@AfterEach
    final void teardown() throws IOException {
        teardown(dbDir1, lmdbEnv1);
        lmdbEnv1 = null;
        teardown(dbDir2, lmdbEnv2);
        lmdbEnv2 = null;
    }
Useful for comparing the behaviour of two different envs
stroom-lmdb/src/test/java/stroom/lmdb/AbstractDualEnvLmdbTest.java