mongo/jstests/core/query/update/update_arraymatch7.js

// @tags: [requires_non_retryable_writes]

// Check that the positional operator works properly when an index only match is used for the update
// query spec.  SERVER-5067

const t = db[jsTestName()];
t.drop();

function testPositionalInc() {
    assert.commandWorked(t.remove({}));
    assert.commandWorked(t.save({a: [{b: 'match', count: 0}]}));
    assert.commandWorked(t.update({'a.b': 'match'}, {$inc: {'a.$.count': 1}}));
    // Check that the positional $inc succeeded.
    assert(t.findOne({'a.count': 1}));
}

testPositionalInc();

// Now check with a non multikey index.
assert.commandWorked(t.createIndex({'a.b': 1}));
testPositionalInc();