// SERVER-4638 - this tests explicit undefined values
// This case is marked as a dup of SERVER-4674

t = db.server4638
t.drop();

t.insert( { _id : 0 , x : 0 , undef: undefined } );

// Make sure having an undefined doesn't break pipelines not using the field
res = t.aggregate( { $project : { x : 1 } } ).toArray();
assert.eq(res[0].x, 0);


// Make sure having an undefined doesn't break pipelines that do use the field
res = t.aggregate( { $project : { undef : 1 } } ).toArray();
assert.eq(res[0].undef, undefined);
assert.eq(typeof(res[0].undef), "undefined");