Merge branch '6.0.x'

spring-core/src/test/java/org/springframework/core/ReactiveAdapterRegistryTests.java

@@ -39,6 +39,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Unit tests for {@link ReactiveAdapterRegistry}.
  *
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  */
 @SuppressWarnings("unchecked")
 class ReactiveAdapterRegistryTests {
@@ -54,14 +55,40 @@ class ReactiveAdapterRegistryTests {
 		ReactiveAdapter adapter2 = getAdapter(ExtendedFlux.class);
 		assertThat(adapter2).isSameAs(adapter1);
 
+		// Register regular reactive type (after existing adapters)
 		this.registry.registerReactiveType(
 				ReactiveTypeDescriptor.multiValue(ExtendedFlux.class, ExtendedFlux::empty),
 				o -> (ExtendedFlux<?>) o,
 				ExtendedFlux::from);
 
+		// Matches for ExtendedFlux itself
 		ReactiveAdapter adapter3 = getAdapter(ExtendedFlux.class);
 		assertThat(adapter3).isNotNull();
 		assertThat(adapter3).isNotSameAs(adapter1);
+
+		// Does not match for ExtendedFlux subclass since the default Flux adapter
+		// is being assignability-checked first when no specific match was found
+		ReactiveAdapter adapter4 = getAdapter(ExtendedExtendedFlux.class);
+		assertThat(adapter4).isSameAs(adapter1);
+
+		// Register reactive type override (before existing adapters)
+		this.registry.registerReactiveTypeOverride(
+				ReactiveTypeDescriptor.multiValue(Flux.class, ExtendedFlux::empty),
+				o -> (ExtendedFlux<?>) o,
+				ExtendedFlux::from);
+
+		// Override match for Flux
+		ReactiveAdapter adapter5 = getAdapter(Flux.class);
+		assertThat(adapter5).isNotNull();
+		assertThat(adapter5).isNotSameAs(adapter1);
+
+		// Initially registered adapter specifically matches for ExtendedFlux
+		ReactiveAdapter adapter6 = getAdapter(ExtendedFlux.class);
+		assertThat(adapter6).isSameAs(adapter3);
+
+		// Override match for ExtendedFlux subclass
+		ReactiveAdapter adapter7 = getAdapter(ExtendedExtendedFlux.class);
+		assertThat(adapter7).isSameAs(adapter5);
 	}
 
 
@@ -81,6 +108,10 @@ class ReactiveAdapterRegistryTests {
 	}
 
 
+	private static class ExtendedExtendedFlux<T> extends ExtendedFlux<T> {
+	}
+
+
 	@Nested
 	class Reactor {