How to mock a SharedPreferences using Mockito

So, because SharedPreferences comes from your context, it’s easy:

final SharedPreferences sharedPrefs = Mockito.mock(SharedPreferences.class);
final Context context = Mockito.mock(Context.class);
Mockito.when(context.getSharedPreferences(anyString(), anyInt())).thenReturn(sharedPrefs);

// no use context

for example, for getValidToken(Context context), the test could be:

@Before
public void before() throws Exception {
    this.sharedPrefs = Mockito.mock(SharedPreferences.class);
    this.context = Mockito.mock(Context.class);
    Mockito.when(context.getSharedPreferences(anyString(), anyInt())).thenReturn(sharedPrefs);
}

@Test
public void testGetValidToken() throws Exception {
    Mockito.when(sharedPrefs.getString(anyString(), anyString())).thenReturn("foobar");
    assertEquals("foobar", Auth.getValidToken(context));
    // maybe add some verify();
}