Small code, big test

I have this code in a controller of an MVC implementation:

public void execute() {
        try {
            String path = userSelectsFile(); 
            if ( path == null ) return; //Just returns if the user press "Cancel"

            //Load the data
            Collection<Info> infos = Infos.fromJSON(getInputReader(path));
            //Show the data in the interface
            new ShowTransformationsInTree(win(), infos, win().getTree()).execute();
        } catch (Exception e) {
            new ComplainAction(win(), "Unable to...blah, blah", e).execute();
        }
    }

To test this, I have to mock the user interface to show file dialog and make getInputReader method an abstract factory method.

So here goes the test:

/**
     * Mocks the LoadTransformationsAction so the factory method getReader returns a ByteInputStream
     */
    public class MockLoadTransformationsAction extends LoadTransformationsAction {
        //CONSTRUCTOR REMOVED FOR CLARITY.....

        @Override
        protected InputStreamReader getInputReader(String path) {
            assertEquals(FAKE_ABSOLUTE_PATH, path);
            return new InputStreamReader(
                    new ByteArrayInputStream(TestHelpers.createDataBytes());
        }
    }

    /**
     * Test the proper loading of the data.
     */
    @Test
    public void testLoadData(@Mocked final FileChooser anyChooser) {
        new Expectations() {{
            //Mocks the IntelliJ idea API
            FileChooser.chooseFile(null, null, null); result = new MyFakeVirtualFile(); //Returns a fixed path
        }};

        //Loads the data from the JSON file
        MainToolWin m = new FakeMainToolWin();
        LoadTransformationsAction action = new MockLoadTransformationsAction(
                m, new FakeProject(), new MockInputProgram());
        action.execute();

        //Test that the transformations are in the UI Tree
        DefaultTreeModel model = (DefaultTreeModel)m.getTree().getModel();
        assertEquals(2, model.getChildCount(model.getRoot()));
        assertEquals(3, model.getChildCount(model.getChild(model.getRoot(), 0)));
    }

QUESTIONS

Am I doing to much to test to little?

As you can see there are mock and facke objects all the way, so much mocking can make my test unreliable?

A better design can be proposed?