Java 如何模拟单例工厂的对象创建?
我试图效仿的例子是:Java 如何模拟单例工厂的对象创建?,java,unit-testing,powermock,powermockito,Java,Unit Testing,Powermock,Powermockito,我试图效仿的例子是: @PrepareForTest(X.class) public class XTest extends PowerMockTestCase { @Test public void test() { whenNew(MyClass.class).withNoArguments().thenThrow(new IOException("error message")); X x =
@PrepareForTest(X.class)
public class XTest extends PowerMockTestCase {
@Test
public void test() {
whenNew(MyClass.class).withNoArguments().thenThrow(new IOException("error message"));
X x = new X();
x.y(); // y is the method doing "new MyClass()"
..
}
}
我尝试进行单元测试的工厂类:
public final class LoadableBeanFactory implements ILoadableBeanFactory {
private static final class Loader {
private static final LoadableBeanFactory INSTANCE = new LoadableBeanFactory();
}
private LoadableBeanFactory() { }
public static @Nonnull LoadableBeanFactory getInstance() {
return Loader.INSTANCE;
}
public final @Nonnull <BeanT extends ILoadableBean> BeanT create(final Class<BeanT> beanClass) {
final BeanT optionBean;
try {
final Constructor<BeanT> ctor = beanClass.getConstructor();
optionBean = ctor.newInstance();
return beanClass.cast(optionBean);
} catch(Exception e) {
throw new IllegalArgumentException("Could not instantiate an instance of " + beanClass);
}
}
}
你为什么要这么做 如果将工厂封装在抽象(一个单独的类)中,那么可以通过构造函数注入工厂并模拟其创建方法
public class BeanFactory {
public <BeanT extends ILoadableBean> BeanT create(final Class<BeanT> beanClass) {
return LoadableBeanFactory.getInstance().create(beanClass);
}
}
然后你根本不需要PowerMock,你的设计真的很好。这是因为工厂通过反射实例化了你的bean,很可能与类加载有关,但我不熟悉mockito/PowerMock的这些低级方面。如果您只是返回一个
新的LoadableBean()
,它就会工作。请注意,您可以使用assertSame
检查参数是否引用相同的实例。这是一个很好的建议!我将重新调整我的代码库,以便在工厂中使用这种设计模式。
public class BeanFactory {
public <BeanT extends ILoadableBean> BeanT create(final Class<BeanT> beanClass) {
return LoadableBeanFactory.getInstance().create(beanClass);
}
}
public class SomeClass {
private final BeanFactory beanFactory;
public SomeClass(BeanFactory beanFactory) {
this.beanFactory= beanFactory;
}
public void doSth() {
beanFactory.create(...);
}
}