Crash with POST requests and WebTestClient: Request body incomplete.

Hi.

I’m getting the following crash

java.lang.IllegalArgumentException: Request body incomplete.

	at org.springframework.util.Assert.isTrue(Assert.java:116)
	at org.springframework.test.web.reactive.server.ExchangeResult.getRequestBodyContent(ExchangeResult.java:149)
	at org.springframework.restdocs.webtestclient.WebTestClientRequestConverter.convert(WebTestClientRequestConverter.java:73)
	at org.springframework.restdocs.webtestclient.WebTestClientRequestConverter.convert(WebTestClientRequestConverter.java:60)
	at org.springframework.restdocs.generate.RestDocumentationGenerator.handle(RestDocumentationGenerator.java:199)
	at org.springframework.restdocs.webtestclient.WebTestClientRestDocumentation.lambda$document$0(WebTestClientRestDocumentation.java:81)
	at org.springframework.test.web.reactive.server.DefaultWebTestClient$DefaultBodyContentSpec.lambda$consumeWith$2(DefaultWebTestClient.java:496)
	at org.springframework.test.web.reactive.server.ExchangeResult.assertWithDiagnostics(ExchangeResult.java:194)
	at org.springframework.test.web.reactive.server.DefaultWebTestClient$DefaultBodyContentSpec.consumeWith(DefaultWebTestClient.java:496)
	at MyTest.testMain(MyTest.java:72)

The issue is related with the use of a request body with a post request. This happens due to an assert Assert.isTrue(MonoProcessor.isTerminated(). Inspecting that method isTerminated returns subscribers == TERMINATED, but in the case of the request body, debugging shows that subscribers == EMPTY.

Testcase follows.

[joaoe]

I finally pinpointed the problem: the class WiretapConnector.WiretapClientHttpRequest caches the request body, which is then relayed to the rest docs code. If the request body is not injected into the @RequestMapping, then the original publisher is never written and the MonoProcessor never reaches the terminated state.

This fixes the test case

@PostMapping(path=END_POINT, produces=MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<String> handlePutPoll(@RequestBody String stuff) {
  // ...
}

[joaoe]

Ok. Thanks for the input. Cheers.

PS: One of the very last classes in the stack is org.springframework.restdocs.webtestclient.WebTestClientRequestConverter so I asked about the error message.