Update Liquibase and Flyway docs and test other changelog formats

Closes gh-5741

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/liquibase/LiquibaseAutoConfigurationTests.java

@@ -42,6 +42,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link LiquibaseAutoConfiguration}.
  *
  * @author Marcel Overdijk
+ * @author Andy Wilkinson
  */
 public class LiquibaseAutoConfigurationTests {
 
@@ -90,7 +91,7 @@ public class LiquibaseAutoConfigurationTests {
 	}
 
 	@Test
-	public void testOverrideChangeLog() throws Exception {
+	public void testXmlChangeLog() throws Exception {
 		EnvironmentTestUtils.addEnvironment(this.context,
 				"liquibase.change-log:classpath:/db/changelog/db.changelog-override.xml");
 		this.context.register(EmbeddedDataSourceConfiguration.class,
@@ -102,6 +103,32 @@ public class LiquibaseAutoConfigurationTests {
 				.isEqualTo("classpath:/db/changelog/db.changelog-override.xml");
 	}
 
+	@Test
+	public void testJsonChangeLog() throws Exception {
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"liquibase.change-log:classpath:/db/changelog/db.changelog-override.json");
+		this.context.register(EmbeddedDataSourceConfiguration.class,
+				LiquibaseAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		this.context.refresh();
+		SpringLiquibase liquibase = this.context.getBean(SpringLiquibase.class);
+		assertThat(liquibase.getChangeLog())
+				.isEqualTo("classpath:/db/changelog/db.changelog-override.json");
+	}
+
+	@Test
+	public void testSqlChangeLog() throws Exception {
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"liquibase.change-log:classpath:/db/changelog/db.changelog-override.sql");
+		this.context.register(EmbeddedDataSourceConfiguration.class,
+				LiquibaseAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		this.context.refresh();
+		SpringLiquibase liquibase = this.context.getBean(SpringLiquibase.class);
+		assertThat(liquibase.getChangeLog())
+				.isEqualTo("classpath:/db/changelog/db.changelog-override.sql");
+	}
+
 	@Test
 	public void testOverrideContexts() throws Exception {
 		EnvironmentTestUtils.addEnvironment(this.context,

spring-boot-autoconfigure/src/test/resources/db/changelog/db.changelog-override.json

@@ -0,0 +1,39 @@
+{
+    "databaseChangeLog": [
+        {
+            "changeSet": {
+                "author": "awilkinson",
+                "id": "1",
+                "changes": [
+                    {
+                        "createTable": {
+                            "tableName": "customer",
+                            "columns": [
+                                {
+                                    "column": {
+                                       "name": "id",
+                                        "type": "int",
+                                        "autoIncrement": true,
+                                        "constraints": {
+                                            "nullable": false,
+                                            "primaryKey": true
+                                        },
+                                    }
+                                },
+                                {
+                                    "column": {
+                                       "name": "name",
+                                        "type": "varchar(50)",
+                                        "constraints": {
+                                            "nullable": false
+                                        }
+                                    }
+                                }
+                            ],
+                        }
+                    }
+                ]
+            }
+        }
+    ]
+}

spring-boot-autoconfigure/src/test/resources/db/changelog/db.changelog-override.sql

@@ -0,0 +1,8 @@
+--liquibase formatted sql
+
+--changeset author:awilkinson
+
+CREATE TABLE customer (
+    id int AUTO_INCREMENT NOT NULL PRIMARY KEY,
+    name varchar(50) NOT NULL
+);

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

@@ -1847,11 +1847,9 @@ initialization explicitly using `spring.batch.initializer.enabled=false`.
 
 
 [[howto-use-a-higher-level-database-migration-tool]]
-=== Use a higher level database migration tool
-Spring Boot works fine with higher level migration tools http://flywaydb.org/[Flyway]
-(SQL-based) and http://www.liquibase.org/[Liquibase] (XML). In general we prefer
-Flyway because it is easier on the eyes, and it isn't very common to need platform
-independence: usually only one or at most couple of platforms is needed.
+=== Use a higher-level database migration tool
+Spring Boot supports two higher-level migration tools: http://flywaydb.org/[Flyway]
+and http://www.liquibase.org/[Liquibase].
 
 [[howto-execute-flyway-database-migrations-on-startup]]
 ==== Execute Flyway database migrations on startup
@@ -1890,12 +1888,15 @@ To automatically run Liquibase database migrations on startup, add the
 `org.liquibase:liquibase-core` to your classpath.
 
 The master change log is by default read from `db/changelog/db.changelog-master.yaml` but
-can be set using `liquibase.change-log`. See
+can be set using `liquibase.change-log`. In addition to YAML, Liquibase also supports
+JSON, XML, and SQL change log formats.
+
+See
 {sc-spring-boot-autoconfigure}/liquibase/LiquibaseProperties.{sc-ext}[`LiquibaseProperties`]
 for details of available settings like contexts, default schema etc.
 
-There is a {github-code}/spring-boot-samples/spring-boot-sample-liquibase[Liquibase sample] so
-you can see how to set things up.
+There is a {github-code}/spring-boot-samples/spring-boot-sample-liquibase[Liquibase sample]
+so you can see how to set things up.