Fix deprecation warnings

* Remove `forkEvery = 1000` since where the build fails there is no way find the reason
* Rework affected test classes to use JUnit 5 API
* Use Java text block for JSON snippets in the test

build.gradle

@@ -345,8 +345,6 @@ configure(javaProjects) { subproject ->
         reports.junitXml.required = false
 
         enableAssertions = false
-
-        forkEvery = 1000
     }
 
     checkstyle {

spring-integration-core/src/test/java/org/springframework/integration/aggregator/FluxAggregatorMessageHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2022 the original author or authors.
+ * Copyright 2019-2024 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.
@@ -23,6 +23,7 @@ import java.util.concurrent.Executors;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
+import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.DisabledIfEnvironmentVariable;
 import reactor.core.publisher.Flux;
@@ -132,8 +133,7 @@ class FluxAggregatorMessageHandlerTests {
 
 		Object payload = result.getPayload();
 		assertThat(payload)
-				.isInstanceOf(List.class)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.containsExactly(
 						IntStream.iterate(0, i -> i + 2)
 								.limit(10)
@@ -145,8 +145,7 @@ class FluxAggregatorMessageHandlerTests {
 
 		payload = result.getPayload();
 		assertThat(payload)
-				.isInstanceOf(List.class)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.containsExactly(
 						IntStream.iterate(1, i -> i + 2)
 								.limit(10)

spring-integration-core/src/test/java/org/springframework/integration/aggregator/integration/DefaultMessageAggregatorIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -17,8 +17,8 @@
 package org.springframework.integration.aggregator.integration;
 
 import java.util.Arrays;
-import java.util.List;
 
+import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -56,8 +56,8 @@ public class DefaultMessageAggregatorIntegrationTests {
 			this.input.send(prepareSequenceMessage(i, 5, 1));
 		}
 		Object payload = this.output.receive(20_000).getPayload();
-		assertThat(payload).isInstanceOf(List.class)
-				.asList()
+		assertThat(payload)
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.containsAll(Arrays.asList(0, 1, 2, 3, 4));
 	}
 

spring-integration-core/src/test/java/org/springframework/integration/channel/PartitionedChannelTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 the original author or authors.
+ * Copyright 2023-2024 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.
@@ -23,6 +23,7 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.stream.IntStream;
 
+import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.BeanFactory;
@@ -133,7 +134,7 @@ public class PartitionedChannelTests {
 
 		assertThat(receive).isNotNull()
 				.extracting(Message::getPayload)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.hasSize(5);
 
 		@SuppressWarnings("unchecked")

spring-integration-core/src/test/java/org/springframework/integration/dsl/correlation/CorrelationHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 the original author or authors.
+ * Copyright 2016-2024 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.
@@ -25,8 +25,8 @@ import java.util.stream.IntStream;
 
 import com.fasterxml.jackson.databind.node.ArrayNode;
 import com.fasterxml.jackson.databind.node.TextNode;
-import org.junit.Test;
-import org.junit.runner.RunWith;
+import org.assertj.core.api.InstanceOfAssertFactories;
+import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
 import reactor.test.StepVerifier;
 
@@ -53,16 +53,17 @@ import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.PollableChannel;
 import org.springframework.messaging.support.GenericMessage;
 import org.springframework.test.annotation.DirtiesContext;
-import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * @author Artem Bilan
  * @author Gary Russell
+ *
  * @since 5.0
  */
-@RunWith(SpringRunner.class)
+@SpringJUnitConfig
 @DirtiesContext
 public class CorrelationHandlerTests {
 
@@ -167,7 +168,7 @@ public class CorrelationHandlerTests {
 				.isInstanceOf(ArrayNode.class)
 				.extracting(new String[] {"_children"})
 				.element(0)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.hasSize(0);
 	}
 
@@ -207,7 +208,7 @@ public class CorrelationHandlerTests {
 	public static class ContextConfiguration {
 
 		@Bean
-		public TestSplitterPojo testSplitterData() {
+		TestSplitterPojo testSplitterData() {
 			List<String> first = new ArrayList<>();
 			first.add("1,2,3");
 			first.add("4,5,6");
@@ -324,26 +325,7 @@ public class CorrelationHandlerTests {
 
 	}
 
-	private static final class TestSplitterPojo {
-
-		final List<String> first;
-
-		final List<String> second;
-
-		TestSplitterPojo(List<String> first, List<String> second) {
-			this.first = first;
-			this.second = second;
-		}
-
-		@SuppressWarnings("unused")
-		public List<String> getFirst() {
-			return first;
-		}
-
-		@SuppressWarnings("unused")
-		public List<String> getSecond() {
-			return second;
-		}
+	record TestSplitterPojo(List<String> first, List<String> second) {
 
 		@SuppressWarnings("unused")
 		public List<List<String>> buildList() {

spring-integration-core/src/test/java/org/springframework/integration/json/JsonToObjectTransformerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -20,6 +20,7 @@ import java.util.List;
 
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.ParameterizedTypeReference;
@@ -49,13 +50,24 @@ public class JsonToObjectTransformerTests {
 		// Since DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES is disabled by default
 		// (see Jackson2JsonObjectMapper)
 		// the extra "foo" property is ignored.
-		String jsonString = "[{\"firstName\":\"John\",\"lastName\":\"Doe\",\"age\":42," +
-				"\"address\":{\"number\":123,\"street\":\"Main Street\"}, \"foo\":\"bar\"}]";
+		// language=JSON
+		String jsonString = """
+				[
+					{
+						"firstName": "John",
+						"lastName": "Doe",
+						"age": 42,
+						"address": {
+							"number": 123,
+							"street": "Main Street"
+						},
+						"foo": "bar"
+					}
+				]""";
 		Message<?> message = transformer.transform(new GenericMessage<>(jsonString));
 		assertThat(message)
 				.extracting(Message::getPayload)
-				.isInstanceOf(List.class)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.hasSize(1)
 				.element(0)
 				.isInstanceOf(TestPerson.class)
@@ -75,7 +87,17 @@ public class JsonToObjectTransformerTests {
 		customMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, Boolean.TRUE);
 		JsonToObjectTransformer transformer = new JsonToObjectTransformer(new Jackson2JsonObjectMapper(customMapper));
 		transformer.setValueTypeExpression(new ValueExpression<>(ResolvableType.forClass(TestPerson.class)));
-		String jsonString = "{firstName:'John', lastName:'Doe', age:42, address:{number:123, street:'Main Street'}}";
+		// language=JSON
+		String jsonString = """
+				{
+					"firstName": "John",
+					"lastName": "Doe",
+					"age": 42,
+					"address": {
+						"number": 123,
+						"street": "Main Street"
+					}
+				}""";
 		Message<?> message = transformer.transform(new GenericMessage<>(jsonString));
 		TestPerson person = (TestPerson) message.getPayload();
 		assertThat(person.getFirstName()).isEqualTo("John");

spring-integration-core/src/test/java/org/springframework/integration/scattergather/config/ScatterGatherTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2022 the original author or authors.
+ * Copyright 2014-2024 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.
@@ -16,10 +16,8 @@
 
 package org.springframework.integration.scattergather.config;
 
-import java.util.List;
-
-import org.junit.Test;
-import org.junit.runner.RunWith;
+import org.assertj.core.api.InstanceOfAssertFactories;
+import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.integration.gateway.RequestReplyExchanger;
@@ -28,8 +26,7 @@ import org.springframework.messaging.MessageChannel;
 import org.springframework.messaging.PollableChannel;
 import org.springframework.messaging.support.GenericMessage;
 import org.springframework.test.annotation.DirtiesContext;
-import org.springframework.test.context.ContextConfiguration;
-import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -39,8 +36,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @since 4.1
  */
-@ContextConfiguration
-@RunWith(SpringJUnit4ClassRunner.class)
+@SpringJUnitConfig
 @DirtiesContext
 public class ScatterGatherTests {
 
@@ -66,8 +62,7 @@ public class ScatterGatherTests {
 		assertThat(bestQuoteMessage)
 				.isNotNull()
 				.extracting(Message::getPayload)
-				.isInstanceOf(List.class)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.hasSizeGreaterThanOrEqualTo(1);
 	}
 
@@ -78,8 +73,7 @@ public class ScatterGatherTests {
 		assertThat(bestQuoteMessage)
 				.isNotNull()
 				.extracting(Message::getPayload)
-				.isInstanceOf(List.class)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.hasSizeGreaterThanOrEqualTo(1);
 	}
 
@@ -89,16 +83,14 @@ public class ScatterGatherTests {
 		assertThat(bestQuoteMessage)
 				.isNotNull()
 				.extracting(Message::getPayload)
-				.isInstanceOf(List.class)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.hasSizeGreaterThanOrEqualTo(1);
 
 		bestQuoteMessage = this.gateway.exchange(new GenericMessage<>("bar"));
 		assertThat(bestQuoteMessage)
 				.isNotNull()
 				.extracting(Message::getPayload)
-				.isInstanceOf(List.class)
-				.asList()
+				.asInstanceOf(InstanceOfAssertFactories.LIST)
 				.hasSizeGreaterThanOrEqualTo(1);
 	}