@Test
public void shouldShowJson() throws IOException {

    HttpURLConnection connection = (HttpURLConnection) new URL(server.getURL() + "/demo/openapi.yaml").openConnection();
    assertThat(connection.getResponseCode()).isEqualTo(200);
    StringWriter writer = new StringWriter();
    new BufferedReader(new InputStreamReader(connection.getInputStream())).transferTo(writer);
    assertThat(writer.toString())
            .contains("Swagger Petstore");
}