### Question:
PrimitiveLongIntKeyValueArray { public long[] keys() { return Arrays.copyOfRange( naturalKeys, 0, size ); } PrimitiveLongIntKeyValueArray( int initialCapacity, double growthFactor );  PrimitiveLongIntKeyValueArray( int initialCapacity );  PrimitiveLongIntKeyValueArray(); int capacity(); double growthFactor(); void ensureCapacity( int newCapacity ); int size(); int getOrDefault( long key, int defaultValue ); boolean putIfAbsent( long key, int value ); void reset( int newCapacity ); long[] keys(); static final int DEFAULT_INITIAL_CAPACITY; static final double DEFAULT_GROWTH_FACTOR; }### Answer:
@Test void testKeys() { PrimitiveLongIntKeyValueArray map = new PrimitiveLongIntKeyValueArray(); map.putIfAbsent( 1, 100 ); map.putIfAbsent( 2, 200 ); map.putIfAbsent( 3, 300 ); map.putIfAbsent( 2, 200 ); map.putIfAbsent( 3, 300 ); map.putIfAbsent( 8, 800 ); map.putIfAbsent( 7, 700 ); map.putIfAbsent( 6, 600 ); map.putIfAbsent( 5, 500 ); assertThat( map.size(), equalTo( 7 ) ); assertThat( map.keys(), equalTo( new long[]{1, 2, 3, 8, 7, 6, 5} ) ); }