PhraseQuery.Builder builder = new PhraseQuery.Builder();
        PhraseQuery phraseQuery = builder.build();
        QueryContext context = new QueryContext("test", false);

        try {
            queryCommand.convertPhraseQuery(context, phraseQuery, 1.0f);
            fail("Should throw InvalidQueryException for empty phrase query");
        } catch (InvalidQueryException e) {
            assertTrue(e.getMessage().contains("Unknown phrase query"));