Over the past 30 days or so, the acceptance test project has made a great progress.
This project consists of a reusable harness that can be used by plugin developers and users to write functional test cases. These tests can be run against Jenkins instances that are deployed in all sorts of different ways, and can interact with complex real fixtures. These tests can be also run with specific version of Jenkins core and a combination of plugins.
The number of tests have steadily increased to above 300. Several of those are by Michael Prankl, where he tests the LDAP plugin with the real OpenLDAP server instance that runs inside Docker — a kind of test that just wasn't possible before can be now easily written.