Fix @AutoConfigureTestDatabase imports

Update `@AutoConfigureTestDatabase` so that it always imports
`DataSourceAutoConfiguration`. Prior to this commit the annotation
could only be applied if something else also imported DataSource
auto-configuration.

Fixes gh-6897

spring-boot-test-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -39,7 +39,8 @@ org.springframework.boot.test.autoconfigure.restdocs.RestDocsAutoConfiguration
 
 # AutoConfigureTestDatabase auto-configuration imports
 org.springframework.boot.test.autoconfigure.orm.jpa.AutoConfigureTestDatabase=\
-org.springframework.boot.test.autoconfigure.orm.jpa.TestDatabaseAutoConfiguration
+org.springframework.boot.test.autoconfigure.orm.jpa.TestDatabaseAutoConfiguration,\
+org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration
 
 # AutoConfigureTestEntityManager auto-configuration imports
 org.springframework.boot.test.autoconfigure.orm.jpa.AutoConfigureTestEntityManager=\

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

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.test.autoconfigure.orm.jpa;
 
+import javax.sql.DataSource;
+
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -42,6 +44,7 @@ public class AutoConfigureTestDatabaseWithNoDatabaseIntegrationTests {
 	public void testContextLoades() throws Exception {
 		// gh-6897
 		assertThat(this.context).isNotNull();
+		assertThat(this.context.getBeanNamesForType(DataSource.class)).isNotEmpty();
 	}
 
 	@TestConfiguration