@Test
public void constructor_with_HttpMessage_arg_sets_fields_as_expected() {
    // given
    HttpHeaders headersMock = mock(HttpHeaders.class);
    HttpMessage messageMock = mock(HttpMessage.class);
    doReturn(headersMock).when(messageMock).getHeaders();

    // when
    HttpHeadersForPropagation impl = new HttpHeadersForPropagation(messageMock);

    // then
    assertThat(impl.httpHeaders).isSameAs(headersMock);
}
 

@Test
public void constructor_with_HttpMessage_arg_throws_IllegalArgumentException_when_passed_null() {
    // when
    Throwable ex = catchThrowable(() -> new HttpHeadersForPropagation((HttpMessage)null));

    // then
    assertThat(ex)
        .isInstanceOf(IllegalArgumentException.class)
        .hasMessage("httpMessage cannot be null");
}
 

@Before
public void beforeMethod() {
    resetTracing();

    httpMessageMock = mock(HttpMessage.class);
    headersMock = mock(HttpHeaders.class);
    doReturn(headersMock).when(httpMessageMock).getHeaders();

    successCallbackMock = mock(SuccessCallback.class);
    failureCallbackMock = mock(FailureCallback.class);
    listenableFutureCallbackMock = mock(ListenableFutureCallback.class);

    tagStrategyMock = mock(HttpTagAndSpanNamingStrategy.class);
    tagAdapterMock = mock(HttpTagAndSpanNamingAdapter.class);
}
 

private void log(HttpMessage message) throws IOException {
  if(message instanceof HttpRequest) {
    HttpRequest request = (HttpRequest) message;
    log.info("URI: {}", request.getURI());
    log.info("Method: {}", request.getMethod());
  } else if(message instanceof ClientHttpResponse) {
    ClientHttpResponse response = (ClientHttpResponse) message;
    log.info("Status code: {}", response.getStatusCode());
  } else {
    return;
  }
  log.info("Headers:");
  message.getHeaders().forEach((k, v) -> log.info("    " + k + ": " + v));
  log.info("----------------------------------------------------------------------------");
}
 

protected void setContentLength(final HttpMessage message, final byte[] messageBody) {
  message.getHeaders().setContentLength(messageBody.length);
}
 

public HttpHeadersForPropagation(HttpMessage httpMessage) {
    this(extractHttpHeaders(httpMessage));
}
 

protected static HttpHeaders extractHttpHeaders(HttpMessage httpMessage) {
    if (httpMessage == null) {
        throw new IllegalArgumentException("httpMessage cannot be null");
    }
    return httpMessage.getHeaders();
}
 

protected void setContentLength(final HttpMessage message, final byte[] messageBody) {
  message.getHeaders().setContentLength(messageBody.length);
}
 

/**
 * Sets the tracing headers on the given {@link HttpMessage#getHeaders()} with values from the given {@link Span}.
 * Does nothing if any of the given arguments are null (i.e. it is safe to pass null, but nothing will happen).
 * Usually you'd want to use one of the interceptors to handle tracing propagation for you
 * ({@link WingtipsClientHttpRequestInterceptor} or {@link WingtipsAsyncClientHttpRequestInterceptor}), however
 * you can call this method to do manual propagation if needed.
 *
 * <p>This method conforms to the <a href="https://github.com/openzipkin/b3-propagation">B3 propagation spec</a>.
 *
 * @param httpMessage The {@link HttpMessage} to set tracing headers on. Can be null - if this is null then this
 * method will do nothing.
 * @param span The {@link Span} to get the tracing info from to set on the headers. Can be null - if this is null
 * then this method will do nothing.
 */
public static void propagateTracingHeaders(HttpMessage httpMessage, Span span) {
    HttpHeadersForPropagation headersForPropagation = (httpMessage == null)
                                                      ? null
                                                      : new HttpHeadersForPropagation(httpMessage);
    HttpRequestTracingUtils.propagateTracingHeaders(headersForPropagation, span);
}
 

/**
 * Determine the Content-Type of the HTTP message based on the
 * "Content-Type" header or otherwise default to
 * {@link MediaType#APPLICATION_OCTET_STREAM}.
 * @param inputMessage the HTTP message
 * @return the MediaType, possibly {@code null}.
 */
@Nullable
protected MediaType getContentType(HttpMessage inputMessage) {
	MediaType contentType = inputMessage.getHeaders().getContentType();
	return (contentType != null ? contentType : MediaType.APPLICATION_OCTET_STREAM);
}
 

/**
 * Determine the Content-Type of the HTTP message based on the
 * "Content-Type" header or otherwise default to
 * {@link MediaType#APPLICATION_OCTET_STREAM}.
 * @param inputMessage the HTTP message
 * @return the MediaType, possibly {@code null}.
 */
@Nullable
protected MediaType getContentType(HttpMessage inputMessage) {
	MediaType contentType = inputMessage.getHeaders().getContentType();
	return (contentType != null ? contentType : MediaType.APPLICATION_OCTET_STREAM);
}