Add TransactionManager only on single DataSource

Update auto-configuration logic so that a `DataSourceTransactionManager`
is only added when there is a single candidate DataSource bean.

See gh-6449

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/DataSourceTransactionManagerAutoConfiguration.java

@@ -20,9 +20,9 @@ import javax.sql.DataSource;
 
 import org.springframework.boot.autoconfigure.AutoConfigureOrder;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandidate;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
@@ -46,7 +46,7 @@ import org.springframework.transaction.annotation.EnableTransactionManagement;
 public class DataSourceTransactionManagerAutoConfiguration {
 
 	@Configuration
-	@ConditionalOnBean(DataSource.class)
+	@ConditionalOnSingleCandidate(DataSource.class)
 	static class DataSourceTransactionManagerConfiguration {
 
 		private final DataSource dataSource;

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/DataSourceTransactionManagerAutoConfigurationTests.java

@@ -36,6 +36,7 @@ import static org.mockito.Mockito.mock;
  *
  * @author Dave Syer
  * @author Stephane Nicoll
+ * @author Kazuki Shimizu
  */
 public class DataSourceTransactionManagerAutoConfigurationTests {
 
@@ -84,6 +85,27 @@ public class DataSourceTransactionManagerAutoConfigurationTests {
 				.isEqualTo(this.context.getBean("myTransactionManager"));
 	}
 
+	@Test
+	public void testMultiDataSource() throws Exception {
+		this.context.register(MultiDataSourceConfiguration.class,
+				DataSourceTransactionManagerAutoConfiguration.class);
+		this.context.refresh();
+		assertThat(this.context.getBeansOfType(PlatformTransactionManager.class))
+				.isEmpty();
+		assertThat(this.context.getBean(AbstractTransactionManagementConfiguration.class))
+				.isNotNull();
+	}
+
+	@Test
+	public void testMultiDataSourceUsingPrimary() throws Exception {
+		this.context.register(MultiDataSourceUsingPrimaryConfiguration.class,
+				DataSourceTransactionManagerAutoConfiguration.class);
+		this.context.refresh();
+		assertThat(this.context.getBean(DataSourceTransactionManager.class)).isNotNull();
+		assertThat(this.context.getBean(AbstractTransactionManagementConfiguration.class))
+				.isNotNull();
+	}
+
 	@EnableTransactionManagement
 	protected static class SwitchTransactionsOn {
 

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/MultiDataSourceConfiguration.java

+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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.boot.autoconfigure.jdbc;
+
+import javax.sql.DataSource;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Configuration for multiple {@link DataSource}.
+ *
+ * @author Phillip Webb
+ * @author Kazuki Shimizu
+ */
+@Configuration
+class MultiDataSourceConfiguration {
+
+	@Bean
+	public DataSource test1DataSource() {
+		return new TestDataSource("test1");
+	}
+
+	@Bean
+	public DataSource test2DataSource() {
+		return new TestDataSource("test2");
+	}
+
+}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/MultiDataSourceUsingPrimaryConfiguration.java

+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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.boot.autoconfigure.jdbc;
+
+import javax.sql.DataSource;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
+
+/**
+ * Configuration for multiple {@link DataSource} (one being {@code @Primary}.
+ *
+ * @author Phillip Webb
+ * @author Kazuki Shimizu
+ */
+@Configuration
+class MultiDataSourceUsingPrimaryConfiguration {
+
+	@Bean
+	@Primary
+	public DataSource test1DataSource() {
+		return new TestDataSource("test1");
+	}
+
+	@Bean
+	public DataSource test2DataSource() {
+		return new TestDataSource("test2");
+	}
+
+}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/TestDataSource.java

+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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.boot.autoconfigure.jdbc;
+
+import org.apache.commons.dbcp.BasicDataSource;
+
+/**
+ * {@link BasicDataSource} used for testing.
+ *
+ * @author Phillip Webb
+ * @author Kazuki Shimizu
+ */
+public class TestDataSource extends BasicDataSource {
+
+	public TestDataSource(String name) {
+		setDriverClassName("org.hsqldb.jdbcDriver");
+		setUrl("jdbc:hsqldb:target/" + name);
+		setUsername("sa");
+	}
+
+}