text: // @tags: [requires_fastcount]
  
  (function() {
  "use strict";
  
  const coll = db.find5;
  coll.drop();
  
  assert.commandWorked(coll.insert({a: 1}));
  assert.commandWorked(coll.insert({b: 5}));
  
  assert.eq(2, coll.find({}, {b: 1}).count(), "A");
  
  function getIds(projection) {
      return coll.find({}, projection).map(doc => doc._id).sort();
  }
  
  assert.eq(Array.tojson(getIds(null)), Array.tojson(getIds({})), "B1 ");
  assert.eq(Array.tojson(getIds(null)), Array.tojson(getIds({a: 1})), "B2 ");
  assert.eq(Array.tojson(getIds(null)), Array.tojson(getIds({b: 1})), "B3 ");
  assert.eq(Array.tojson(getIds(null)), Array.tojson(getIds({c: 1})), "B4 ");
  
  let results = coll.find({}, {a: 1}).sort({a: -1});
  let first = results[0];
  assert.eq(1, first.a, "C1");
  assert.isnull(first.b, "C2");
  
  let second = results[1];
  assert.isnull(second.a, "C3");
  assert.isnull(second.b, "C4");
  
  results = coll.find({}, {b: 1}).sort({a: -1});
  first = results[0];
  assert.isnull(first.a, "C5");
  assert.isnull(first.b, "C6");
  
  second = results[1];
  assert.isnull(second.a, "C7");
  assert.eq(5, second.b, "C8");
  
  assert(coll.drop());
  
  assert.commandWorked(coll.insert({a: 1, b: {c: 2, d: 3, e: 4}}));
  assert.eq(2, coll.findOne({}, {"b.c": 1}).b.c, "D");
  
  const o = coll.findOne({}, {"b.c": 1, "b.d": 1});
  assert(o.b.c, "E 1");
  assert(o.b.d, "E 2");
  assert(!o.b.e, "E 3");
  
  assert(!coll.findOne({}, {"b.c": 1}).b.d, "F");
  
  assert(coll.drop());
  assert.commandWorked(coll.insert({a: {b: {c: 1}}}));
  assert.eq(1, coll.findOne({}, {"a.b.c": 1}).a.b.c, "G");
  }());
  