// confirm that undefined no longer counts as 0 in $avg
c = db.c;
c.drop();
c.save({a: 1});
c.save({a: 4});
c.save({b: 1});
assert.eq(c.aggregate({$group: {_id: null, avg: {$avg: "$a"}}}).toArray()[0].avg, 2.5);

// again ensuring numberLongs work properly
c.drop();
c.save({a: NumberLong(1)});
c.save({a: NumberLong(4)});
c.save({b: NumberLong(1)});
assert.eq(c.aggregate({$group: {_id: null, avg: {$avg: "$a"}}}).toArray()[0].avg, 2.5);