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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.common.collect;
import org.elasticsearch.test.ESTestCase;
import java.util.*;
public class IteratorsTests extends ESTestCase {
public void testConcatentation() {
List<Integer> threeTwoOne = Arrays.asList(3, 2, 1);
List<Integer> fourFiveSix = Arrays.asList(4, 5, 6);
Iterator<Integer> concat = Iterators.concat(threeTwoOne.iterator(), fourFiveSix.iterator());
assertContainsInOrder(concat, 3, 2, 1, 4, 5, 6);
}
public void testNoConcatenation() {
Iterator<Integer> iterator = Iterators.<Integer>concat();
assertEmptyIterator(iterator);
}
public void testEmptyConcatenation() {
Iterator<Integer> iterator = Iterators.<Integer>concat(empty());
assertEmptyIterator(iterator);
}
public void testMultipleEmptyConcatenation() {
Iterator<Integer> iterator = Iterators.concat(empty(), empty());
assertEmptyIterator(iterator);
}
public void testSingleton() {
int value = randomInt();
assertSingleton(value, singletonIterator(value));
}
public void testEmptyBeforeSingleton() {
int value = randomInt();
assertSingleton(value, empty(), singletonIterator(value));
}
public void testEmptyAfterSingleton() {
int value = randomInt();
assertSingleton(value, singletonIterator(value), empty());
}
public void testRandomSingleton() {
int numberOfIterators = randomIntBetween(1, 1000);
int singletonIndex = randomIntBetween(0, numberOfIterators - 1);
int value = randomInt();
Iterator<Integer>[] iterators = new Iterator[numberOfIterators];
for (int i = 0; i < numberOfIterators; i++) {
iterators[i] = i != singletonIndex ? empty() : singletonIterator(value);
}
assertSingleton(value, iterators);
}
public void testRandomIterators() {
int numberOfIterators = randomIntBetween(1, 1000);
Iterator<Integer>[] iterators = new Iterator[numberOfIterators];
List<Integer> values = new ArrayList<>();
for (int i = 0; i < numberOfIterators; i++) {
int numberOfValues = randomIntBetween(0, 256);
List<Integer> theseValues = new ArrayList<>();
for (int j = 0; j < numberOfValues; j++) {
int value = randomInt();
values.add(value);
theseValues.add(value);
}
iterators[i] = theseValues.iterator();
}
assertContainsInOrder(Iterators.concat(iterators), values.toArray(new Integer[values.size()]));
}
public void testTwoEntries() {
int first = randomInt();
int second = randomInt();
Iterator<Integer> concat = Iterators.concat(singletonIterator(first), empty(), empty(), singletonIterator(second));
assertContainsInOrder(concat, first, second);
}
public void testNull() {
try {
Iterators.concat((Iterator<?>)null);
fail("expected " + NullPointerException.class.getSimpleName());
} catch (NullPointerException e) {
}
}
public void testNullIterator() {
try {
Iterators.concat(singletonIterator(1), empty(), null, empty(), singletonIterator(2));
fail("expected " + NullPointerException.class.getSimpleName());
} catch (NullPointerException e) {
}
}
private <T> Iterator<T> singletonIterator(T value) {
return Collections.singleton(value).iterator();
}
private <T> void assertSingleton(T value, Iterator<T>... iterators) {
Iterator<T> concat = Iterators.concat(iterators);
assertContainsInOrder(concat, value);
}
private <T> Iterator<T> empty() {
return new Iterator<T>() {
@Override
public boolean hasNext() {
return false;
}
@Override
public T next() {
throw new NoSuchElementException();
}
};
}
private <T> void assertContainsInOrder(Iterator<T> iterator, T... values) {
for (T value : values) {
assertTrue(iterator.hasNext());
assertEquals(value, iterator.next());
}
assertNoSuchElementException(iterator);
}
private <T> void assertEmptyIterator(Iterator<T> iterator) {
assertFalse(iterator.hasNext());
assertNoSuchElementException(iterator);
}
private <T> void assertNoSuchElementException(Iterator<T> iterator) {
try {
iterator.next();
fail("expected " + NoSuchElementException.class.getSimpleName());
} catch (NoSuchElementException e) {
}
}
}
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