@Test
public void getAll() {

    String stringKey = String.class.getSimpleName().toLowerCase() + KEY_SUFFIX;
    String stringValue = "value";
    String booleanKey = boolean.class.getSimpleName().toLowerCase() + KEY_SUFFIX;
    preferences.edit()
            .putString(stringKey, stringValue)
            .putBoolean(booleanKey, true)
            .apply();
    Map<String, ?> all = preferences.getAll();
    Object str = all.get(stringKey);
    Object bool = all.get(booleanKey);
    assertEquals(str.getClass(), String.class);
    assertEquals(bool.getClass(), Boolean.class);
    assertEquals(str, stringValue);
    assertEquals(true, bool);
}