createMock(HttpClient::class); $clientMock->expects($this->once()) ->method('request') ->willReturn($this->createMock(PingResponse::class)); $requestMock = $this->createMock(PingRequest::class); $api = new HeartbeatApiClient($clientMock); $_ = $api->sendPing($requestMock); $this->assertInstanceOf(PingResponse::class, $_); } }