@Test
  void parsesErrorResponseBody() {
    String expectedResponseBody = "ARGHH";

    server.enqueue(new MockResponse().setResponseCode(500).setBody("ARGHH"));

    TestInterface api =
        newBuilder().target(TestInterface.class, "http://localhost:" + server.getPort());

    try {
      api.get();
    } catch (FeignException e) {
      assertThat(e.contentUTF8()).isEqualTo(expectedResponseBody);
    }
  }
Some client implementation tests should override this test if the PATCH operation is
unsupported.
core/src/test/java/feign/client/AbstractClientTest.java