private void ensureSignedUrlCreationFailure(AmbryUrlSigningService signer, RestRequest request,
      RestServiceErrorCode errorCode) {
    try {
      signer.getSignedUrl(request);
      fail("Should have failed to create a signed URL");
    } catch (RestServiceException e) {
      assertEquals("Unexpected RestServiceErrorCode", errorCode, e.getErrorCode());
    }
  }
Ensures that construction of a signed URL from {@code request} fails.
@param signer the {@link AmbryUrlSigningService} to use.
@param request the {@link RestRequest} containing all the parameters for signing.
@param errorCode the {@link RestServiceErrorCode} expected when an attempt is made to the construct a signed URL.
ambry-frontend/src/test/java/com/github/ambry/frontend/AmbryUrlSigningServiceTest.java