[LTP] [PATCH v2 2/4] doc: Update library API doc

[Petr Vorel]

about conditional expansion for TST_{SETUP,CLEANUP}.

Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
* New in v2

 doc/library-api-writing-guidelines.txt | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/doc/library-api-writing-guidelines.txt b/doc/library-api-writing-guidelines.txt
index e75c838a15..9e926e9713 100644
--- a/doc/library-api-writing-guidelines.txt
+++ b/doc/library-api-writing-guidelines.txt
@@ -61,3 +61,23 @@ API source code is in 'tst_test.sh', 'tst_security.sh' and 'tst_net.sh'
 
 Changes in the shell API should not introduce uncommon dependencies
 (use basic commands installed everywhere by default).
+
+3.1 Shell libraries
+~~~~~~~~~~~~~~~~~~~
+
+Besides shell API libraries in 'testcases/lib' it's worth to put common code
+for particular tests into shell library. The filename should end '_lib.sh',
+they should load 'tst_test.sh' or 'tst_net.sh'.
+
+Shell libraries should have conditional expansion for 'TST_SETUP' or 'TST_CLEANUP',
+to avoid surprises when test specific setup/cleanup function is redefined by
+shell library.
+
+[source,sh]
+-------------------------------------------------------------------------------
+# ipsec_lib.sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+TST_SETUP=${TST_SETUP:-ipsec_lib_setup}
+. tst_test.sh
+...
+-------------------------------------------------------------------------------
-- 
2.35.3