@include test-module('_map-keys') {
    $list: (1, 2);
    $map: ('a': 1, 'b': 2, 'c': 3);

    @include test('should map keys in $map to a new map') {
        $expected: ('1': 1, '2': 2, '3': 3);

        @include assert-maps-equal(
            _map-keys($map, _to-string),
            $expected);
    }

    @include test('should treat lists like maps') {
        $expected: ('1': 1, '2': 2);

        @include assert-maps-equal(
            _map-keys($list, _to-string),
            $expected);
    }

    @include test('should work with a _property style iteratee') {
        $nested-map: ('a': ('b': 'c'));
        $expected: ('c': ('b': 'c'));

        @include assert-maps-equal(
            _map-keys($nested-map, 'b'),
            $expected);
    }

    @include test('should work on a map with no iteratee') {
        $expected: (1: 1, 2: 2, 3: 3);

        @include assert-maps-equal(
            _map-keys($map),
            $expected);
    }

    @include test('should only use keys as value of iteratee when $with-keys is true') {
        $expected: ('A': 1, 'B': 2, 'C': 3);

        @include assert-maps-equal(
            // Pending bug fix: https://github.com/sass/libsass/issues/1579
            // Works when all arguments are specified
            _map-keys($map, to-upper-case, null, $with-keys: true),
            $expected);
    }
}