mongo/jstests/core/query/array/arrayfind5.js

// Test indexed elemmatch of missing field.

let t = db.jstests_arrayfind5;
t.drop();

function check(nullElemMatch) {
    assert.eq(1, t.find({'a.b': 1}).itcount());
    assert.eq(1, t.find({a: {$elemMatch: {b: 1}}}).itcount());
    assert.eq(nullElemMatch ? 1 : 0, t.find({'a.b': null}).itcount());
    assert.eq(nullElemMatch ? 1 : 0,
              t.find({a: {$elemMatch: {b: null}}}).itcount());  // see SERVER-3377
}

t.save({a: [{}, {b: 1}]});
check(true);
t.createIndex({'a.b': 1});
check(true);

t.drop();

t.save({a: [5, {b: 1}]});
check(false);
t.createIndex({'a.b': 1});
check(false);