Polish "Upgrade to Flyway 4.0"

See gh-5344

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/flyway/FlywayAutoConfiguration.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -18,6 +18,7 @@ package org.springframework.boot.autoconfigure.flyway;
 
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Set;
 
 import javax.annotation.PostConstruct;
@@ -94,19 +95,20 @@ public class FlywayAutoConfiguration {
 
 		private final FlywayMigrationStrategy migrationStrategy;
 
-		private FlywayCallback[] flywayCallbacks;
+		private List<FlywayCallback> flywayCallbacks;
 
 		public FlywayConfiguration(FlywayProperties properties,
 				ResourceLoader resourceLoader, ObjectProvider<DataSource> dataSource,
 				@FlywayDataSource ObjectProvider<DataSource> flywayDataSource,
 				ObjectProvider<FlywayMigrationStrategy> migrationStrategy,
-				ObjectProvider<FlywayCallback[]> flywayCallbacks) {
+				ObjectProvider<List<FlywayCallback>> flywayCallbacks) {
 			this.properties = properties;
 			this.resourceLoader = resourceLoader;
 			this.dataSource = dataSource.getIfUnique();
 			this.flywayDataSource = flywayDataSource.getIfAvailable();
 			this.migrationStrategy = migrationStrategy.getIfAvailable();
-			this.flywayCallbacks = flywayCallbacks.getIfAvailable();
+			this.flywayCallbacks = flywayCallbacks
+					.getIfAvailable(() -> Collections.emptyList());
 		}
 
 		@PostConstruct
@@ -146,9 +148,8 @@ public class FlywayAutoConfiguration {
 			else {
 				flyway.setDataSource(this.dataSource);
 			}
-			if (this.flywayCallbacks != null && this.flywayCallbacks.length > 0) {
-				flyway.setCallbacks(this.flywayCallbacks);
-			}
+			flyway.setCallbacks(this.flywayCallbacks
+					.toArray(new FlywayCallback[this.flywayCallbacks.size()]));
 			flyway.setLocations(this.properties.getLocations().toArray(new String[0]));
 			return flyway;
 		}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/flyway/FlywayAutoConfigurationTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.autoconfigure.flyway;
 
+import java.sql.Connection;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
@@ -25,13 +26,14 @@ import javax.sql.DataSource;
 
 import org.flywaydb.core.Flyway;
 import org.flywaydb.core.api.MigrationVersion;
-import org.flywaydb.core.api.callback.BaseFlywayCallback;
+import org.flywaydb.core.api.callback.FlywayCallback;
 import org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
+import org.mockito.InOrder;
 
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration;
@@ -44,12 +46,16 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
 import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
 import org.springframework.stereotype.Component;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link FlywayAutoConfiguration}.
@@ -204,16 +210,6 @@ public class FlywayAutoConfigurationTests {
 		assertThat(initializer.getOrder()).isEqualTo(Ordered.HIGHEST_PRECEDENCE);
 	}
 
-	@Test
-	public void customFlywayCallback() throws Exception {
-		registerAndRefresh(EmbeddedDataSourceConfiguration.class,
-				FlywayAutoConfiguration.class, PropertyPlaceholderAutoConfiguration.class,
-				MockOneFlywayCallback.class, MockTwoFlywayCallback.class);
-		assertThat(this.context.getBean(Flyway.class)).isNotNull();
-		this.context.getBean(MockOneFlywayCallback.class).assertCalled();
-		this.context.getBean(MockTwoFlywayCallback.class).assertCalled();
-	}
-
 	@Test
 	public void customFlywayWithJpa() throws Exception {
 		registerAndRefresh(CustomFlywayWithJpaConfiguration.class,
@@ -258,6 +254,23 @@ public class FlywayAutoConfigurationTests {
 				"classpath:db/vendors/h2", "classpath:db/changelog");
 	}
 
+	@Test
+	public void callbacksAreConfiguredAndOrdered() throws Exception {
+		registerAndRefresh(EmbeddedDataSourceConfiguration.class,
+				FlywayAutoConfiguration.class, PropertyPlaceholderAutoConfiguration.class,
+				CallbackConfiguration.class);
+		assertThat(this.context.getBeansOfType(Flyway.class)).hasSize(1);
+		Flyway flyway = this.context.getBean(Flyway.class);
+		FlywayCallback callbackOne = this.context.getBean("callbackOne",
+				FlywayCallback.class);
+		FlywayCallback callbackTwo = this.context.getBean("callbackTwo",
+				FlywayCallback.class);
+		assertThat(flyway.getCallbacks()).containsExactly(callbackTwo, callbackOne);
+		InOrder orderedCallbacks = inOrder(callbackOne, callbackTwo);
+		orderedCallbacks.verify(callbackTwo).beforeMigrate(any(Connection.class));
+		orderedCallbacks.verify(callbackOne).beforeMigrate(any(Connection.class));
+	}
+
 	private void registerAndRefresh(Class<?>... annotatedClasses) {
 		this.context.register(annotatedClasses);
 		this.context.refresh();
@@ -337,34 +350,21 @@ public class FlywayAutoConfigurationTests {
 
 	}
 
-	@Component
-	protected static class MockOneFlywayCallback
-			extends BaseFlywayCallback {
-
-		private boolean called = false;
-
-		public MockOneFlywayCallback() {
-			this.called = true;
-		}
+	@Configuration
+	static class CallbackConfiguration {
 
-		public void assertCalled() {
-			assertThat(this.called).isTrue();
+		@Bean
+		@Order(1)
+		public FlywayCallback callbackOne() {
+			return mock(FlywayCallback.class);
 		}
-	}
-
-	@Component
-	protected static class MockTwoFlywayCallback
-			extends BaseFlywayCallback {
-
-		private boolean called = false;
 
-		public MockTwoFlywayCallback() {
-			this.called = true;
+		@Bean
+		@Order(0)
+		public FlywayCallback callbackTwo() {
+			return mock(FlywayCallback.class);
 		}
 
-		public void assertCalled() {
-			assertThat(this.called).isTrue();
-		}
 	}
 
 }

spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -1952,8 +1952,12 @@ Boot will call `Flyway.migrate()` to perform the database migration. If you woul
 more control, provide a `@Bean` that implements
 {sc-spring-boot-autoconfigure}/flyway/FlywayMigrationStrategy.{sc-ext}[`FlywayMigrationStrategy`].
 
-TIP: If you want to make use of http://flywaydb.org/documentation/callbacks.html[Flyway
-callbacks], those scripts should also live in the `classpath:db/migration` folder.
+Flyway supports SQL and Java http://flywaydb.org/documentation/callbacks.html[callbacks].
+To use SQL-based callbacks, place the callback scripts in the `classpath:db/migration`
+folder. To use Java-based callbacks, create one or more beans that implement
+`FlywayCallback` or, preferably, extend `BaseFlywayCallback`. Any such beans will be
+automatically registered with `Flyway`. They can be ordered using `@Order` or by
+implementing `Ordered`.
 
 By default Flyway will autowire the (`@Primary`) `DataSource` in your context and
 use that for migrations. If you like to use a different `DataSource` you can create