Class MathTesting

guava-tests/test/com/google/common/math/MathTesting.java:44–255

Exhaustive input sets for every integral type. @author Louis Wasserman

 * @author Louis Wasserman
 */
@GwtCompatible
@NullUnmarked
public final class MathTesting {
  static final ImmutableSet<RoundingMode> ALL_ROUNDING_MODES =
      ImmutableSet.copyOf(RoundingMode.values());

  static final ImmutableList<RoundingMode> ALL_SAFE_ROUNDING_MODES =
      ImmutableList.of(DOWN, UP, FLOOR, CEILING, HALF_EVEN, HALF_UP, HALF_DOWN);

  // Exponents to test for the pow() function.
  static final ImmutableList<Integer> EXPONENTS =
      ImmutableList.of(0, 1, 2, 3, 4, 7, 10, 15, 20, 25, 40, 70);

  /*
   * This list contains values that attempt to provoke overflow in integer operations. It contains
   * positive values on or near 2^N for N near multiples of 8 (near byte boundaries).
   */
  static final ImmutableSet<Integer> POSITIVE_INTEGER_CANDIDATES;

  static final Iterable<Integer> NEGATIVE_INTEGER_CANDIDATES;

  static final Iterable<Integer> NONZERO_INTEGER_CANDIDATES;

  static final Iterable<Integer> ALL_INTEGER_CANDIDATES;

  static {
    ImmutableSet.Builder<Integer> intValues = ImmutableSet.builder();
    // Add boundary values manually to avoid over/under flow (this covers 2^N for 0 and 31).
    intValues.add(Integer.MAX_VALUE - 1, Integer.MAX_VALUE);
    // Add values up to 40. This covers cases like "square of a prime" and such.
    for (int i = 1; i <= 40; i++) {
      intValues.add(i);
    }
    // Now add values near 2^N for lots of values of N.
    for (int exponent : asList(2, 3, 4, 9, 15, 16, 17, 24, 25, 30)) {
      int x = 1 << exponent;
      intValues.add(x, x + 1, x - 1);
    }
    intValues.add(9999).add(10000).add(10001).add(1000000); // near powers of 10
    intValues.add(5792).add(5793); // sqrt(2^25) rounded up and down
    POSITIVE_INTEGER_CANDIDATES = intValues.build();
    NEGATIVE_INTEGER_CANDIDATES =
        ImmutableList.copyOf(
            Iterables.concat(
                Iterables.transform(POSITIVE_INTEGER_CANDIDATES, x -> -x),
                ImmutableList.of(Integer.MIN_VALUE)));
    NONZERO_INTEGER_CANDIDATES =
        ImmutableList.copyOf(
            Iterables.concat(POSITIVE_INTEGER_CANDIDATES, NEGATIVE_INTEGER_CANDIDATES));
    ALL_INTEGER_CANDIDATES = Iterables.concat(NONZERO_INTEGER_CANDIDATES, ImmutableList.of(0));
  }

  /*
   * This list contains values that attempt to provoke overflow in long operations. It contains
   * positive values on or near 2^N for N near multiples of 8 (near byte boundaries). This list is
   * a superset of POSITIVE_INTEGER_CANDIDATES.
   */
  static final ImmutableSet<Long> POSITIVE_LONG_CANDIDATES;