ComparatorChainTest.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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
*
* https://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.apache.commons.collections4.comparators;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.io.Serializable;
import java.util.Arrays;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;
import org.junit.jupiter.api.Test;
/**
* Tests for ComparatorChain.
*/
class ComparatorChainTest extends AbstractComparatorTest<ComparatorChainTest.PseudoRow> {
public static class ColumnComparator implements Comparator<PseudoRow>, Serializable {
private static final long serialVersionUID = -2284880866328872105L;
protected int colIndex;
ColumnComparator(final int colIndex) {
this.colIndex = colIndex;
}
@Override
public int compare(final PseudoRow o1, final PseudoRow o2) {
return Integer.compare(o1.getColumn(colIndex), o2.getColumn(colIndex));
}
@Override
public boolean equals(final Object that) {
return that instanceof ColumnComparator && colIndex == ((ColumnComparator) that).colIndex;
}
@Override
public int hashCode() {
return colIndex;
}
}
public static class PseudoRow implements Serializable {
/**
* Generated serial version ID.
*/
private static final long serialVersionUID = 8085570439751032499L;
public int[] cols = new int[3];
PseudoRow(final int col1, final int col2, final int col3) {
cols[0] = col1;
cols[1] = col2;
cols[2] = col3;
}
@Override
public boolean equals(final Object o) {
if (!(o instanceof PseudoRow)) {
return false;
}
final PseudoRow row = (PseudoRow) o;
return getColumn(0) == row.getColumn(0) && getColumn(1) == row.getColumn(1) && getColumn(2) == row.getColumn(2);
}
public int getColumn(final int colIndex) {
return cols[colIndex];
}
@Override
public int hashCode() {
return Arrays.hashCode(cols);
}
@Override
public String toString() {
return "[" + cols[0] + "," + cols[1] + "," + cols[2] + "]";
}
}
// void testCreate() throws Exception {
// writeExternalFormToDisk((java.io.Serializable) makeObject(), "src/test/resources/data/test/ComparatorChain.version4.obj");
// }
@Override
public List<PseudoRow> getComparableObjectsOrdered() {
// this is the correct order assuming a
// "0th forward, 1st reverse, 2nd forward" sort
return new LinkedList<>(Arrays.asList(new PseudoRow(1, 2, 3), new PseudoRow(2, 3, 5),
new PseudoRow(2, 2, 4), new PseudoRow(2, 2, 8), new PseudoRow(3, 1, 0),
new PseudoRow(4, 4, 4), new PseudoRow(4, 4, 7)));
}
@Override
public String getCompatibilityVersion() {
return "4";
}
@Override
public Comparator<PseudoRow> makeObject() {
final ComparatorChain<PseudoRow> chain = new ComparatorChain<>(new ColumnComparator(0));
chain.addComparator(new ColumnComparator(1), true); // reverse the second column
chain.addComparator(new ColumnComparator(2), false);
return chain;
}
@Test
void testBadListComparatorChain() {
final List<Comparator<Integer>> list = new LinkedList<>();
final ComparatorChain<Integer> chain = new ComparatorChain<>(list);
final Integer i1 = 4;
final Integer i2 = 6;
assertThrows(UnsupportedOperationException.class, () -> chain.compare(i1, i2));
}
@Test
void testBadNoopComparatorChain() {
final ComparatorChain<Integer> chain = new ComparatorChain<>();
final Integer i1 = 4;
final Integer i2 = 6;
assertThrows(UnsupportedOperationException.class, () -> chain.compare(i1, i2), "An exception should be thrown when a chain contains zero comparators.");
}
@Test
void testComparatorChainOnMinValuedComparator() {
// -1 * Integer.MIN_VALUE is less than 0,
// test that ComparatorChain handles this edge case correctly
final ComparatorChain<Integer> chain = new ComparatorChain<>();
chain.addComparator((a, b) -> {
final int result = a.compareTo(b);
if (result < 0) {
return Integer.MIN_VALUE;
}
if (result > 0) {
return Integer.MAX_VALUE;
}
return 0;
}, true);
assertTrue(chain.compare(4, 5) > 0);
assertTrue(chain.compare(5, 4) < 0);
assertEquals(0, chain.compare(4, 4));
}
@Test
void testListComparatorChain() {
final List<Comparator<Integer>> list = new LinkedList<>();
list.add(new ComparableComparator<>());
final ComparatorChain<Integer> chain = new ComparatorChain<>(list);
final Integer i1 = 4;
final Integer i2 = 6;
final int correctValue = i1.compareTo(i2);
assertEquals(chain.compare(i1, i2), correctValue, "Comparison returns the right order");
}
@Test
void testNoopComparatorChain() {
final ComparatorChain<Integer> chain = new ComparatorChain<>();
final Integer i1 = 4;
final Integer i2 = 6;
chain.addComparator(new ComparableComparator<>());
final int correctValue = i1.compareTo(i2);
assertEquals(chain.compare(i1, i2), correctValue, "Comparison returns the right order");
}
}