[LUCENE-3995] In LuceneTestCase.beforeClass, make a new random (also using the class hashcode) to vary defaults

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0-ALPHA
• Fix Version/s: 4.0-ALPHA
• Component/s: general/test
• Lucene Fields: New
• Assignee: Dawid Weiss
• Reporter: Robert Muir
• Created: 17/Apr/12 20:28
• Updated: 28/Aug/22 13:14
• Resolved: 18/Apr/12 16:04

Description

In LuceneTestCase, we set many static defaults like:

• default codec
• default infostream impl
• default locale
• default timezone
• default similarity

Currently each test run gets a single seed for the run, which means for example across one test run
every single test will have say, SimpleText + infostream=off + Locale=german + timezone=EDT + similarity=BM25

Because of that, we lose lots of basic mixed coverage across tests, and it also means the unfortunate
individual who gets SimpleText or other slow options gets a REALLY SLOW test run, rather than amortizing
this across all test runs.

We should at least make a new random (getRandom() ^ className.hashCode()) to fix this so it works like before,
but unfortunately that only fixes it for LuceneTestCase.

Won't any subclasses that make random decisions in @BeforeClass (and we have many) still have the same problem?
Maybe RandomizedRunner can instead be improved here?

Issue Links

• relates to: LUCENE-3993 Polishing annoyances from JUnit4