@redhat.com>2018-07-30 15:35:37 +0200
commitf4a1b6536f70d33caa9da6c091b98038943998c9 (patch)
tree23d33c0c7a527b577ca09f3d3f1dd874e79996a8
parenta1c81f4f16a74d0d544f5d3ac405bcaad83541fd (diff)
docs: Describe using images in writing iotests
Signed-off-by: Fam Zheng <famz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--docs/devel/testing.rst11
1 files changed, 11 insertions, 0 deletions
diff --git a/docs/devel/testing.rst b/docs/devel/testing.rst
index 5e19cd50da..8e1fa3a66e 100644
--- a/docs/devel/testing.rst
+++ b/docs/devel/testing.rst
@@ -255,6 +255,17 @@ comparable library support for invoking and interacting with QEMU programs. If
you opt for Python, it is strongly recommended to write Python 3 compatible
code.
+Both Python and Bash frameworks in iotests provide helpers to manage test
+images. They can be used to create and clean up images under the test
+directory. If no I/O or any protocol specific feature is needed, it is often
+more convenient to use the pseudo block driver, ``null-co://``, as the test
+image, which doesn't require image creation or cleaning up. Avoid system-wide
+devices or files whenever possible, such as ``/dev/null`` or ``/dev/zero``.
+Otherwise, image locking implications have to be considered. For example,
+another application on the host may have locked the file, possibly leading to a
+test failure. If using such devices are explicitly desired, consider adding
+``locking=off`` option to disable image locking.
+
Docker based tests
==================