Providing test data for SharedPreferences for Robolectric

The accepted answer which I have up voted is right of course. Things have changed slightly if you are using Robolectric 3

 SharedPreferences sharedPreferences =
     RuntimeEnvironment.application.getSharedPreferences(
         "you_custom_pref_name", Context.MODE_PRIVATE);

You can then add a preference as usual

 sharedPreferences.edit().putBoolean(
    activity.getString(R.string.pref_somepref), true).commit();

Robolectric 3.1 SNAPSHOT solution that works for me... and may work for you

    Context context = RuntimeEnvironment.application.getApplicationContext();
    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
    sharedPreferences.edit().putBoolean("useOnlyOnWifi", false).commit();

I use this snippet of code for only testing on wifi

Found out how - seems so obvious now!

For those who are interested, you just get the sharedPreferences, and populate it with the required data.

SharedPreferences sharedPreferences = ShadowPreferenceManager.getDefaultSharedPreferences(Robolectric.application.getApplicationContext());
sharedPreferences.edit().putString("testId", "12345").commit();

If you have a custom SharedPreferences, you should be able to do this (haven't really tested properly, but should also work)

SharedPreferences sharedPreferences = Robolectric.application.getSharedPreferences("you_custom_pref_name", Context.MODE_PRIVATE);
sharedPreferences.edit().putString("testId", "12345").commit();

Hope this has helped someone :)