How to use espresso to press a AlertDialog button

I want to press below button using Espresso, but I'm not sure how. Should I get the resource-id? Or how to set an ID to the AlertDialog??

@RunWith(AndroidJUnit4.class)
public class ApplicationTest {

@Rule
public ActivityTestRule<LoadingActivity> mActivityRule =
        new ActivityTestRule<>(LoadingActivity.class);

@Test
public void loginClickMarker() {
//Doesn't work:
    onView(withText("GA NAAR INSTELLINGEN")).perform(click());
}
}

public class PopupDialog {

public static void showGPSIsDisabled(Context context, String msg, final PopupDialogCallback popupDialogCallback) {
    new AlertDialog.Builder(context)
            .setTitle(context.getString(R.string.location_turned_off))
            .setMessage(msg)
            .setPositiveButton(context.getString(R.string.go_to_settings), new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                    popupDialogCallback.hasClicked();
                }
            }).show();
}
}

android.support.test.espresso.NoMatchingViewException: No views in hierarchy found matching: with text: is "GA NAAR INSTELLINGEN"

According to StackOverflow similar issue: Check if a dialog is displayed with Espresso

You should change your code from:

onView(withText("GA NAAR INSTELLINGEN")).perform(click());

to

onView(withText("GA NAAR INSTELLINGEN"))
    .inRoot(isDialog())                 
    .check(matches(isDisplayed()))      
    .perform(click());  
            

If it won't work, don't bother to use long with Espresso another great Google's instrumentation test called uiatomator.

Check: http://qathread.blogspot.com/2015/05/espresso-uiautomator-perfect-tandem.html

Example code:

// Initialize UiDevice instance
UiDevice uiDevice = UiDevice.getInstance(InstrumentationRegistry.getInstrumentation());

// Search for correct button in the dialog.
UiObject button = uiDevice.findObject(new UiSelector().text("GA NAAR INSTELLINGEN"));
if (button.exists() && button.isEnabled()) {
    button.click();
}