question: public void testQuantization ( ) throws Exception { Random random = random ( ) ; for ( int i = 0 ; i < 10000 ; i ++ ) { int encoded = random . nextInt ( ) ; if ( encoded < Geo3DUtil . MIN_ENCODED_VALUE ) { continue ; } if ( encoded > Geo3DUtil . MAX_ENCODED_VALUE ) { continue ; } double min = encoded * Geo3DUtil . DECODE ; double decoded = Geo3DUtil . decodeValueFloor ( encoded ) ; assertEquals ( min , decoded , 0.0D ) ; assertEquals ( encoded , Geo3DUtil . encodeValue ( decoded ) ) ; if ( encoded != Integer . MAX_VALUE ) { double max = min + Geo3DUtil . DECODE ; assertEquals ( max , Geo3DUtil . decodeValueFloor ( encoded + 1 ) , 0.0D ) ; assertEquals ( encoded + 1 , Geo3DUtil . encodeValue ( max ) ) ; double minEdge = Math . nextUp ( min ) ; double maxEdge = Math . nextDown ( max ) ; assertEquals ( encoded , Geo3DUtil . encodeValue ( minEdge ) ) ; assertEquals ( encoded , Geo3DUtil . encodeValue ( maxEdge ) ) ; long minBits = NumericUtils . doubleToSortableLong ( minEdge ) ; long maxBits = NumericUtils . doubleToSortableLong ( maxEdge ) ; for ( int j = 0 ; j < 100 ; j ++ ) { double value = NumericUtils . sortableLongToDouble ( TestUtil . nextLong ( random , minBits , maxBits ) ) ; assertEquals ( encoded , Geo3DUtil . encodeValue ( value ) ) ; } } } }
target:  step through some integers, ensuring they decode to their expected double values. double values start at -planetMax and increase by Geo3DUtil.DECODE for each integer. check edge cases within the double range and random doubles within the range too.