t = db.embeddedIndexTest;

t.remove({});

o = {
    name: "foo",
    z: {a: 17, b: 4}
};
t.save(o);

assert(t.findOne().z.a == 17);
assert(t.findOne({z: {a: 17}}) == null);

t.ensureIndex({"z.a": 1});

assert(t.findOne().z.a == 17);
assert(t.findOne({z: {a: 17}}) == null);

o = {
    name: "bar",
    z: {a: 18}
};
t.save(o);

assert.eq.automsg("2", "t.find().length()");
assert.eq.automsg("2", "t.find().sort( { 'z.a' : 1 } ).length()");
assert.eq.automsg("2", "t.find().sort( { 'z.a' : -1 } ).length()");

assert(t.validate().valid);