t = db.find4;
t.drop();

t.save({a: 1123, b: 54332});

o = t.find({}, {})[0];
assert.eq(1123, o.a, "A");
assert.eq(54332, o.b, "B");
assert(o._id.str, "C");

o = t.find({}, {a: 1})[0];
assert.eq(1123, o.a, "D");
assert(o._id.str, "E");
assert(!o.b, "F");

o = t.find({}, {b: 1})[0];
assert.eq(54332, o.b, "G");
assert(o._id.str, "H");
assert(!o.a, "I");

t.drop();
t.save({a: 1, b: 1});
t.save({a: 2, b: 2});
assert.eq("1-1,2-2",
          t.find()
              .map(function(z) {
                  return z.a + "-" + z.b;
              })
              .toString());
assert.eq("1-undefined,2-undefined",
          t.find({}, {a: 1})
              .map(function(z) {
                  return z.a + "-" + z.b;
              })
              .toString());