net.jqwik.engine.properties.arbitraries.DefaultTraverseArbitrary Maven / Gradle / Ivy

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Jqwik Engine module
There is a newer version: 1.9.1
package net.jqwik.engine.properties.arbitraries;

import java.lang.reflect.*;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

import org.junit.platform.commons.support.*;

import net.jqwik.api.*;
import net.jqwik.api.arbitraries.*;
import net.jqwik.api.providers.*;
import net.jqwik.engine.support.types.*;

import static org.junit.platform.commons.support.ModifierSupport.*;

import static net.jqwik.engine.support.JqwikReflectionSupport.*;

public class DefaultTraverseArbitrary extends ArbitraryDecorator implements TraverseArbitrary {

	private final Class targetType;
	private final Traverser traverser;
	private final Map> arbitrariesCache;

	private boolean enableRecursion = false;

	public DefaultTraverseArbitrary(Class targetType, Traverser traverser) {
		this(targetType, traverser, new HashMap<>());
	}

	private DefaultTraverseArbitrary(Class targetType, Traverser traverser, Map> arbitrariesCache) {
		this.targetType = targetType;
		this.traverser = traverser;
		this.arbitrariesCache = arbitrariesCache;
	}

	@Override
	protected Arbitrary arbitrary() {
		TypeUsage targetTypeUsage = TypeUsage.forType(targetType);
		List> arbitraries = streamCreators(targetTypeUsage)
			.map(this::createArbitrary)
			.collect(Collectors.toList());

		if (arbitraries.isEmpty()) {
			String message = String.format(
				"No usable generator executables (constructors or factory methods) " +
					"have been provided for type [%s].",
				targetType
			);
			throw new JqwikException(message);
		}

		return Arbitraries.oneOf(arbitraries);
	}

	private Stream streamCreators(TypeUsage targetTypeUsage) {
		Set creators = traverser.findCreators(targetTypeUsage);
		return creators
			.stream()
			.filter(this::constructorIsConcrete)
			.filter(this::methodIsStatic)
			.filter(this::isNotRecursive)
			.map(this::checkFittingReturnType);
	}

	private boolean constructorIsConcrete(Executable executable) {
		if (executable instanceof Constructor) {
			Constructor ctor = (Constructor) executable;
			return !isAbstract(targetType);
		}
		return true;
	}

	private boolean methodIsStatic(Executable executable) {
		if (executable instanceof Method) {
			Method method = (Method) executable;
			return ModifierSupport.isStatic(method);
		}
		return true;
	}

	@Override
	public TraverseArbitrary enableRecursion() {
		DefaultTraverseArbitrary clone = typedClone();
		clone.enableRecursion = true;
		return clone;
	}

	private Executable checkFittingReturnType(Executable creator) {
		TypeUsage returnType = TypeUsage.forType(creator.getAnnotatedReturnType().getType());
		if (!returnType.canBeAssignedTo(TypeUsage.of(targetType))) {
			throw new JqwikException(String.format("%s should return type assignable to %s", creator, targetType));
		}
		return creator;
	}

	private boolean isNotRecursive(Executable creator) {
		// TODO: Check for real recursiveness not just direct recursive calls
		return Arrays.stream(creator.getParameterTypes()).noneMatch(parameterType -> parameterType.equals(targetType));
	}

	@Override
	public String toString() {
		return String.format("TraverseArbitrary<%s>(allowRecursion=%s)", targetType.getName(), enableRecursion);
	}

	private Arbitrary createArbitrary(
		Executable creator
	) {
		List> parameterArbitraries =
			getMethodParameters(creator, targetType)
				.stream()
				.map(methodParameter -> arbitraryFor(TypeUsageImpl.forParameter(methodParameter)))
				.collect(Collectors.toList());

		Function, T> combinator = paramList -> combinator(creator).apply(paramList.toArray());
		Arbitrary arbitrary = Combinators.combine(parameterArbitraries).as(combinator);
		return arbitrary.ignoreException(GenerationError.class);
	}

	private Arbitrary