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Guava testlib is a set of java classes used for more convenient
unit testing - particularly to assist the tests for Guava itself.
/*
* Copyright (C) 2008 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.collect.testing.features;
import com.google.common.collect.testing.Helpers;
import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
/**
* Utilities for collecting and validating tester requirements from annotations.
*
* @author George van den Driessche
*/
public class FeatureUtil {
/**
* A cache of annotated objects (typically a Class or Method) to its
* set of annotations.
*/
private static Map annotationCache =
new HashMap();
private static final Map, TesterRequirements>
classTesterRequirementsCache =
new HashMap, TesterRequirements>();
/**
* Given a set of features, add to it all the features directly or indirectly
* implied by any of them, and return it.
* @param features the set of features to expand
* @return the same set of features, expanded with all implied features
*/
public static Set> addImpliedFeatures(Set> features) {
// The base case of the recursion is an empty set of features, which will
// occur when the previous set contained only simple features.
if (!features.isEmpty()) {
features.addAll(impliedFeatures(features));
}
return features;
}
/**
* Given a set of features, return a new set of all features directly or
* indirectly implied by any of them.
* @param features the set of features whose implications to find
* @return the implied set of features
*/
public static Set> impliedFeatures(Set> features) {
Set> implied = new LinkedHashSet>();
for (Feature feature : features) {
implied.addAll(feature.getImpliedFeatures());
}
addImpliedFeatures(implied);
return implied;
}
/**
* Get the full set of requirements for a tester class.
* @param testerClass a tester class
* @return all the constraints implicitly or explicitly required by the class
* or any of its superclasses.
* @throws ConflictingRequirementsException if the requirements are mutually
* inconsistent.
*/
public static TesterRequirements getTesterRequirements(Class testerClass)
throws ConflictingRequirementsException {
synchronized (classTesterRequirementsCache) {
TesterRequirements requirements =
classTesterRequirementsCache.get(testerClass);
if (requirements == null) {
requirements = buildTesterRequirements(testerClass);
classTesterRequirementsCache.put(testerClass, requirements);
}
return requirements;
}
}
/**
* Get the full set of requirements for a tester class.
* @param testerMethod a test method of a tester class
* @return all the constraints implicitly or explicitly required by the
* method, its declaring class, or any of its superclasses.
* @throws ConflictingRequirementsException if the requirements are
* mutually inconsistent.
*/
public static TesterRequirements getTesterRequirements(Method testerMethod)
throws ConflictingRequirementsException {
return buildTesterRequirements(testerMethod);
}
/**
* Construct the full set of requirements for a tester class.
* @param testerClass a tester class
* @return all the constraints implicitly or explicitly required by the class
* or any of its superclasses.
* @throws ConflictingRequirementsException if the requirements are mutually
* inconsistent.
*/
static TesterRequirements buildTesterRequirements(Class testerClass)
throws ConflictingRequirementsException {
final TesterRequirements declaredRequirements =
buildDeclaredTesterRequirements(testerClass);
Class baseClass = testerClass.getSuperclass();
if (baseClass == null) {
return declaredRequirements;
} else {
final TesterRequirements clonedBaseRequirements =
new TesterRequirements(getTesterRequirements(baseClass));
return incorporateRequirements(
clonedBaseRequirements, declaredRequirements, testerClass);
}
}
/**
* Construct the full set of requirements for a tester method.
* @param testerMethod a test method of a tester class
* @return all the constraints implicitly or explicitly required by the
* method, its declaring class, or any of its superclasses.
* @throws ConflictingRequirementsException if the requirements are mutually
* inconsistent.
*/
static TesterRequirements buildTesterRequirements(Method testerMethod)
throws ConflictingRequirementsException {
TesterRequirements clonedClassRequirements = new TesterRequirements(
getTesterRequirements(testerMethod.getDeclaringClass()));
TesterRequirements declaredRequirements =
buildDeclaredTesterRequirements(testerMethod);
return incorporateRequirements(
clonedClassRequirements, declaredRequirements, testerMethod);
}
/**
* Construct the set of requirements specified by annotations
* directly on a tester class or method.
* @param classOrMethod a tester class or a test method thereof
* @return all the constraints implicitly or explicitly required by
* annotations on the class or method.
* @throws ConflictingRequirementsException if the requirements are mutually
* inconsistent.
*/
public static TesterRequirements buildDeclaredTesterRequirements(
AnnotatedElement classOrMethod)
throws ConflictingRequirementsException {
TesterRequirements requirements = new TesterRequirements();
Iterable testerAnnotations =
getTesterAnnotations(classOrMethod);
for (Annotation testerAnnotation : testerAnnotations) {
TesterRequirements moreRequirements =
buildTesterRequirements(testerAnnotation);
incorporateRequirements(
requirements, moreRequirements, testerAnnotation);
}
return requirements;
}
/**
* Find all the tester annotations declared on a tester class or method.
* @param classOrMethod a class or method whose tester annotations to find
* @return an iterable sequence of tester annotations on the class
*/
public static Iterable getTesterAnnotations(
AnnotatedElement classOrMethod) {
List result = new ArrayList();
Annotation[] annotations;
synchronized (annotationCache) {
annotations = annotationCache.get(classOrMethod);
if (annotations == null) {
annotations = classOrMethod.getDeclaredAnnotations();
annotationCache.put(classOrMethod, annotations);
}
}
for (Annotation a : annotations) {
Class annotationClass = a.annotationType();
if (annotationClass.isAnnotationPresent(TesterAnnotation.class)) {
result.add(a);
}
}
return result;
}
/**
* Find all the constraints explicitly or implicitly specified by a single
* tester annotation.
* @param testerAnnotation a tester annotation
* @return the requirements specified by the annotation
* @throws ConflictingRequirementsException if the requirements are mutually
* inconsistent.
*/
private static TesterRequirements buildTesterRequirements(
Annotation testerAnnotation)
throws ConflictingRequirementsException {
Class annotationClass = testerAnnotation.annotationType();
final Feature[] presentFeatures;
final Feature[] absentFeatures;
try {
presentFeatures = (Feature[]) annotationClass.getMethod("value")
.invoke(testerAnnotation);
absentFeatures = (Feature[]) annotationClass.getMethod("absent")
.invoke(testerAnnotation);
} catch (Exception e) {
throw new IllegalArgumentException(
"Error extracting features from tester annotation.", e);
}
Set> allPresentFeatures =
addImpliedFeatures(Helpers.>copyToSet(presentFeatures));
Set> allAbsentFeatures =
addImpliedFeatures(Helpers.>copyToSet(absentFeatures));
Set> conflictingFeatures =
intersection(allPresentFeatures, allAbsentFeatures);
if (!conflictingFeatures.isEmpty()) {
throw new ConflictingRequirementsException("Annotation explicitly or "
+ "implicitly requires one or more features to be both present "
+ "and absent.",
conflictingFeatures, testerAnnotation);
}
return new TesterRequirements(allPresentFeatures, allAbsentFeatures);
}
/**
* Incorporate additional requirements into an existing requirements object.
* @param requirements the existing requirements object
* @param moreRequirements more requirements to incorporate
* @param source the source of the additional requirements
* (used only for error reporting)
* @return the existing requirements object, modified to include the
* additional requirements
* @throws ConflictingRequirementsException if the additional requirements
* are inconsistent with the existing requirements
*/
private static TesterRequirements incorporateRequirements(
TesterRequirements requirements, TesterRequirements moreRequirements,
Object source) throws ConflictingRequirementsException {
Set> presentFeatures = requirements.getPresentFeatures();
Set> absentFeatures = requirements.getAbsentFeatures();
Set> morePresentFeatures = moreRequirements.getPresentFeatures();
Set> moreAbsentFeatures = moreRequirements.getAbsentFeatures();
checkConflict(
"absent", absentFeatures,
"present", morePresentFeatures, source);
checkConflict(
"present", presentFeatures,
"absent", moreAbsentFeatures, source);
presentFeatures.addAll(morePresentFeatures);
absentFeatures.addAll(moreAbsentFeatures);
return requirements;
}
// Used by incorporateRequirements() only
private static void checkConflict(
String earlierRequirement, Set> earlierFeatures,
String newRequirement, Set> newFeatures,
Object source) throws ConflictingRequirementsException {
Set> conflictingFeatures;
conflictingFeatures = intersection(newFeatures, earlierFeatures);
if (!conflictingFeatures.isEmpty()) {
throw new ConflictingRequirementsException(String.format(Locale.ROOT,
"Annotation requires to be %s features that earlier "
+ "annotations required to be %s.",
newRequirement, earlierRequirement),
conflictingFeatures, source);
}
}
/**
* Construct a new {@link java.util.Set} that is the intersection
* of the given sets.
*/
// Calls generic varargs method.
@SuppressWarnings("unchecked")
public static Set intersection(
Set set1, Set set2) {
return intersection(new Set[] {set1, set2});
}
/**
* Construct a new {@link java.util.Set} that is the intersection
* of all the given sets.
* @param sets the sets to intersect
* @return the intersection of the sets
* @throws java.lang.IllegalArgumentException if there are no sets to
* intersect
*/
public static Set intersection(Set ... sets) {
if (sets.length == 0) {
throw new IllegalArgumentException(
"Can't intersect no sets; would have to return the universe.");
}
Set results = Helpers.copyToSet(sets[0]);
for (int i = 1; i < sets.length; i++) {
Set set = sets[i];
results.retainAll(set);
}
return results;
}
}
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