Impact of Patch can be analyzed in two ways
1) Using Patch Wizard functionality which is available from System Administrator responsibility under OAM > Patching and Utilities
2) adpatch utility
There are 3 modes of applying the patch.
1) Pre-Install Mode
2) Test Mode
3) Non-Interactive Mode
It’s always good to run the patch in test mode and analyze the things before applying the patch in normal mode. When running the patch in test mode, it tells us everything it would have done in applying a patch, but doesn’t actually apply the patch.
To run AutoPatch in Test Mode, we must include ‘apply=no’ on the AutoPatch command line. For example:
$ adpatch apply=no
After running this command, it will ask you for log file name which will be stroed in $APPL_TOP/admin/ directory. This log file will list out all the files which will be applied or not applied.
Below are the steps to identify logical changes applied by the patch. Once you identify the change being applied by patch, you can create test scenarios out of it
1) Look at the "list of bugs fixed" section in the README file for the patch
2) Run below query, which will tell you the list of bugs already applied. Remaining list of bugs are the actual ones which will be applied by patch as a logical change. You can then create test cases and scenarios by studying this bugs
SELECT bug_number, creation_date
WHERE bug_number in (list of bug numbers from README file in step-1)