public function testListDomesticLetterThicknesses() { $this->setMockResponse($this->client, array('postage/list_domestic_letter_thicknesses')); $response = $this->client->listDomesticLetterThicknesses(); $this->assertArrayHasKey('thicknesses', $response); $this->assertArrayHasKey('thickness', $response['thicknesses']); $this->assertCount(2, $response['thicknesses']['thickness']); }