### Question:
DoublePreference { public boolean isSet() { return mLongPreference.isSet(); } DoublePreference(SharedPreferences preferences, String key);  DoublePreference(SharedPreferences preferences, String key, double defaultValue); double get(); boolean isSet(); void set(double value); void delete(); static final double DEFAULT_VALUE_VALUE; }### Answer:
@Test public void expect_Preference_NotTo_BeSet() throws Exception { assertFalse(mPreference.isSet()); }