The Lucene Test Framework is used by Lucene as the basis for its tests. The framework can also be used for testing third-party code that uses the Lucene API.

Packages 
Package Description
org.apache.lucene.analysis
Support for testing analysis components.
org.apache.lucene.analysis.standard
Classes to support StandardAnalyzer component testing
org.apache.lucene.codecs
Codecs for testing (simulate old disk formats, wacky theoretical use cases, etc)
org.apache.lucene.codecs.asserting
Codec for testing that asserts various contracts of the codec apis.
org.apache.lucene.codecs.blockterms
Codecs for testing that support org.apache.lucene.codecs.blockterms
org.apache.lucene.codecs.bloom
Support for generating test indexes using the BloomFilteringPostingsFormat
org.apache.lucene.codecs.cheapbastard
Codec that unreasonably tries to use as little RAM as possible.
org.apache.lucene.codecs.compressing
Support for testing CompressingStoredFieldsFormat.
org.apache.lucene.codecs.compressing.dummy
Dummy CompressingCodec implementation used for testing.
org.apache.lucene.codecs.cranky
Codec for testing that throws random IOExceptions
org.apache.lucene.codecs.mockrandom
Frankenstein codec for testing that pieces together random components.
org.apache.lucene.codecs.ramonly
Codec for testing that never writes to disk.
org.apache.lucene.codecs.uniformsplit
Test PostingsFormat for testing org.apache.lucene.codecs.uniformsplit with block encryption using basic ROT13.
org.apache.lucene.codecs.uniformsplit.sharedterms
Test PostingsFormat for testing org.apache.lucene.codecs.uniformsplit.sharedterms with block encryption using basic ROT13.
org.apache.lucene.geo
Reusable Geo test utilities.
org.apache.lucene.index
Support for testing of indexes.
org.apache.lucene.mockfile
Support for testing/debugging with virtual filesystems
org.apache.lucene.search
Support for testing search components.
org.apache.lucene.search.similarities
Support for testing similarities
org.apache.lucene.search.spans
Support for testing search spanqueries.
org.apache.lucene.store
Support for testing store mechanisms.
org.apache.lucene.util
General test support.
org.apache.lucene.util.automaton
Support for testing automata.
org.apache.lucene.util.fst
Support for FST testing.