Reactive support in MethodValidationInterceptor

Closes gh-20781

spring-context/src/test/java/org/springframework/validation/beanvalidation/MethodValidationProxyReactorTests.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2002-2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.validation.beanvalidation;
+
+import java.util.Set;
+
+import jakarta.validation.ConstraintViolation;
+import jakarta.validation.ConstraintViolationException;
+import jakarta.validation.Valid;
+import jakarta.validation.Validation;
+import jakarta.validation.Validator;
+import jakarta.validation.constraints.Size;
+import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
+
+import org.springframework.aop.framework.ProxyFactory;
+import org.springframework.validation.method.MethodValidationException;
+import org.springframework.validation.method.ParameterErrors;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ *
+ */
+public class MethodValidationProxyReactorTests {
+
+	@Test
+	void validMonoArgument() {
+		MyService myService = initProxy(new MyService(), false);
+		Mono<Person> personMono = Mono.just(new Person("Faustino1234"));
+
+		StepVerifier.create(myService.addPerson(personMono))
+				.expectErrorSatisfies(t -> {
+					ConstraintViolationException ex = (ConstraintViolationException) t;
+					Set<ConstraintViolation<?>> violations = ex.getConstraintViolations();
+					assertThat(violations).hasSize(1);
+					assertThat(violations.iterator().next().getMessage()).isEqualTo("size must be between 1 and 10");
+				})
+				.verify();
+	}
+
+	@Test
+	void validFluxArgument() {
+		MyService myService = initProxy(new MyService(), false);
+		Flux<Person> personFlux = Flux.just(new Person("Faust"), new Person("Faustino1234"));
+
+		StepVerifier.create(myService.addPersons(personFlux))
+				.expectErrorSatisfies(t -> {
+					ConstraintViolationException ex = (ConstraintViolationException) t;
+					Set<ConstraintViolation<?>> violations = ex.getConstraintViolations();
+					assertThat(violations).hasSize(1);
+					assertThat(violations.iterator().next().getMessage()).isEqualTo("size must be between 1 and 10");
+				})
+				.verify();
+	}
+
+	@Test
+	void validMonoArgumentWithAdaptedViolations() {
+		MyService myService = initProxy(new MyService(), true);
+		Mono<Person> personMono = Mono.just(new Person("Faustino1234"));
+
+		StepVerifier.create(myService.addPerson(personMono))
+				.expectErrorSatisfies(t -> {
+					MethodValidationException ex = (MethodValidationException) t;
+					assertThat(ex.getAllValidationResults()).hasSize(1);
+
+					ParameterErrors errors = ex.getBeanResults().get(0);
+					assertThat(errors.getErrorCount()).isEqualTo(1);
+					assertThat(errors.getFieldErrors().get(0).toString()).isEqualTo("""
+							Field error in object 'Person' on field 'name': rejected value [Faustino1234]; \
+							codes [Size.Person.name,Size.name,Size.java.lang.String,Size]; \
+							arguments [org.springframework.context.support.DefaultMessageSourceResolvable: \
+							codes [Person.name,name]; arguments []; default message [name],10,1]; \
+							default message [size must be between 1 and 10]""");
+				})
+				.verify();
+	}
+
+	private static MyService initProxy(Object target, boolean adaptViolations) {
+		Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
+		MethodValidationInterceptor interceptor = new MethodValidationInterceptor(() -> validator, adaptViolations);
+		ProxyFactory factory = new ProxyFactory(target);
+		factory.addAdvice(interceptor);
+		return (MyService) factory.getProxy();
+	}
+
+
+	@SuppressWarnings("unused")
+	static class MyService {
+
+		public Mono<Void> addPerson(@Valid Mono<Person> personMono) {
+			return personMono.then();
+		}
+
+		public Mono<Void> addPersons(@Valid Flux<Person> personFlux) {
+			return personFlux.then();
+		}
+	}
+
+
+	@SuppressWarnings("unused")
+	record Person(@Size(min = 1, max = 10) String name) {
+	}
+
+}