@function test-assign-1($a, $b, $args...) {
    @return if($a == null or $a == $__undefined__, $b, $a);
}
@include test-module('_assign') {
    @include test('should assign properties of a source object to the destination object') {
        @include assert-equal(_assign(('a': 1), ('b': 2)), ('a': 1, 'b': 2));
    }

    @include test('should accept multiple source objects') {
        $expected: ('a': 1, 'b': 2, 'c': 3);

        @include assert-equal(_assign(('a': 1), ('b': 2), ('c': 3)), $expected);
        @include assert-equal(_assign(('a': 1), ('b': 2, 'c': 2), ('c': 3)), $expected);
    }

    @include test('should overwrite destination properties') {
        $expected: ('a': 3, 'b': 2, 'c': 1);

        @include assert-equal(_assign(('a': 1, 'b': 2), $expected), $expected);
    }

    @include test('should work with a customizer callback') {
        $actual: _assign(('a': 1, 'b': 2), ('a': 3, 'c': 3), test-assign-1);
        $expected: ('a': 1, 'b': 2, 'c': 3);

        @include assert-equal($actual, $expected);
    }
}

@include test-module('map assignments') {  
  // TODO: add 'merge'
  @each $method-name in 'assign', 'defaults' {
    $func: unquote('_#{$method-name}');

    @each $value in $test-falsey {
      $actual: _call($func, null, $value);
      $expected: $value;

      @include test('#{$func} should pass thru falsey map values') {
        @include assert-equal($actual, $expected);
      }
    }

    $list: (('b': 2), ('c': 3));
    $actual: _reduce($list, $func, ('a': 1));
    $expected: ('a': 1, 'b': 2, 'c': 3);

    @include test('#{$func} should work as an iteratee for _reduce') {
      @include assert-equal($actual, $expected);
    }
  }
}