public function testRegex()
 {
     $regex = 'wom(a|e)n';
     $expectedQuery = ['regexp' => ['gender' => $regex]];
     $this->queryBuilder->regex('gender', $regex);
     $this->assertExpectedQuery($expectedQuery);
     $boost = rand(1, 5);
     $expectedQuery = ['regexp' => ['gender' => ['value' => $regex, 'boost' => $boost]]];
     $this->queryBuilder->regex('gender', ['value' => $regex, 'boost' => $boost]);
     $this->assertExpectedQuery($expectedQuery);
 }