mongo/jstests/core/coveredIndex4.js

// Test covered index projection with $or clause, specifically in getMore
// SERVER-4980

t = db.jstests_coveredIndex4;
t.drop();

t.ensureIndex( { a:1 } );
t.ensureIndex( { b:1 } );

orClause = [];
for( i = 0; i < 200; ++i ) {
    if ( i % 2 == 0 ) {
        t.save( { a:i } );
        orClause.push( { a:i } );
    }
    else {
        t.save( { b:i } );
        orClause.push( { b:i } );
    }
}

c = t.find( { $or:orClause }, { _id:0, a:1 } );

// No odd values of a were saved, so we should not see any in the results.
while( c.hasNext() ) {
    o = c.next();
    if ( o.a ) {
        assert.eq( 0, o.a % 2, 'unexpected result: ' + tojson( o ) );
    }
}

c = t.find( { $or:orClause }, { _id:0, b:1 } );

// No even values of b were saved, so we should not see any in the results.
while( c.hasNext() ) {
    o = c.next();
    if ( o.b ) {
        assert.eq( 1, o.b % 2, 'unexpected result: ' + tojson( o ) );
    }
}