JiraFa (derived from "Jira Finder") is a Jenkins plugin that is extension of JUnit Jenkins plugin. Its goal is to save you as much time as possible during evaluation of functional tests results.
JiraFa needs a persistent storage in Jenkins for storing the associations test failure <--> JIRA issue. It uses a database for it, hence you need to configure it in the main Jenkins configuration.
Now that you have global configuration done, you need to enable and configure JiraFa for the job, that you want to use it with.
Now you're ready to start working with JiraFa.
When executed a job, tests produce JUnit report, which you can see in "Test result" windows on build detail page. JiraFa will automatically mark test failures either known or unknown, meaning "known" are those failures that have no issue linked to it.
If you click the "+" sign next to test failure, JiraFa will show you "Found issues" that it found in the JIRA related to this test failure. You can link the JIRA to the failure making it known and it will appear next time it fails as known failure.
JiraFa searches for package.test_name.method_name, package.test_name and test_name.method_name. If JiraFa is not able to find corresponding JIRA, just edit the description of the JIRA or add a comment to it with the test failure, JIRA will be then able to find it.