mongo/jstests/core/query/array/arrayfind9.js

// Assorted $elemMatch behavior checks.
// @tags: [
//   requires_getmore
// ]

let t = db.jstests_arrayfind9;
t.drop();

// Top level field $elemMatch:$not matching
t.save({a: [1]});
assert.eq(1, t.count({a: {$elemMatch: {$not: {$ne: 1}}}}));

// Top level field object $elemMatch matching.
t.drop();
t.save({a: [{}]});
assert.eq(1, t.count({a: {$elemMatch: {$gte: {}}}}));

// Top level field array $elemMatch matching.
t.drop();
t.save({a: [[]]});
assert.eq(1, t.count({a: {$elemMatch: {$in: [[]]}}}));

// Matching by array index.
t.drop();
t.save({a: [["x"]]});
assert.eq(1, t.count({a: {$elemMatch: {"0": "x"}}}));

// Matching multiple values of a nested array.
t.drop();
t.save({a: [{b: [0, 2]}]});
t.createIndex({a: 1});
t.createIndex({"a.b": 1});
let plans = [{$natural: 1}, {a: 1}, {"a.b": 1}];
for (let i in plans) {
    let p = plans[i];
    assert.eq(
        1,
        t
            .find({a: {$elemMatch: {b: {$gte: 1, $lte: 1}}}})
            .hint(p)
            .itcount(),
    );
}