// SERVER-6177: better error when projecting into a subfield with an existing expression

// load the test utilities
load('jstests/aggregation/extras/utils.js');

var c = db.c;
c.drop();

c.save( {} );

// These currently give different errors
assertErrorCode(c, { $project:{ 'x':{ $add:[ 1 ] }, 'x.b':1 } }, 16401);
assertErrorCode(c, { $project:{ 'x.b': 1, 'x':{ $add:[ 1 ] }} }, 16400);

// These both give the same error however
assertErrorCode(c, { $project:{'x':{'b':1}, 'x.b': 1} }, 16400);
assertErrorCode(c, { $project:{'x.b': 1, 'x':{'b':1}} }, 16400);