public function test_output_add_onclick()
 {
     // Case 1
     $link_attribute = '<a href="/test.html" onclick="alert(\'Test\');">link content</a>';
     $onclick_add = 'dofunction();';
     $this->assertEquals($this->class_instance->output_add_onclick($link_attribute, $onclick_add), '<a href="/test.html" onclick="alert(\'Test\'); dofunction();">link content</a>');
     // Case 2
     $link_attribute = '<a href="/test.html" onclick="alert(\'Test\');" data-title="test title">link content</a>';
     $onclick_add = 'dofunction();';
     $this->assertEquals($this->class_instance->output_add_onclick($link_attribute, $onclick_add), '<a href="/test.html" onclick="alert(\'Test\'); dofunction();" data-title="test title">link content</a>');
 }