Align Filter Chain Observability Lineage

Closes gh-12849

web/src/test/java/org/springframework/security/web/server/ObservationWebFilterChainDecoratorTests.java

@@ -16,15 +16,22 @@
 
 package org.springframework.security.web.server;
 
+import java.util.ArrayList;
+import java.util.List;
+
+import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationHandler;
 import io.micrometer.observation.ObservationRegistry;
+import io.micrometer.observation.contextpropagation.ObservationThreadLocalAccessor;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Mono;
 
 import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
 import org.springframework.mock.web.server.MockServerWebExchange;
+import org.springframework.web.server.WebFilter;
 import org.springframework.web.server.WebFilterChain;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
@@ -64,4 +71,147 @@ public class ObservationWebFilterChainDecoratorTests {
 		verifyNoInteractions(handler);
 	}
 
+	// gh-12849
+	@Test
+	void decorateWhenCustomAfterFilterThenObserves() {
+		AccumulatingObservationHandler handler = new AccumulatingObservationHandler();
+		ObservationRegistry registry = ObservationRegistry.create();
+		registry.observationConfig().observationHandler(handler);
+		ObservationWebFilterChainDecorator decorator = new ObservationWebFilterChainDecorator(registry);
+		WebFilter mock = mock(WebFilter.class);
+		given(mock.filter(any(), any())).willReturn(Mono.empty());
+		WebFilterChain chain = mock(WebFilterChain.class);
+		given(chain.filter(any())).willReturn(Mono.empty());
+		WebFilterChain decorated = decorator.decorate(chain,
+				List.of((e, c) -> c.filter(e).then(Mono.deferContextual((context) -> {
+					Observation parentObservation = context.getOrDefault(ObservationThreadLocalAccessor.KEY, null);
+					Observation observation = Observation.createNotStarted("custom", registry)
+							.parentObservation(parentObservation).contextualName("custom").start();
+					return Mono.just("3").doOnSuccess((v) -> observation.stop()).doOnCancel(observation::stop)
+							.doOnError((t) -> {
+								observation.error(t);
+								observation.stop();
+							}).then(Mono.empty());
+				}))));
+		Observation http = Observation.start("http", registry).contextualName("http");
+		try {
+			decorated.filter(MockServerWebExchange.from(MockServerHttpRequest.get("/").build()))
+					.contextWrite((context) -> context.put(ObservationThreadLocalAccessor.KEY, http)).block();
+		}
+		finally {
+			http.stop();
+		}
+		handler.assertSpanStart(0, "http", null);
+		handler.assertSpanStart(1, "spring.security.filterchains", "http");
+		handler.assertSpanStop(2, "security filterchain before");
+		handler.assertSpanStart(3, "secured request", "security filterchain before");
+		handler.assertSpanStop(4, "secured request");
+		handler.assertSpanStart(5, "spring.security.filterchains", "http");
+		handler.assertSpanStart(6, "custom", "spring.security.filterchains");
+		handler.assertSpanStop(7, "custom");
+		handler.assertSpanStop(8, "security filterchain after");
+		handler.assertSpanStop(9, "http");
+	}
+
+	static class AccumulatingObservationHandler implements ObservationHandler<Observation.Context> {
+
+		List<Event> contexts = new ArrayList<>();
+
+		@Override
+		public boolean supportsContext(Observation.Context context) {
+			return true;
+		}
+
+		@Override
+		public void onStart(Observation.Context context) {
+			this.contexts.add(new Event("start", context));
+		}
+
+		@Override
+		public void onError(Observation.Context context) {
+			this.contexts.add(new Event("error", context));
+		}
+
+		@Override
+		public void onEvent(Observation.Event event, Observation.Context context) {
+			this.contexts.add(new Event("event", context));
+		}
+
+		@Override
+		public void onScopeOpened(Observation.Context context) {
+			this.contexts.add(new Event("opened", context));
+		}
+
+		@Override
+		public void onScopeClosed(Observation.Context context) {
+			this.contexts.add(new Event("closed", context));
+		}
+
+		@Override
+		public void onScopeReset(Observation.Context context) {
+			this.contexts.add(new Event("reset", context));
+		}
+
+		@Override
+		public void onStop(Observation.Context context) {
+			this.contexts.add(new Event("stop", context));
+		}
+
+		private void assertSpanStart(int index, String name, String parentName) {
+			Event event = this.contexts.get(index);
+			assertThat(event.event).isEqualTo("start");
+			if (event.contextualName == null) {
+				assertThat(event.name).isEqualTo(name);
+			}
+			else {
+				assertThat(event.contextualName).isEqualTo(name);
+			}
+			if (parentName == null) {
+				return;
+			}
+			if (event.parentContextualName == null) {
+				assertThat(event.parentName).isEqualTo(parentName);
+			}
+			else {
+				assertThat(event.parentContextualName).isEqualTo(parentName);
+			}
+		}
+
+		private void assertSpanStop(int index, String name) {
+			Event event = this.contexts.get(index);
+			assertThat(event.event).isEqualTo("stop");
+			if (event.contextualName == null) {
+				assertThat(event.name).isEqualTo(name);
+			}
+			else {
+				assertThat(event.contextualName).isEqualTo(name);
+			}
+		}
+
+		static class Event {
+
+			String event;
+
+			String name;
+
+			String contextualName;
+
+			String parentName;
+
+			String parentContextualName;
+
+			Event(String event, Observation.Context context) {
+				this.event = event;
+				this.name = context.getName();
+				this.contextualName = context.getContextualName();
+				if (context.getParentObservation() != null) {
+					this.parentName = context.getParentObservation().getContextView().getName();
+					this.parentContextualName = context.getParentObservation().getContextView().getContextualName();
+				}
+			}
+
+		}
+
+	}
+
 }