实现Guice下的单元测试中mybatis数据库操作的回滚.

在Spring中,提供了@transaction注解来在单元测试中,回滚数据库的操作,这样保证了单元测试的方法,不会对真实的数据库进行更新.从而更好地保持了各个单元测试方法的独立性.

在Guice中,并没有提供相应的机制. 我们可以通过自定义的BlockJUnit4ClassRunner继承子类来实现类似的功能.
代码如下:

import com.google.inject.Guice;import com.google.inject.Inject;import com.google.inject.Injector;import org.apache.ibatis.session.SqlSessionManager;import org.junit.runners.BlockJUnit4ClassRunner;import org.junit.runners.model.FrameworkMethod;import org.junit.runners.model.InitializationError;import org.junit.runners.model.Statement;public class MyBatisTestRollbackRunner extends BlockJUnit4ClassRunner {    private Injector injector;    @Inject    private SqlSessionManager sqlSessionManager;    public MyBatisTestRollbackRunner(final Class<?> clazz) throws InitializationError {        super(clazz);        MyBatisModuleFactory myBatisModuleFactory = new MyBatisModuleFactory(new ConfigurationFactory());        injector = Guice.createInjector(myBatisModuleFactory.get(clazz));        injector.injectMembers(this);    }    @Override    protected Statement methodInvoker(final FrameworkMethod method, final Object instance) {        return new Statement() {            @Override            public void evaluate() throws Throwable {                try {                    invokeMethodInNewSession(method, instance);                } finally {                    cleanupSession();                }            }        };    }    private void invokeMethodInNewSession(final FrameworkMethod method, final Object instance) throws Throwable {        sqlSessionManager.startManagedSession();        method.invokeExplosively(instance);    }    private void cleanupSession() {        try {            sqlSessionManager.rollback(true);        } finally {            sqlSessionManager.close();        }    }    @Override    protected Object createTest() throws Exception {        Object testClass = super.createTest();        injector.injectMembers(testClass);        return testClass;    }}import com.google.inject.name.Names;import org.apache.ibatis.transaction.jdbc.JdbcTransactionFactory;import org.junit.runners.model.InitializationError;import org.mybatis.guice.MyBatisModule;import org.mybatis.guice.datasource.builtin.PooledDataSourceProvider;import java.util.Arrays;public class MyBatisModuleFactory {    private final ConfigurationFactory configurationFactory;    public MyBatisModuleFactory(final ConfigurationFactory configurationFactory) {        this.configurationFactory = configurationFactory;    }    public MyBatisModule get(final Class<?> clazz) {        return new MyBatisModule() {            @Override            protected void initialize() {                bindDataSourceProviderType(PooledDataSourceProvider.class);                bindTransactionFactoryType(JdbcTransactionFactory.class);                addMapperClasses();            }            private void addMapperClasses() {                try {                    addMapperClasses(Arrays.asList(getAnnotatedMapperClasses(clazz)));                } catch (Throwable e) {                    throw new UnsupportedOperationException("can't add mapper classes");                }            }        };    }    private Class<?>[] getAnnotatedMapperClasses(final Class<?> clazz) throws InitializationError {        MapperClasses annotation = clazz.getAnnotation(MapperClasses.class);        if (annotation == null) {            throw new InitializationError(String.format("class '%s' must have a MapperClasses annotation", clazz.getName()));        }        return annotation.value();    }}

总体的实现思路.

• 在创建测试方法时,使用自定义的injector.这个通过重载createTest()实现.
• 在自定义的SqlSessionManager上执行测试方法.
  
  • 开启Session.
  • 执行测试方法.
  • 回滚Session.

• 另外,通过annotation的方式,将我们需要测试的Mapper类注册到injector中.这个在getAnnotatedMapperClasses方法中实现.

  例如,我们需要测试一个ConnectorMapper的Mapper类.那么使用以下的代码进行测试.

@RunWith(MyBatisTestRollbackRunner.class)@MapperClasses({ConnectorMapper.class})public class ConnectorMapperTest {    @Inject    ConnectorMapper connectorMapper;    //对ConnectorMapper的增删改查操作的测试方法    .....}