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[1/2] docs: Describe using images in writing iotests

Message ID 20180724084739.580-2-famz@redhat.com
State New
Headers show
Series iotests: Fix 226 on _my_ system | expand

Commit Message

Fam Zheng July 24, 2018, 8:47 a.m. UTC
Signed-off-by: Fam Zheng <famz@redhat.com>
 docs/devel/testing.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)
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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
+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