javaslang.test.Checkable Maven / Gradle / Ivy
/* / \____ _ ______ _____ / \____ ____ _____
* / \__ \/ \ / \__ \ / __// \__ \ / \/ __ \ Javaslang
* _/ // _\ \ \/ / _\ \\_ \/ // _\ \ /\ \__/ / Copyright 2014-2015 Daniel Dietrich
* /___/ \_____/\____/\_____/____/\___\_____/_/ \_/____/ Licensed under the Apache License, Version 2.0
*/
package javaslang.test;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.Supplier;
/**
* Interface for checkable properties, allowing composition via {@linkplain #and(Checkable)} and {@linkplain #or(Checkable)}.
*
* @author Daniel Dietrich
* @since 1.2.0
*/
@FunctionalInterface
public interface Checkable {
/**
* A thread-safe, equally distributed random number generator.
*/
Supplier RNG = ThreadLocalRandom::current;
/**
* Default size hint for generators: 100
*/
int DEFAULT_SIZE = 100;
/**
* Default tries to check a property: 1000
*/
int DEFAULT_TRIES = 1000;
/**
* Checks this property.
*
* @param randomNumberGenerator An implementation of {@link java.util.Random}.
* @param size A (not necessarily positive) size hint.
* @param tries A non-negative number of tries to falsify the given property.
* @return A {@linkplain CheckResult}
*/
CheckResult check(Random randomNumberGenerator, int size, int tries);
/**
* Checks this property using the default random number generator {@link #RNG}.
*
* @param size A (not necessarily positive) size hint.
* @param tries A non-negative number of tries to falsify the given property.
* @return A {@linkplain CheckResult}
*/
default CheckResult check(int size, int tries) {
if (tries < 0) {
throw new IllegalArgumentException("tries < 0");
}
return check(RNG.get(), size, tries);
}
/**
* Checks this property using the default random number generator {@link #RNG} by calling {@link #check(int, int)},
* where size is {@link #DEFAULT_SIZE} and tries is {@link #DEFAULT_TRIES}.
*
* @return A {@linkplain CheckResult}
*/
default CheckResult check() {
return check(RNG.get(), DEFAULT_SIZE, DEFAULT_TRIES);
}
/**
* Returns a new Checkable which is satisfied if this Checkable and the given checkable are satisfied.
*
* First this Checkable is checked.
*
* @param checkable A Checkable
* @return A new Checkable
*/
default Checkable and(Checkable checkable) {
return (rng, size, tries) -> {
final CheckResult result = check(rng, size, tries);
if (result.isSatisfied()) {
return checkable.check(rng, size, tries);
} else {
return result;
}
};
}
/**
* Returns a new Checkable which is satisfied if this Checkable or the given checkable are satisfied.
*
* First this Checkable is checked.
*
* @param checkable A Checkable
* @return A new Checkable
*/
default Checkable or(Checkable checkable) {
return (rng, size, tries) -> {
final CheckResult result = check(rng, size, tries);
if (result.isSatisfied()) {
return result;
} else {
return checkable.check(rng, size, tries);
}
};
}
}