Java 使用 Mockito 将参数模拟对象转换为另一个对象
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Casting a parameter mock object to another object using Mockito
提问by Rebane Lumes
I have a method to test, that begins following:
我有一种测试方法，从以下开始：
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) menuInfo;
contextString = adapter.getItem(info.position);
/.../
}
I would like to test it using Mockito, but if I declare menuInfo like this:
我想使用 Mockito 测试它，但如果我像这样声明 menuInfo：
@Mock ContextMenuInfo menuInfo
then I cannot compile the following statement:
那么我无法编译以下语句：
Mockito.when(menuInfo.position).thenReturn(1);
since it is not valid for ContextMenuInfoobject. I cannot declare my object as AdapterView.AdapterContextMenuInfoclass, since then I get an error during run time.
因为它对ContextMenuInfo对象无效。我不能将我的对象声明为AdapterView.AdapterContextMenuInfo类，因为我在运行时收到错误。
I know that in Mockito it is possible that a mock implements multiple interfaces, but the same does not apply to classes. How would it be possible to test the method I shown above?
我知道在 Mockito 中，一个模拟可能实现多个接口，但同样不适用于类。如何测试我上面显示的方法？
采纳答案by Jeff Bowman
Mockito works by using Java inheritanceto replace the implementations of methods on a class. However, it looks like positionis a fieldon AdapterContextMenuInfo, which means that Mockito can't mock it for you.
Mockito 的工作原理是使用 Java继承来替换类上方法的实现。然而，它看起来就像position是一个领域上AdapterContextMenuInfo，这意味着能的Mockito不嘲笑它。
Luckily, AdapterContextMenuInfo has a public constructor, so you don't have to mock it—you can just create one for the test and pass it into your method.
幸运的是，AdapterContextMenuInfo 有一个公共构造函数，因此您不必模拟它——您只需为测试创建一个并将其传递到您的方法中即可。
@Test public void contextMenuShouldWork() {
ContextMenuInfo info =
new AdapterView.AdapterContextMenuInfo(view, position, id);
systemUnderTest.onCreateContextMenu(menu, view, info);
/* assert success here */
}
If you're ever stuck in this pattern for a class that you can't directly mock or instantiate, consider creating a helper class that you canmock:
如果您在无法直接模拟或实例化的类中陷入这种模式，请考虑创建一个可以模拟的帮助类：
class MyHelper {
/** Used for testing. */
int getPositionFromContextMenuInfo(ContextMenuInfo info) {
return ((AdapterContextMenuInfo) info).position;
}
}
Now you can refactor your View to use that:
现在您可以重构您的视图以使用它：
public class MyActivity extends Activity {
/** visible for testing */
MyHelper helper = new MyHelper();
public void onCreateContextMenu(
ContextMenu menu, View v, ContextMenuInfo menuInfo) {
int position = helper.getPositionFromContextMenuInfo(menuInfo);
// ...
}
}
...and then mock the helperin your test.
...然后在您的测试中模拟助手。
/** This is only a good idea in a world where you can't instantiate the type. */
@Test public void contextMenuShouldWork() {
ContextMenuInfo info = getSomeInfoObjectYouCantChange();
MyHelper mockHelper = Mockito.mock(MyHelper.class);
when(mockHelper.getPositionFromContextMenu(info)).thenReturn(42);
systemUnderTest.helper = mockHelper;
systemUnderTest.onCreateContextMenu(menu, view, info);
/* assert success here */
}
There is one other option, involving a refactor:
还有另一种选择，涉及重构：
public class MyActivity extends Activity {
public void onCreateContextMenu(
ContextMenu menu, View v, ContextMenuInfo menuInfo) {
AdapterView.AdapterContextMenuInfo info =
(AdapterView.AdapterContextMenuInfo) menuInfo;
onCreateContextMenuImpl(info.position);
}
/** visible for testing */
void onCreateContextMenuImpl(int position) {
// the bulk of the code goes here
}
}
@Test public void contextMenuShouldWork() {
systemUnderTest.onCreateContextMenuImpl(position);
/* assert success here */
}
回答by Dawood ibn Kareem
Why don't you have a getter in AdapterView.AdapterContextMenuInfothat lets you write info.getPosition()? If you had that, then you could mock AdapterView.AdapterContextMenuInfo, stub getPosition(), then just pass the mock into the method that you're testing.
为什么你没有一个AdapterView.AdapterContextMenuInfo让你写作的吸气剂info.getPosition()？如果你有那个，那么你可以模拟AdapterView.AdapterContextMenuInfo，存根getPosition()，然后将模拟传递到你正在测试的方法中。
回答by jsphdnl
May be use mockito's extraInterfacesoption
可能使用 mockito 的extraInterfaces选项
@Mock(extraInterfaces=AdapterView.AdapterContextMenuInfo.class)
ContextMenuInfo menuInfo
and then mock it like
然后嘲笑它像
Mockito.doReturn(1).when((AdapterView.AdapterContextMenuInfo)menuInfo).position
