LUCENENET specific. Ensure we have an infostream attached to the default FieldCache when running the tests. In Java, this was done in the Core.Search.TestFieldCache.TestInfoStream() method (which polluted the state of these tests), but we need to make the tests self-contained so they can be run correctly regardless of order. Not setting the InfoStream skips an execution path within these tests, so we should do it to make sure we test all of the code.