Hello Tibor Kiss. Steve is referring to this policy in the Hadoop contribution wiki:
To summarize, for modules like hadoop-azure, hadoop-aws, etc., there are either no unit tests running during Apache pre-commit, or there are unit tests in the module, but we consider them insufficient to validate a patch for commit. Instead, we require the contributor to run integration tests directly against the back-end service. These are still structured as JUnit tests under the src/test/java directory, but the tests get skipped unless the developer does some extra configuration to make the necessary credentials available. The exact configuration process varies per file system:
For this patch, I'm going to kick off my own test run for you now. We currently have a test failure on branch-2 and branch-2.8 because of this, so I want to get it fixed quickly. You can keep this information in mind for future patches though.