[LUCENE-3565] StandardQueryParser generates incorrect query for groups containing one term if using default operator AND

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 3.4
• Component/s: modules/queryparser
• Labels: queryparser
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Trejkaz
• Created: 06/Nov/11 21:47
• Updated: 28/Aug/22 13:01
• Resolved: 22/Jan/14 04:21

Description

The following test demonstrates a bug in StandardQueryParser when DEFAULT_OPERATOR is set to AND:

    @Test
    public void testDefaultOperatorSingleGrouped() throws Exception
    {
        StandardQueryParser parser = new StandardQueryParser();
        parser.getQueryConfigHandler().set(StandardQueryConfigHandler.ConfigurationKeys.DEFAULT_OPERATOR, StandardQueryConfigHandler.Operator.AND);

        BooleanQuery expectedQuery = new BooleanQuery();
        BooleanQuery innerQuery1 = new BooleanQuery();
        innerQuery1.add(new TermQuery(new Term("text", "a")), BooleanClause.Occur.MUST);
        expectedQuery.add(innerQuery1, BooleanClause.Occur.SHOULD);
        BooleanQuery innerQuery2 = new BooleanQuery();
        innerQuery2.add(new TermQuery(new Term("text", "b")), BooleanClause.Occur.MUST);
        expectedQuery.add(innerQuery2, BooleanClause.Occur.SHOULD);
        Query actualQuery = parser.parse("(a) OR (b)", "text");

        assertEquals("Wrong query was generated", expectedQuery, actualQuery);
    }

BooleanSingleChildOptimizationQueryNodeProcessor appears to be responsible because if I remove it, the correct query is generated (however, doing so breaks a number of other tests of our own.)