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Contracts on fractions

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This commit is contained in:
Claudio Maggioni 2022-11-30 18:24:52 +01:00
parent e2aedbbd2b
commit 5fbcc02c91
4 changed files with 81 additions and 28 deletions
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10
README.md
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@ -5,9 +5,13 @@ revision `770e72d2f78361b14f3fe27caea41e5977d3c638`
## List of semantically different functions with contracts
- Class `math.IEEE754rUtils` (converted from Utility/"static" class to allow use of contracts):
- `double min(double[])` and overloads
- `double max(double[])` and overloads
- Class `math.IEEE754rUtils`:
- `static double min(double[])` and overloads
- `static double max(double[])` and overloads
- Class `math.Fraction`
- `static Fraction getFraction(int, int)` and `static Fraction getFraction(int, int, int)`
- `static Fraction getReducedFraction(int, int)`
- (TODO PICK OTHER 3 FROM HERE)
- Class `CharRange`
- `boolean contains(CharRange)`
- Class `util.FluentBitSet`

7
src/main/java/ch/usi/inf/sdm/sdm04/math/Fraction.java
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@ -137,6 +137,8 @@ public final class Fraction extends Number implements Comparable<Fraction>, Frac
* @throws ArithmeticException if the denominator is {@code zero}
* or the denominator is {@code negative} and the numerator is {@code Integer#MIN_VALUE}
*/
@Pure
@Requires("get_fraction_pre")
public static Fraction getFraction(int numerator, int denominator) {
if (denominator == 0) {
throw new ArithmeticException("The denominator must not be zero");
@ -167,6 +169,9 @@ public final class Fraction extends Number implements Comparable<Fraction>, Frac
* @throws ArithmeticException if the resulting numerator exceeds
* {@code Integer.MAX_VALUE}
*/
@Pure
@Requires("get_fraction_whole_pre")
@Ensures("get_whole_fraction_post")
public static Fraction getFraction(final int whole, final int numerator, final int denominator) {
if (denominator == 0) {
throw new ArithmeticException("The denominator must not be zero");
@ -203,6 +208,8 @@ public final class Fraction extends Number implements Comparable<Fraction>, Frac
* @return a new fraction instance, with the numerator and denominator reduced
* @throws ArithmeticException if the denominator is {@code zero}
*/
@Requires("get_reduced_fraction_pre")
@Ensures("get_reduced_fraction_post")
public static Fraction getReducedFraction(int numerator, int denominator) {
if (denominator == 0) {
throw new ArithmeticException("The denominator must not be zero");

32
src/main/java/ch/usi/inf/sdm/sdm04/math/FractionContracts.java
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@ -21,5 +21,37 @@ package ch.usi.inf.sdm.sdm04.math;
import ch.usi.si.codelounge.jsicko.Contract;
@SuppressWarnings("unused") // used by jSicko
public interface FractionContracts extends Contract {
@Pure
static boolean get_fraction_pre(final int numerator, final int denominator) {
return denominator != 0 && (denominator > 0 ||
(numerator != Integer.MIN_VALUE && denominator != Integer.MIN_VALUE));
}
@Pure
static boolean get_reduced_fraction_pre(final int numerator, final int denominator) {
return denominator != 0 && (numerator != 0 || denominator != Integer.MIN_VALUE);
}
@Pure
static boolean get_fraction_whole_pre(final int whole, final int numerator, final int denominator) {
final long numeratorValue = whole * (long) denominator + (long) (whole > 0 ? 1 : -1) * numerator;
return numerator >= 0 && denominator > 0 &&
numeratorValue >= Integer.MIN_VALUE && numeratorValue <= Integer.MAX_VALUE;
}
@Pure
static boolean get_reduced_fraction_post(final Fraction returns, final int numerator, final int denominator) {
final Fraction f = Fraction.getFraction(numerator, denominator);
return returns.compareTo(f) == 0;
}
@Pure
static boolean get_whole_fraction_post(final Fraction returns, final int whole, final int numerator, final int denominator) {
final long numeratorValue = whole * (long) denominator + (long) (whole < 0 ? -1 : 1) * numerator;
final Fraction calc = Fraction.getFraction((int) numeratorValue, denominator);
return returns.compareTo(calc) == 0;
}
}

58
src/test/java/ch/usi/inf/sdm/sdm04/math/FractionTest.java
View file

@ -18,6 +18,7 @@
*/
package ch.usi.inf.sdm.sdm04.math;
import net.bytebuddy.implementation.bytecode.Throw;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;
@ -54,7 +55,8 @@ public class FractionTest {
assertEquals(Integer.MAX_VALUE, f.getNumerator());
assertEquals(1, f.getDenominator());
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(Integer.MIN_VALUE, 1).abs());
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getFraction(Integer.MIN_VALUE, 1).abs());
}
@Test
@ -420,13 +422,15 @@ public class FractionTest {
assertEquals(10, f.getDenominator());
// zero denominator
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(1, 0));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(2, 0));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(-3, 0));
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getFraction(1, 0));
assertThrows(Throwable.class, () -> Fraction.getFraction(2, 0));
assertThrows(Throwable.class, () -> Fraction.getFraction(-3, 0));
// very large: can't represent as unsimplified fraction, although
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(4, Integer.MIN_VALUE));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(1, Integer.MIN_VALUE));
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getFraction(4, Integer.MIN_VALUE));
assertThrows(Throwable.class, () -> Fraction.getFraction(1, Integer.MIN_VALUE));
}
@Test
@ -452,25 +456,28 @@ public class FractionTest {
assertEquals(2, f.getDenominator());
// negatives
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(1, -6, -10));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(1, -6, -10));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(1, -6, -10));
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getFraction(1, -6, -10));
assertThrows(Throwable.class, () -> Fraction.getFraction(1, -6, -10));
assertThrows(Throwable.class, () -> Fraction.getFraction(1, -6, -10));
// negative whole
f = Fraction.getFraction(-1, 6, 10);
assertEquals(-16, f.getNumerator());
assertEquals(10, f.getDenominator());
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(-1, -6, 10));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(-1, 6, -10));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(-1, -6, -10));
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getFraction(-1, -6, 10));
assertThrows(Throwable.class, () -> Fraction.getFraction(-1, 6, -10));
assertThrows(Throwable.class, () -> Fraction.getFraction(-1, -6, -10));
// zero denominator
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(0, 1, 0));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(1, 2, 0));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(-1, -3, 0));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(Integer.MAX_VALUE, 1, 2));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(-Integer.MAX_VALUE, 1, 2));
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getFraction(0, 1, 0));
assertThrows(Throwable.class, () -> Fraction.getFraction(1, 2, 0));
assertThrows(Throwable.class, () -> Fraction.getFraction(-1, -3, 0));
assertThrows(Throwable.class, () -> Fraction.getFraction(Integer.MAX_VALUE, 1, 2));
assertThrows(Throwable.class, () -> Fraction.getFraction(-Integer.MAX_VALUE, 1, 2));
// very large
f = Fraction.getFraction(-1, 0, Integer.MAX_VALUE);
@ -478,9 +485,10 @@ public class FractionTest {
assertEquals(Integer.MAX_VALUE, f.getDenominator());
// negative denominators not allowed in this constructor.
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(0, 4, Integer.MIN_VALUE));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(1, 1, Integer.MAX_VALUE));
assertThrows(ArithmeticException.class, () -> Fraction.getFraction(-1, 2, Integer.MAX_VALUE));
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getFraction(0, 4, Integer.MIN_VALUE));
assertThrows(Throwable.class, () -> Fraction.getFraction(1, 1, Integer.MAX_VALUE));
assertThrows(Throwable.class, () -> Fraction.getFraction(-1, 2, Integer.MAX_VALUE));
}
@Test
@ -914,9 +922,10 @@ public class FractionTest {
assertEquals(5, f.getDenominator());
// zero denominator
assertThrows(ArithmeticException.class, () -> Fraction.getReducedFraction(1, 0));
assertThrows(ArithmeticException.class, () -> Fraction.getReducedFraction(2, 0));
assertThrows(ArithmeticException.class, () -> Fraction.getReducedFraction(-3, 0));
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getReducedFraction(1, 0));
assertThrows(Throwable.class, () -> Fraction.getReducedFraction(2, 0));
assertThrows(Throwable.class, () -> Fraction.getReducedFraction(-3, 0));
// reduced
f = Fraction.getReducedFraction(0, 2);
@ -946,7 +955,8 @@ public class FractionTest {
assertEquals(-(Integer.MIN_VALUE / 2), f.getDenominator());
// Can't reduce, negation will throw
assertThrows(ArithmeticException.class, () -> Fraction.getReducedFraction(-7, Integer.MIN_VALUE));
// changed to allow jSicko violations
assertThrows(Throwable.class, () -> Fraction.getReducedFraction(-7, Integer.MIN_VALUE));
// LANG-662
f = Fraction.getReducedFraction(Integer.MIN_VALUE, 2);