java - How to use Gson TypeAdapter with an object mocked by Mockito? -

i mock object passed gson via typeadapter this:

@runwith(mockitojunitrunner.class) public class sceneexportertest {  @test public void testwriter() {     list<sceneobject> sceneobjects = mocksceneobjects();     gson gson = new gsonbuilder().registertypeadapter(sceneobject.class, new sceneexporter()).create();      string s = gson.tojson(sceneobjects); //this method ends exception. }  private list<sceneobject> mocksceneobjects() {     list<sceneobject> sceneobjects = new linkedlist<>();     (int = 0; < 50; i++) {         sceneobjects.add(mocksceneobject(i));     }     return sceneobjects; }  private sceneobject mocksceneobject(int i) {     sceneobject sceneobject = mock(sceneobject.class);     //...     return sceneobject; }  } 

my type adapter:

public class sceneexporter extends typeadapter<sceneobject> {      @override     public void write(jsonwriter out, sceneobject value) throws ioexception {         out.name("position");         out.value(tovalue(value.getposition()));         out.name("scale");         out.value(tovalue(value.getscale()));         out.name("rotation");         out.value(tovalue(value.getrotation()));     }      @override     public sceneobject read(jsonreader in) throws ioexception {         return null;     } } 

but end such exception:

java.lang.unsupportedoperationexception: attempted serialize java.lang.class: com.editor.api.scene.objects.sceneobject. forgot register type adapter? 

scene object pretty heavy object , don't want instantinate within test. there possibility mock it? not use spies.

the runtime type of instance of sceneobject created in way: mock(sceneobject.class) sceneobject$mockitomock$<someid>.

the runtime type of instance of sceneobject created in way: new sceneobject() sceneobject.

so, when gson's typeadapterruntimetypewrapper looks registered typeadapter in context mocked object not find 1 because sceneexporter has been registered against sceneobject.class.

what saying mocked sceneobject not of type sceneobject (it sub class of sceneobject) hence gson not find bespoke type adapter.

if declare gson ...

gson gson = new gsonbuilder().registertypeadapter(mock(sceneobject.class).getclass(), new sceneexporter()).create(); 

... will find bespoke type adapter registration looks 'off' doesn't it? feels test-only specialisation.

if must mock sceneobject think you'll need register inheritance aware type adapter if doing support test case feels test-only limitation bleeding 'main' source tree. so, perhaps simplest solutions are:

• create real instances of sceneobject
• use mockito spy stub out specific sceneobject getters invoked in sceneexporter