WebTestClient is missing the ability to perform assertions against XML content like you can do with MockMvc (like with MockMvcResultMatchers.xpath). This is essential for building enterprise applications which have to support both XML & JSON.
I propose we add similar things to org.springframework.test.web.reactive.server.WebTestClient.BodyContentSpec as well as a new XpathAssertions class (similar to JsonPathAssertions) that ties into org.springframework.test.util.XpathExpectationsHelper.
#21270 WebTestClient does not provide Hamcrest Matcher assertions for JSONPath
I just wanted to see what may be going on with this one. Currently WebTestClient doesn't allow any kind of assertions against XML-based content. For enterprise applications with legacy services that are XML-based, until we have this capability we can not build reactive applications as we really have no way of testing them. We have lots of legacy services which call newer services we are building and those newer services have to be able to support both XML & JSON.