### Question:
BooleanValue extends Value { @Override Value not () { return !mValue ? cTrueStringValue : cFalseStringValue; } BooleanValue(boolean value);   BooleanValue(String text); @Override String toString();  }### Answer:
@Test public void testNot () { assertEquals ("false", mTrueValue.not ().toString ()); assertEquals ("true", mFalseValue.not ().toString ()); }