test_ipmi_user_robot: skip instead of fail test for short pasword.

Skip 'Verify IPMI Root User Password Change' if len(OPENBMC_PASSWORD) < 8
Aspects:
- Graceful exit (skip instead of fail) for short OPENBMC_PASSWORD.
- Add comment to clarify reason: password < 8 chars cannot be set,
  thus the restore password step in Teardown would fail.
- This affects "out-of-the-box" operation with default password 0penBmc.
- Evaluate precondition in Setup step.  Skip if precondition violated.
- Make restoring pw in Teardown conditional on 'TEST STATUS' != 'SKIP'.
- For clarity, rename keyword: 'Set Default Password For IPMI Root User'
  -> 'Restore Default Password For IPMI Root User'

Tested: operates as intended with both a 7-char pw and a 15-char pw.

Signed-off-by: Ruud A. Haring <ruud@us.ibm.com>
Change-Id: If3b67e9479824e5c6b6b95df366887e0af5a7cd3
diff --git a/ipmi/test_ipmi_user.robot b/ipmi/test_ipmi_user.robot
index 32f1db3..7d913e3 100644
--- a/ipmi/test_ipmi_user.robot
+++ b/ipmi/test_ipmi_user.robot
@@ -339,12 +339,15 @@
     [Documentation]  Change IPMI root user password and verify that
     ...  root user is able to run IPMI command.
     [Tags]  Verify_IPMI_Root_User_Password_Change
+    [Setup]  Skip if  len( '${OPENBMC_PASSWORD}' ) < 8
+    ...  msg= Do not run this test if len( OPENBMC_PASSWORD ) < 8
+    # Reason: if OPENBMC_PASSWORD is not at least 8 characters,
+    #         it cannot be restored in the Teardown step.
     [Teardown]  Run Keywords  FFDC On Test Case Fail  AND
+    ...  Run Keyword If  "${TEST STATUS}" != "SKIP"
     ...  Wait Until Keyword Succeeds  15 sec  5 sec
-    ...  Set Default Password For IPMI Root User
+    ...  Restore Default Password For IPMI Root User
 
-    # User input password should be minimum 8 characters long.
-    Valid Length  OPENBMC_PASSWORD  min_length=8
     # Set new password for root user.
     Run IPMI Standard Command
     ...  user set password ${root_userid} ${valid_password}
@@ -511,9 +514,9 @@
 
 *** Keywords ***
 
-Set Default Password For IPMI Root User
-    [Documentation]  Set default password for IPMI root user (i.e. 0penBmc).
-    # Set default password for root user.
+Restore Default Password For IPMI Root User
+    [Documentation]  Restore default password for IPMI root user
+
     ${result}=  Run External IPMI Standard Command
     ...  user set password ${root_userid} ${OPENBMC_PASSWORD}
     ...  P=${valid_password}