$this->drupalGet("forum/$tid");
$this->clickLink(t('Add new @node_type', ['@node_type' => 'Forum topic']));
$this->assertUrl('node/add/forum', ['query' => ['forum_id' => $tid]]);
$this->drupalGet("forum/$tid");
$this->clickLink(t('Add new @node_type', ['@node_type' => 'Forum topic']));
$this->assertUrl('node/add/forum', ['query' => ['forum_id' => $tid]]);