Unit testing Armeria's decorator using context.log().whenComplete() - armeria

Question

I have a subclass of SimpleDecoratingHttpService that contains something like this:
override fun serve(ctx: ServiceRequestContext, req: HttpRequest): HttpResponse {
ctx.log().whenComplete().thenAccept {
if (it.responseCause() == ...) {
// do stuff
}
}
return unwrap().serve(ctx, req)
}
I want to test the logic inside the whenComplete() callback. However, when writing tests like this:
myDecorator.serve(context, request).aggregate().join()
the log() future never completes. What do I need to do to ensure that the log() future eventually completes?

Answer 1

Emulating RequestLog completion
A RequestLog is completed by Armeria's networking layer, so just consuming an HttpRequest or HttpResponse will not complete a RequestLog. To complete it, you need to call the methods in RequestLogBuilder:
var myDecorator = new MySimpleDecoratingHttpService(...);
var ctx = ServiceRequestContext.of(
HttpRequest.of(HttpMethod.GET, "/hello"));
var req = ctx.request();
var res = myDecorator.serve(ctx, ctx.req).aggregate().join();
// Fill the log.
ctx.logBuilder().endRequest();
assert ctx.log().isRequestComplete();
ctx.logBuilder().responseHeaders(ResponseHeaders.of(200));
ctx.logBuilder().endResponse();
assert ctx.log().isComplete();
Armeria team uses the same technique for testing BraveService, so you might want to check it out as well at BraveServiceTest.java:161.
Testing with a real server
If your setup is too complex to use a mock, as an alternative approach, you can launch a real Armeria server so that Armeria fills the log for you. You can easily launch a server using ServerRule (JUnit 4) or ServerExtension (JUnit 5):
class MyJUnit5Test {
static final var serviceContexts =
new LinkedBlockingQueue<ServiceRequestContext>();
#RegisterExtension
static final var server = new ServerExtension() {
#Override
protected void configure(ServerBuilder sb) throws Exception {
sb.service("/hello", (ctx, req) -> HttpResponse.of(200));
sb.decorator(delegate -> new MySimpleDecoratingHttpService(delegate, ...));
// Record the ServiceRequestContext of each request.
sb.decorator((delegate, ctx, req) -> {
serviceContexts.add(ctx);
return delegate.serve(ctx, req);
});
}
};
#BeforeEach
void clearServiceContexts() {
serviceContexts.clear();
}
#Test
void test() {
// Send a real request.
var client = WebClient.of(server.httpUri());
var res = client.get("/hello").aggregate().join();
// Get the ServiceRequestContext and its log.
var ctx = serviceContexts.take();
var log = sctx.log().whenComplete().join();
// .. check `log` here ..
assertEquals(200, log.responseHeaders().status().code());
}
}