Add Blockhound to test setup.

pom.xml

@@ -24,6 +24,7 @@
 		<netty>4.1.52.Final</netty>
 		<springdata.commons>2.6.0-SNAPSHOT</springdata.commons>
 		<testcontainers>1.15.1</testcontainers>
+		<blockhound-junit>1.0.6.RELEASE</blockhound-junit>
 		<java-module-name>spring.data.elasticsearch</java-module-name>
 	</properties>
 
@@ -256,6 +257,14 @@
 			<scope>test</scope>
 		</dependency>
 
+		<dependency>
+			<groupId>io.projectreactor.tools</groupId>
+			<artifactId>blockhound-junit-platform</artifactId>
+			<version>${blockhound-junit}</version>
+			<scope>test</scope>
+		</dependency>
+
+
 		<!--
 		  we don't use lombok in Spring Data Elasticsearch anymore. But the dependency is set in the parent project, and so the
 		  lombok compiler stuff is executed regardless of the fact that we don't need it.
@@ -272,24 +281,24 @@
 			<scope>test</scope>
 		</dependency>
 
-<!--
-		<dependency>
-			<groupId>org.apache.openwebbeans.test</groupId>
-			<artifactId>cditest-owb</artifactId>
-			<version>1.2.8</version>
-			<scope>test</scope>
-			<exclusions>
-				<exclusion>
-					<groupId>org.apache.geronimo.specs</groupId>
-					<artifactId>geronimo-jcdi_1.0_spec</artifactId>
-				</exclusion>
-				<exclusion>
-					<groupId>org.apache.geronimo.specs</groupId>
-					<artifactId>geronimo-atinject_1.0_spec</artifactId>
-				</exclusion>
-			</exclusions>
-		</dependency>
--->
+		<!--
+				<dependency>
+					<groupId>org.apache.openwebbeans.test</groupId>
+					<artifactId>cditest-owb</artifactId>
+					<version>1.2.8</version>
+					<scope>test</scope>
+					<exclusions>
+						<exclusion>
+							<groupId>org.apache.geronimo.specs</groupId>
+							<artifactId>geronimo-jcdi_1.0_spec</artifactId>
+						</exclusion>
+						<exclusion>
+							<groupId>org.apache.geronimo.specs</groupId>
+							<artifactId>geronimo-atinject_1.0_spec</artifactId>
+						</exclusion>
+					</exclusions>
+				</dependency>
+		-->
 
 		<dependency>
 			<groupId>org.skyscreamer</groupId>
@@ -448,9 +457,7 @@
 
 	<profiles>
 		<profile>
-
 			<id>ci</id>
-
 			<build>
 				<plugins>
 					<plugin>
@@ -473,9 +480,26 @@
 					</plugin>
 				</plugins>
 			</build>
-
 		</profile>
 
+		<profile>
+			<id>jdk13+</id>
+			<!-- on jDK13+, Blockhound needs this JVM flag set -->
+			<activation>
+				<jdk>[13,)</jdk>
+			</activation>
+			<build>
+				<plugins>
+					<plugin>
+						<groupId>org.apache.maven.plugins</groupId>
+						<artifactId>maven-surefire-plugin</artifactId>
+						<configuration>
+							<argLine>-XX:+AllowRedefinitionToAddDeleteMethods</argLine>
+						</configuration>
+					</plugin>
+				</plugins>
+			</build>
+		</profile>
 	</profiles>
 
 	<repositories>

src/test/java/org/springframework/data/elasticsearch/blockhound/BlockHoundIntegrationCustomizer.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2021 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.data.elasticsearch.blockhound;
+
+import reactor.blockhound.BlockHound;
+import reactor.blockhound.integration.BlockHoundIntegration;
+
+import org.elasticsearch.Build;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.springframework.data.elasticsearch.support.VersionInfo;
+
+/**
+ * @author Peter-Josef Meisch
+ */
+public class BlockHoundIntegrationCustomizer implements BlockHoundIntegration {
+	@Override
+	public void applyTo(BlockHound.Builder builder) {
+		// Elasticsearch classes reading from the classpath on initialization, needed for parsing Elasticsearch responses
+		builder.allowBlockingCallsInside(XContentBuilder.class.getName(), "<clinit>")
+				.allowBlockingCallsInside(Build.class.getName(), "<clinit>");
+
+		// Spring Data Elasticsearch classes reading from the classpath
+		builder.allowBlockingCallsInside(VersionInfo.class.getName(), "logVersions");
+	}
+}

src/test/java/org/springframework/data/elasticsearch/blockhound/BlockHoundTests.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2021 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.data.elasticsearch.blockhound;
+
+import static org.assertj.core.api.Assertions.*;
+
+import reactor.blockhound.BlockingOperationError;
+import reactor.core.publisher.Mono;
+
+import java.time.Duration;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author Peter-Josef Meisch
+ */
+public class BlockHoundTests {
+
+	@Test // #1822
+	@DisplayName("should fail if BlockHound is not installed")
+	void shouldFailIfBlockHoundIsNotInstalled() {
+
+		assertThatThrownBy(() -> {
+			Mono.delay(Duration.ofMillis(1)).doOnNext(it -> {
+				try {
+					Thread.sleep(10);
+				} catch (InterruptedException e) {
+					throw new RuntimeException(e);
+				}
+			}).block(); // should throw an exception about Thread.sleep
+		}).hasCauseInstanceOf(BlockingOperationError.class);
+	}
+}

src/test/java/org/springframework/data/elasticsearch/core/index/ReactiveMappingBuilderIntegrationTests.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2021 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.data.elasticsearch.core.index;
+
+import static org.springframework.data.elasticsearch.annotations.FieldType.*;
+
+import java.time.Instant;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.annotation.Id;
+import org.springframework.data.elasticsearch.annotations.DateFormat;
+import org.springframework.data.elasticsearch.annotations.Document;
+import org.springframework.data.elasticsearch.annotations.Field;
+import org.springframework.data.elasticsearch.annotations.Mapping;
+import org.springframework.data.elasticsearch.core.ReactiveElasticsearchOperations;
+import org.springframework.data.elasticsearch.core.ReactiveIndexOperations;
+import org.springframework.data.elasticsearch.junit.jupiter.ReactiveElasticsearchRestTemplateConfiguration;
+import org.springframework.data.elasticsearch.junit.jupiter.SpringIntegrationTest;
+import org.springframework.lang.Nullable;
+import org.springframework.test.context.ContextConfiguration;
+
+/**
+ * @author Peter-Josef Meisch
+ */
+@SpringIntegrationTest
+@ContextConfiguration(classes = { ReactiveElasticsearchRestTemplateConfiguration.class })
+public class ReactiveMappingBuilderIntegrationTests {
+
+	@Autowired private ReactiveElasticsearchOperations operations;
+
+	@Test // #1822
+	@DisplayName("should write runtime fields")
+	void shouldWriteRuntimeFields() {
+
+		ReactiveIndexOperations indexOps = operations.indexOps(RuntimeFieldEntity.class);
+
+		indexOps.create().block();
+		indexOps.putMapping().block();
+		indexOps.delete().block();
+	}
+
+	// region entities
+	@Document(indexName = "runtime-fields")
+	@Mapping(runtimeFieldsPath = "/mappings/runtime-fields.json")
+	private static class RuntimeFieldEntity {
+		@Id @Nullable private String id;
+		@Field(type = Date, format = DateFormat.epoch_millis, name = "@timestamp") @Nullable private Instant timestamp;
+	}
+	// endregion
+}

src/test/resources/META-INF/services/reactor.blockhound.integration.BlockHoundIntegration

@@ -0,0 +1 @@
+org.springframework.data.elasticsearch.blockhound.BlockHoundIntegrationCustomizer