mongo/jstests/core/cursor2.js

/**
 *  test to see if the count returned from the cursor is the number of objects that would be
 *returned
 *
 *  BUG 884
 */
function testCursorCountVsArrLen(dbConn) {
    var coll = dbConn.ed_db_cursor2_ccvsal;

    coll.drop();

    coll.save({a: 1, b: 1});
    coll.save({a: 2, b: 1});
    coll.save({a: 3});

    var fromCount = coll.find({}, {b: 1}).count();
    var fromArrLen = coll.find({}, {b: 1}).toArray().length;

    assert(fromCount == fromArrLen,
           "count from cursor [" + fromCount + "] !=  count from arrlen [" + fromArrLen + "]");
}

testCursorCountVsArrLen(db);