• JUnit4的ClassRunner
• MockMvc直接对接口发起请求
• 桥接ibatis的bean
• Web到App的路由
• 后记

在公司维护的项目使用的框架很老（内部自研，基于Spring2实现的），单元测试框架使用的JUnit3。日常工作开发调试和自测两种办法：启动服务（weblogic，要打包启动，慢）、单元测试（较快，调试方便）。但老的写单测实在是很繁琐：先继承一个单元测试基类，覆盖其中获取配置文件方法（相当于配置context文件），再在另外两个配置文件中修改（与业务耦合的很紧），然后开始从context中getBean，然后你的准备工作终于做好了可以开始测试了。尤其对于新同事，有人指导还行，没有的话简直抓瞎（当然如果深入了解一下，也是能轻易搞定的，比如我哈哈哈）。思来想去决定：controller的单测，可以简化步骤（比如获取controller bean然后再调用对应方法这一步）；加入自动依赖注入，就像使用@Autowired一样（当前项目中还是使用的全XML配置方式）；将配置集中起来一个地方管理（使用注解）；升级到JUnit4.12。

JUnit4的ClassRunner

基于JUnit4的扩展，主要是利用其提供的ClassRunner，JUnit4.12默认的是BlockJUnit4ClassRunner，于是我们扩展该类，看看能在这里做点什么。

首先来看必须覆盖的构造器，构造参数clazz就是当前测试类的class。除了调用父类构造器，在此处还加了一步Pafa3TestContext.initContext，初始化Ioc容器，以及保存一些测试时需要的上下文信息。

然后注意createTest这个方法，事实上JUnit会根据测试class生成对应的实例。之前说过还实现了自动DI，那么很显然这一步在生成instance之后做再合适不过了，具体就是prepareAutoInject方法，至此自动DI已经实现，在测试类里@AutoInject private SomeController controller就可以直接获取到bean了，当然也提供了可以根据id获取bean。

public class Pafa3Junit4ClassRunner extends BlockJUnit4ClassRunner {public Pafa3Junit4ClassRunner(Class<?> clazz) throws Exception {super(clazz);Pafa3TestContext.initContext(getTestClass().getJavaClass());}@Overrideprotected Object createTest() throws Exception {Object instance = super.createTest();prepareAutoInject(instance);return instance;}private void prepareAutoInject(Object instance) throws IllegalAccessException {TestClass testClass = getTestClass();List<FrameworkField> frameworkFields = testClass.getAnnotatedFields(AutoInject.class);for (FrameworkField frameworkField : frameworkFields) {Object bean;String beanName = frameworkField.getAnnotation(AutoInject.class).value();if (!"".equals(beanName)) {bean = Pafa3TestContext.getContext().getBean(beanName);} else {Class<?> beanType = frameworkField.getType();Map beansOfType = Pafa3TestContext.getContext().getBeansOfType(beanType, true, true);Iterator it = beansOfType.values().iterator();if (it.hasNext()) {bean = it.next();} else {throw new NoSuchBeanDefinitionException(beanType, "no bean type found");}}Field field = frameworkField.getField();field.setAccessible(true);field.set(instance, bean);}}
}

public class Pafa3TestContext {private static ApplicationContext context;private static String[] contextLocations;private static String[] sqlConfigLocations;private static Class<?> clazz;private Pafa3TestContext() {}public static void initContext(Class<?> clazz) {Pafa3TestContext.clazz = clazz;initConfigLocations();initContext();}public static ApplicationContext getContext() {return context;}public static String[] getContextLocations() {return contextLocations;}public static String[] getSqlConfigLocations() {return sqlConfigLocations;}private static void initConfigLocations() {ContextLocations annotation = clazz.getAnnotation(ContextLocations.class);if (annotation == null) {throw new IllegalStateException("test class should be annotated with ContextLocations");}sqlConfigLocations = annotation.sqlMap();String[] locations = annotation.context();int len = locations.length;// 业务定制的，为了少写俩，直接先写死吧contextLocations = Arrays.copyOf(locations, len + 2); contextLocations[len] = "classpath:biz-context.xml";contextLocations[len + 1] = "classpath:common-context.xml";}private static void initContext() {if (context == null) {synchronized (Pafa3TestContext.class) {if (context == null) {context = new ClassPathXmlApplicationContext(getContextLocations());}}}}
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Inherited
public @interface ContextLocations {String[] context();String[] sqlMap() default {};}@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
@Inherited
public @interface AutoInject {String value() default "";
}

MockMvc直接对接口发起请求

原来对controller的测试是要先获取这个controller的bean，然后调用接口实际对应的方法。这里其实复杂了，因为bean都是同一个类型的，获取哪一个并没有区别。如果有给定接口，实际已经得到了实际要调用的方法，这个对应关系，也是定义在一个MethodNameResolver类型的bean里的，显然可以从我们的Pafa3TestContext里获取到（因为这时候已经初始化好了）。

public class MockMvcResult {private ModelAndView modelAndView;private String content;public MockMvcResult(ModelAndView modelAndView, String content) {this.modelAndView = modelAndView;this.content = content;}public Object getModel() {return modelAndView == null ? null : modelAndView.getModel();}public Object getView() {return modelAndView == null ? null : modelAndView.getView();}public String getContentAsString() {return content;}
}public interface MockMvc {MockMvcResult request() throws Exception;
}public class StandaloneMockMvc implements MockMvc {private final ApplicationContext context = Pafa3TestContext.getContext();private final String url;private final MockHttpServletRequest request;private final MockHttpServletResponse response;public StandaloneMockMvc(StandaloneMockMvcBuilder builder) {this.url = builder.getUrl();this.request = builder.getRequest();this.response = builder.getResponse();}@Overridepublic MockMvcResult request() throws Exception {Map beanMap = context.getBeansOfType(MethodNameResolver.class, true, true);if (beanMap == null || beanMap.isEmpty()) {throw new NoSuchBeanDefinitionException(MethodNameResolver.class, "ensure add the web context file");}String methodName = null;Iterator it = beanMap.values().iterator();while (it.hasNext() && methodName == null) {MethodNameResolver resolver = (MethodNameResolver) it.next();try {methodName = resolver.getHandlerMethodName(request);} catch (NoSuchRequestHandlingMethodException ignored) {}}if (methodName == null) {throw new NoSuchRequestHandlingMethodException(request);}Object controller = context.getBean(url);return dispatchRequest(methodName, controller);}private MockMvcResult dispatchRequest(String methodName, Object controller) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {Method handleMethod = controller.getClass().getDeclaredMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);Object result = handleMethod.invoke(controller, request, response);if (result == null) {return new MockMvcResult(null, response.getContentAsString());}if (ModelAndView.class.isAssignableFrom(result.getClass())) {return new MockMvcResult((ModelAndView) result, null);}return null;}
}public class StandaloneMockMvcBuilder {private static final String SESSION_USER = "userinformation";private final String url;private final String method;private final MockHttpServletRequest request;private final MockHttpServletResponse response;public StandaloneMockMvcBuilder(String url) {this("GET", url);}public StandaloneMockMvcBuilder(String method, String url) {this.url = url;this.method = method;this.request = new MockHttpServletRequest(null, this.method, this.url);this.response = new MockHttpServletResponse();}public StandaloneMockMvcBuilder addParameter(String name, String value) {request.addParameter(name, value);return this;}public String getUrl() {return url;}public String getMethod() {return method;}public MockHttpServletRequest getRequest() {return request;}public MockHttpServletResponse getResponse() {return response;}public StandaloneMockMvcBuilder withUser(String uid) {UserInformationVO user = new UserInformationVO();user.setUID(uid);return withUser(user);}public StandaloneMockMvcBuilder withUser(UserInformationVO user) {request.getSession().setAttribute(SESSION_USER, user);return this;}public StandaloneMockMvc build() {return new StandaloneMockMvc(this);}
}

至此，我们可以直接构造对应的URL以及相关参数，使用MockMvc发起请求等待结果了。

桥接ibatis的bean

以上两点完成后，还差一个连接数据库的bean。项目中使用的是ibatis，读取的sqlmap是定义在一个sqlmap-config.xml里，该配置包含所有的sqlmap（按功能模块分的），然后由SqlMapClientFactoryBean来读取sqlmap-config.xml。由于配置都集中管理在ContextLocations注解里了，所以这里也需要重新实现，用了一个小聪明，直接根据配置的sqlMapConfig生成一个XML内容交给SqlMapClientFactoryBean去读取。

public class SimpleSqlMapClientFactoryBean extends SqlMapClientFactoryBean {@Overridepublic void afterPropertiesSet() throws IOException {Resource configLocation = getSqlConfigResource();super.setConfigLocation(configLocation);super.afterPropertiesSet();}private Resource getSqlConfigResource() {String[] configLocations = Pafa3TestContext.getSqlConfigLocations();if (configLocations == null || configLocations.length == 0) {return new ClassPathResource("sqlmap-config.xml");}return builtXMLResource(configLocations);}private Resource builtXMLResource(String[] configLocations) {final String xmlAsString = buildSqlMapConfigContent(configLocations);return new AbstractResource() {@Overridepublic InputStream getInputStream() throws IOException {return new ByteArrayInputStream(xmlAsString.getBytes("UTF-8"));}@Overridepublic String getDescription() {return "XML built as string: " + xmlAsString;}};}private String buildSqlMapConfigContent(String[] configLocations) {Document document = DocumentHelper.createDocument();document.setXMLEncoding("UTF-8");document.addDocType("sqlMapConfig", "-//iBATIS.com//DTD SQL Map Config 2.0//EN", "http://www.ibatis.com/dtd/sql-map-config-2.dtd");Element sqlMapConfig = document.addElement("sqlMapConfig");Element setting = sqlMapConfig.addElement("settings");setting.addAttribute("cacheModelsEnabled", "true");setting.addAttribute("enhancementEnabled", "false");setting.addAttribute("lazyLoadingEnabled", "false");setting.addAttribute("maxRequests", "3000");setting.addAttribute("maxSessions", "3000");setting.addAttribute("maxTransactions", "3000");setting.addAttribute("useStatementNamespaces", "true");for (String location : configLocations) {Element sqlMap = sqlMapConfig.addElement("sqlMap");sqlMap.addAttribute("resource", location);}return document.asXML();}
}

Web到App的路由

项目是分层部署的，分为了Web（DMZ区）和App（内网）两层，前者就是controller所在，然后远程调用App层的Action（通过EJB）。在本地单元测试，显然不会去构造一个EJB容器环境，而是直接通过本地同一个JVM调用即可（项目中调用的bean的名字是写死的），于是实现一个本地的ApplicationController。

public class AppControllerFactoryBean implements FactoryBean {private ApplicationController proxy;@Overridepublic Object getObject() throws Exception {if (proxy == null) {proxy = getProxy();}return proxy;}@Overridepublic Class getObjectType() {return proxy != null ? proxy.getClass() : ApplicationController.class;}@Overridepublic boolean isSingleton() {return true;}private ApplicationController getProxy() {return (ApplicationController) Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),new Class[]{ApplicationController.class}, new LocalProxyAppControllerInvocationHandler());}
}public class LocalProxyAppControllerInvocationHandler implements InvocationHandler {@Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {String methodName = method.getName();Class<?>[] parameterTypes = method.getParameterTypes();if (method.getDeclaringClass() == Object.class) {throw new UnsupportedOperationException("unsupported method: " + method);}if ("toString".equals(methodName) && parameterTypes.length == 0) {return "proxy of ApplicationController";}if ("hashCode".equals(methodName) && parameterTypes.length == 0) {return 1;}if ("equals".equals(methodName) && parameterTypes.length == 1) {return Boolean.FALSE;}if (args.length != 1 || !(args[0] instanceof ServiceRequest)) {throw new IllegalArgumentException("arguments length not 1 or not type of ServiceRequest");}return invokeLocal((ServiceRequest) args[0]);}private Object invokeLocal(ServiceRequest request) throws BusinessServiceException {String beanName = request.getRequestedServiceID();Action action = (Action) Pafa3TestContext.getContext().getBean(beanName);return action.perform(request);}
}

写完之后发现，似乎不用动态代理，直接实现ApplicationController就行了= =||。不过鉴于都写出来了，暂时先用着吧。主要是提醒看代码的同志，toString, equals, hashCode三个方法，在动态代理时也是会被代理的。

后记

大功告成，现在写单元测试的效率比之前提高的简直不要太多。终于不用东配置一下西添加一下了（而且有两个还是重复的），对团队的提升自我感觉还是比较多的。但是有啥借鉴的么？我觉得没啥，都是被老项目老框架逼出来的轮子，毕竟新框架直接上Spring的test即可，功能强大好用。顺便吐槽一下公司：老项目难升级情有可原，但是2017年新启动的项目，还有必要继续jdk1.6 + weblogic + spring3.1吗？