Incorrect data type for the expected parameter

Problem/Motivation

Incorrect data type for the $expected parameter.

 * @dataProvider providerFilterAttributes
 *
 * @param string $html
 *   Input HTML.
 * @param array $expected
 *   The expected output string.
 */
public function testfilterAttributes($html, $expected) {
  $this->assertSame($expected, $this->filter->filterAttributes($html));
}

/**
 * Provides data for testfilterAttributes.
 *
 * @return array
 *   An array of test data.
 */
public function providerFilterAttributes() {
  return [
    ['<a href="/blog" title="Blog">Blog</a>', '<a href="/blog">Blog</a>'],
    ['<p dir="rtl" />', '<p dir="rtl"></p>'],
    ['<p dir="bogus" />', '<p></p>'],

Proposed resolution

Should be a string.