Change default BootstrapMode for JPA repositories

Change the default `BootstrapMode` for auto-configured `JpaRepositories`
to `BootstrapMode.DEFERRED` to allow the initialization of
`EntityManagerFactory` to be parallelized for increased startup efficiency.

Prior to this change, the default BootstrapMode for all auto-configured
Spring Data repositories was `BootstrapMode.DEFAULT`.

Closes gh-16230

spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/orm/jpa/DataJpaTestAttributesIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -20,17 +20,18 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.core.env.Environment;
+import org.springframework.data.repository.config.BootstrapMode;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * Tests for the {@link DataJpaTest#properties properties} attribute of
- * {@link DataJpaTest @DataJpaTest}.
+ * Tests for non-default attributes of {@link DataJpaTest @DataJpaTest}.
  *
  * @author Artsiom Yudovin
+ * @author Scott Frederick
  */
-@DataJpaTest(properties = "spring.profiles.active=test")
-class DataJpaTestPropertiesIntegrationTests {
+@DataJpaTest(properties = "spring.profiles.active=test", bootstrapMode = BootstrapMode.DEFERRED)
+class DataJpaTestAttributesIntegrationTests {
 
 	@Autowired
 	private Environment environment;
@@ -40,4 +41,10 @@ class DataJpaTestPropertiesIntegrationTests {
 		assertThat(this.environment.getActiveProfiles()).containsExactly("test");
 	}
 
+	@Test
+	void bootstrapModeIsSet() {
+		assertThat(this.environment.getProperty("spring.data.jpa.repositories.bootstrap-mode"))
+				.isEqualTo(BootstrapMode.DEFERRED.name());
+	}
+
 }

spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/orm/jpa/DataJpaTestIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -25,6 +25,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration;
 import org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration;
 import org.springframework.context.ApplicationContext;
+import org.springframework.data.repository.config.BootstrapMode;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.test.context.TestPropertySource;
 
@@ -37,6 +38,7 @@ import static org.springframework.boot.test.autoconfigure.AutoConfigurationImpor
  *
  * @author Phillip Webb
  * @author Andy Wilkinson
+ * @author Scott Frederick
  */
 @DataJpaTest
 @TestPropertySource(properties = "spring.jpa.hibernate.use-new-id-generator-mappings=false")
@@ -106,4 +108,10 @@ class DataJpaTestIntegrationTests {
 		assertThat(this.applicationContext).has(importedAutoConfiguration(LiquibaseAutoConfiguration.class));
 	}
 
+	@Test
+	void bootstrapModeIsLazyByDefault() {
+		assertThat(this.applicationContext.getEnvironment().getProperty("spring.data.jpa.repositories.bootstrap-mode"))
+				.isEqualTo(BootstrapMode.LAZY.name());
+	}
+
 }