### Question:
MutableLinearProbeLongHashSet extends AbstractLinearProbeLongHashSet implements MutableLongSet, Resource { @Override public void clear() { ++modCount; copyIfFrozen(); memory.clear(); hasZero = false; hasOne = false; elementsInMemory = 0; removals = 0; } MutableLinearProbeLongHashSet( MemoryAllocator allocator ); @Override boolean add( long element ); @Override boolean addAll( long... elements ); @Override boolean addAll( LongIterable elements ); @Override boolean remove( long element ); @Override boolean removeAll( LongIterable elements ); @Override boolean removeAll( long... elements ); @Override boolean retainAll( LongIterable elements ); @Override boolean retainAll( long... source ); @Override void clear(); @Override MutableLongIterator longIterator(); @Override void close(); @Override MutableLongSet tap( LongProcedure procedure ); @Override MutableLongSet with( long element ); @Override MutableLongSet without( long element ); @Override MutableLongSet withAll( LongIterable elements ); @Override MutableLongSet withoutAll( LongIterable elements ); @Override MutableLongSet asUnmodifiable(); @Override MutableLongSet asSynchronized(); @Override LongSet freeze(); @Override ImmutableLongSet toImmutable();  }### Answer:
@Test void clear() { set.addAll( 1, 2, 3 ); assertEquals( 3, set.size() ); set.clear(); assertEquals( 0, set.size() ); set.clear(); assertEquals( 0, set.size() ); set.addAll( 4, 5, 6 ); assertEquals( 3, set.size() ); set.clear(); assertEquals( 0, set.size() ); }