/*
* Copyright (C) 2007 Google Inc.
*
* 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;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.collect.Ordering.IncomparableValueException;
import com.google.common.collect.testing.Helpers;
import static com.google.common.testing.junit3.JUnitAsserts.assertContentsInOrder;
import com.google.common.testutils.EqualsTester;
import com.google.common.testutils.NullPointerTester;
import static com.google.common.testutils.SerializableTester.reserialize;
import static com.google.common.testutils.SerializableTester.reserializeAndAssert;
import junit.framework.TestCase;
import java.util.Arrays;
import static java.util.Arrays.asList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Random;
import javax.annotation.Nullable;
/**
* Unit tests for {@code Ordering}.
*
* @author Jesse Wilson
*/
public class OrderingTest extends TestCase {
private final Ordering<Number> numberOrdering = new NumberOrdering();
public void testNatural() {
Ordering<Integer> comparator = Ordering.natural();
Helpers.testComparator(comparator,
Integer.MIN_VALUE, -1, 0, 1, Integer.MAX_VALUE);
try {
comparator.compare(1, null);
fail();
} catch (NullPointerException expected) {}
try {
comparator.compare(null, 2);
fail();
} catch (NullPointerException expected) {}
try {
comparator.compare(null, null);
fail();
} catch (NullPointerException expected) {}
assertSame(comparator, reserialize(comparator));
assertEquals("Ordering.natural()", comparator.toString());
}
public void testFrom() {
Ordering<String> caseInsensitiveOrdering
= Ordering.from(String.CASE_INSENSITIVE_ORDER);
assertEquals(0, caseInsensitiveOrdering.compare("A", "a"));
assertTrue(caseInsensitiveOrdering.compare("a", "B") < 0);
assertTrue(caseInsensitiveOrdering.compare("B", "a") > 0);
@SuppressWarnings("deprecation") // test of deprecated method
Ordering<String> orderingFromOrdering =
Ordering.from(Ordering.<String>natural());
new EqualsTester(caseInsensitiveOrdering)
.addEqualObject(Ordering.from(String.CASE_INSENSITIVE_ORDER))
.addNotEqualObject(orderingFromOrdering)
.addNotEqualObject(Ordering.natural())
.testEquals();
}
public void testExplicit_none() {
Comparator<Integer> c
= Ordering.explicit(Collections.<Integer>emptyList());
try {
c.compare(0, 0);
fail();
} catch (IncomparableValueException expected) {
assertEquals(0, expected.value);
}
reserializeAndAssert(c);
}
public void testExplicit_one() {
Comparator<Integer> c = Ordering.explicit(0);
assertEquals(0, c.compare(0, 0));
try {
c.compare(0, 1);
fail();
} catch (IncomparableValueException expected) {
assertEquals(1, expected.value);
}
reserializeAndAssert(c);
assertEquals("Ordering.explicit([0])", c.toString());
}
public void testExplicit_two() {
Comparator<Integer> c = Ordering.explicit(42, 5);
assertEquals(0, c.compare(5, 5));
assertTrue(c.compare(5, 42) > 0);
assertTrue(c.compare(42, 5) < 0);
try {
c.compare(5, 666);
fail();
} catch (IncomparableValueException expected) {
assertEquals(666, expected.value);
}
new EqualsTester(c)
.addEqualObject(Ordering.explicit(42, 5))
.addNotEqualObject(Ordering.explicit(5, 42))
.addNotEqualObject(Ordering.explicit(42))
.testEquals();
reserializeAndAssert(c);
}
public void testExplicit_sortingExample() {
Comparator<Integer> c
= Ordering.explicit(2, 8, 6, 1, 7, 5, 3, 4, 0, 9);
List<Integer> list = Arrays.asList(0, 3, 5, 6, 7, 8, 9);
Collections.sort(list, c);
assertContentsInOrder(list, 8, 6, 7, 5, 3, 0, 9);
reserializeAndAssert(c);
}
public void testExplicit_withDuplicates() {
try {
Ordering.explicit(1, 2, 3, 4, 2);
fail();
} catch (IllegalArgumentException expected) {
}
}
public void testUsingToString() {
Ordering<Object> ordering = Ordering.usingToString();
Helpers.testComparator(ordering, 1, 12, 124, 2);
assertEquals("Ordering.usingToString()", ordering.toString());
assertSame(ordering, reserialize(ordering));
}
// use an enum to get easy serializability
private enum CharAtFunction implements Function<String, Character> {
AT0(0),
AT1(1),
AT2(2),
AT3(3),
AT4(4),
AT5(5),
;
final int index;
CharAtFunction(int index) {
this.index = index;
}
public Character apply(String string) {
return string.charAt(index);
}
}
private static Ordering<String> byCharAt(int index) {
return Ordering.natural().onResultOf(CharAtFunction.values()[index]);
}
public void testCompound_static() {
Comparator<String> comparator = Ordering.compound(
Iterables.unmodifiableIterable(ImmutableList.of(
byCharAt(0), byCharAt(1), byCharAt(2),
byCharAt(3), byCharAt(4), byCharAt(5))));
Helpers.testComparator(comparator, ImmutableList.of(
"applesauce",
"apricot",
"artichoke",
"banality",
"banana",
"banquet",
"tangelo",
"tangerine"));
reserializeAndAssert(comparator);
}
public void testCompound_instance() {
Comparator<String> comparator = byCharAt(1).compound(byCharAt(0));
Helpers.testComparator(comparator, ImmutableList.of(
"red",
"yellow",
"violet",
"blue",
"indigo",
"green",
"orange"));
}
public void testCompound_instance_generics() {
Ordering<Object> objects = Ordering.explicit((Object) 1);
Ordering<Number> numbers = Ordering.explicit((Number) 1);
Ordering<Integer> integers = Ordering.explicit(1);
// Like by like equals like
Ordering<Number> a = numbers.compound(numbers);
// The compound takes the more specific type of the two, regardless of order
Ordering<Number> b = numbers.compound(objects);
Ordering<Number> c = objects.compound(numbers);
Ordering<Integer> d = numbers.compound(integers);
Ordering<Integer> e = integers.compound(numbers);
// This works with three levels too (IDEA falsely reports errors as noted
// below. Both javac and eclipse handle these cases correctly.)
Ordering<Number> f = numbers.compound(objects).compound(objects); //bad IDEA
Ordering<Number> g = objects.compound(numbers).compound(objects);
Ordering<Number> h = objects.compound(objects).compound(numbers);
Ordering<Number> i = numbers.compound(objects.compound(objects));
Ordering<Number> j = objects.compound(numbers.compound(objects)); //bad IDEA
Ordering<Number> k = objects.compound(objects.compound(numbers));
// You can also arbitrarily assign a more restricted type - not an intended
// feature, exactly, but unavoidable (I think) and harmless
Ordering<Integer> l = objects.compound(numbers);
// This correctly doesn't work:
// Ordering<Object> m = numbers.compound(objects);
// Sadly, the following works in javac 1.6, but at least it fails for
// eclipse, and is *correctly* highlighted red in IDEA.
// Ordering<Object> n = objects.compound(numbers);
}
public void testReverse() {
Ordering<Number> reverseOrder = numberOrdering.reverse();
Helpers.testComparator(reverseOrder,
Integer.MAX_VALUE, 1, 0, -1, Integer.MIN_VALUE);
new EqualsTester(reverseOrder)
.addEqualObject(numberOrdering.reverse())
.addNotEqualObject(Ordering.natural().reverse())
.addNotEqualObject(Collections.reverseOrder())
.testEquals();
}
public void testReverseOfReverseSameAsForward() {
// Not guaranteed by spec, but it works, and saves us from testing
// exhaustively
assertSame(numberOrdering, numberOrdering.reverse().reverse());
}
private enum StringLengthFunction implements Function<String, Integer> {
StringLength;
public Integer apply(String string) {
return string.length();
}
}
private static final Ordering<Integer> DECREASING_INTEGER
= Ordering.natural().reverse();
public void testOnResultOf_natural() {
Comparator<String> comparator
= Ordering.natural().onResultOf(StringLengthFunction.StringLength);
assertTrue(comparator.compare("to", "be") == 0);
assertTrue(comparator.compare("or", "not") < 0);
assertTrue(comparator.compare("that", "to") > 0);
new EqualsTester(comparator)
.addEqualObject(
Ordering.natural().onResultOf(StringLengthFunction.StringLength))
.addNotEqualObject(DECREASING_INTEGER)
.testEquals();
reserializeAndAssert(comparator);
assertEquals("Ordering.natural().onResultOf(StringLength)",
comparator.toString());
}
public void testOnResultOf_chained() {
Comparator<String> comparator = DECREASING_INTEGER.onResultOf(
StringLengthFunction.StringLength);
assertTrue(comparator.compare("to", "be") == 0);
assertTrue(comparator.compare("not", "or") < 0);
assertTrue(comparator.compare("to", "that") > 0);
new EqualsTester(comparator)
.addEqualObject(
DECREASING_INTEGER.onResultOf(StringLengthFunction.StringLength))
.addNotEqualObject(
DECREASING_INTEGER.onResultOf(Functions.constant(1)))
.addNotEqualObject(Ordering.natural())
.testEquals();
reserializeAndAssert(comparator);
assertEquals("Ordering.natural().reverse().onResultOf(StringLength)",
comparator.toString());
}
public void testNullsFirst() {
Ordering<Integer> ordering = Ordering.natural().nullsFirst();
Helpers.testComparator(ordering, null, Integer.MIN_VALUE, 0, 1);
}
public void testNullsLast() {
Ordering<Integer> ordering = Ordering.natural().nullsLast();
Helpers.testComparator(ordering, 0, 1, Integer.MAX_VALUE, null);
}
public void testBinarySearch() {
List<Integer> ints = Lists.newArrayList(0, 2, 3, 5, 7, 9);
assertEquals(4, numberOrdering.binarySearch(ints, 7));
}
public void testSortedCopy() {
List<Integer> unsortedInts = Lists.newArrayList(5, 3, 0, 9);
List<Integer> sortedInts = numberOrdering.sortedCopy(unsortedInts);
assertEquals(Lists.newArrayList(0, 3, 5, 9), sortedInts);
assertEquals(Lists.newArrayList(5, 3, 0, 9), unsortedInts);
}
public void testIsOrdered() {
assertFalse(numberOrdering.isOrdered(asList(5, 3, 0, 9)));
assertFalse(numberOrdering.isOrdered(asList(0, 5, 3, 9)));
assertTrue(numberOrdering.isOrdered(asList(0, 3, 5, 9)));
assertTrue(numberOrdering.isOrdered(asList(0, 0, 3, 3)));
assertTrue(numberOrdering.isOrdered(asList(0, 3)));
assertTrue(numberOrdering.isOrdered(Collections.singleton(1)));
assertTrue(numberOrdering.isOrdered(Collections.<Integer>emptyList()));
}
public void testIsStrictlyOrdered() {
assertFalse(numberOrdering.isStrictlyOrdered(asList(5, 3, 0, 9)));
assertFalse(numberOrdering.isStrictlyOrdered(asList(0, 5, 3, 9)));
assertTrue(numberOrdering.isStrictlyOrdered(asList(0, 3, 5, 9)));
assertFalse(numberOrdering.isStrictlyOrdered(asList(0, 0, 3, 3)));
assertTrue(numberOrdering.isStrictlyOrdered(asList(0, 3)));
assertTrue(numberOrdering.isStrictlyOrdered(Collections.singleton(1)));
assertTrue(numberOrdering.isStrictlyOrdered(
Collections.<Integer>emptyList()));
}
public void testIterableMinAndMax() {
List<Integer> ints = Lists.newArrayList(5, 3, 0, 9);
assertEquals(9, (int) numberOrdering.max(ints));
assertEquals(0, (int) numberOrdering.min(ints));
// when the values are the same, the first argument should be returned
Integer a = new Integer(4);
Integer b = new Integer(4);
ints = Lists.newArrayList(a, b, b);
assertSame(a, numberOrdering.max(ints));
assertSame(a, numberOrdering.min(ints));
}
public void testVarargsMinAndMax() {
// try the min and max values in all positions, since some values are proper
// parameters and others are from the varargs array
assertEquals(9, (int) numberOrdering.max(9, 3, 0, 5, 8));
assertEquals(9, (int) numberOrdering.max(5, 9, 0, 3, 8));
assertEquals(9, (int) numberOrdering.max(5, 3, 9, 0, 8));
assertEquals(9, (int) numberOrdering.max(5, 3, 0, 9, 8));
assertEquals(9, (int) numberOrdering.max(5, 3, 0, 8, 9));
assertEquals(0, (int) numberOrdering.min(0, 3, 5, 9, 8));
assertEquals(0, (int) numberOrdering.min(5, 0, 3, 9, 8));
assertEquals(0, (int) numberOrdering.min(5, 3, 0, 9, 8));
assertEquals(0, (int) numberOrdering.min(5, 3, 9, 0, 8));
assertEquals(0, (int) numberOrdering.min(5, 3, 0, 9, 0));
// when the values are the same, the first argument should be returned
Integer a = new Integer(4);
Integer b = new Integer(4);
assertSame(a, numberOrdering.max(a, b, b));
assertSame(a, numberOrdering.min(a, b, b));
}
public void testParameterMinAndMax() {
assertEquals(5, (int) numberOrdering.max(3, 5));
assertEquals(5, (int) numberOrdering.max(5, 3));
assertEquals(3, (int) numberOrdering.min(3, 5));
assertEquals(3, (int) numberOrdering.min(5, 3));
// when the values are the same, the first argument should be returned
Integer a = new Integer(4);
Integer b = new Integer(4);
assertSame(a, numberOrdering.max(a, b));
assertSame(a, numberOrdering.min(a, b));
}
private static class NumberOrdering extends Ordering<Number> {
public int compare(Number a, Number b) {
return ((Double) a.doubleValue()).compareTo(b.doubleValue());
}
@Override public int hashCode() {
return NumberOrdering.class.hashCode();
}
@Override public boolean equals(Object other) {
return other instanceof NumberOrdering;
}
private static final long serialVersionUID = 0;
}
/*
* Now we have monster tests that create hundreds of Orderings using different
* combinations of methods, then checks compare(), binarySearch() and so
* forth on each one.
*/
// should periodically try increasing this, but it makes the test run long
private static final int RECURSE_DEPTH = 2;
public void testCombinationsExhaustively_startingFromNatural() {
testExhaustively(Ordering.<String>natural(), Arrays.asList("a", "b"));
}
public void testCombinationsExhaustively_startingFromExplicit() {
testExhaustively(Ordering.explicit("a", "b", "c", "d"),
Arrays.asList("b", "d"));
}
public void testCombinationsExhaustively_startingFromUsingToString() {
testExhaustively(Ordering.usingToString(), Arrays.asList(1, 12, 2));
}
private static <T> void testExhaustively(
Ordering<? super T> ordering, List<T> list) {
// shoot me, but I didn't want to deal with wildcards through the whole test
@SuppressWarnings("unchecked")
Scenario<T> starter = new Scenario<T>((Ordering) ordering, list);
verifyScenario(starter, 0);
}
private static <T> void verifyScenario(Scenario<T> scenario, int level) {
scenario.testCompareTo();
scenario.testIsOrdered();
scenario.testMinAndMax();
scenario.testBinarySearch();
if (level < RECURSE_DEPTH) {
for (OrderingMutation alteration : OrderingMutation.values()) {
verifyScenario(alteration.mutate(scenario), level + 1);
}
}
}
/**
* An aggregation of an ordering with a list (of size > 1) that should prove
* to be in strictly increasing order according to that ordering.
*/
private static class Scenario<T> {
final Ordering<T> ordering;
final List<T> strictlyOrderedList;
Scenario(Ordering<T> ordering, List<T> strictlyOrderedList) {
this.ordering = ordering;
this.strictlyOrderedList = strictlyOrderedList;
}
void testCompareTo() {
Helpers.testComparator(ordering, strictlyOrderedList);
}
void testIsOrdered() {
assertTrue(ordering.isOrdered(strictlyOrderedList));
assertTrue(ordering.isStrictlyOrdered(strictlyOrderedList));
}
void testMinAndMax() {
List<T> shuffledList = Lists.newArrayList(strictlyOrderedList);
Collections.shuffle(shuffledList, new Random(5));
assertEquals(strictlyOrderedList.get(0), ordering.min(shuffledList));
assertEquals(strictlyOrderedList.get(strictlyOrderedList.size() - 1),
ordering.max(shuffledList));
}
void testBinarySearch() {
for (int i = 0; i < strictlyOrderedList.size(); i++) {
assertEquals(i, ordering.binarySearch(
strictlyOrderedList, strictlyOrderedList.get(i)));
}
List<T> newList = Lists.newArrayList(strictlyOrderedList);
T valueNotInList = newList.remove(1);
assertEquals(-2, ordering.binarySearch(newList, valueNotInList));
}
}
/**
* A means for changing an Ordering into another Ordering. Each instance is
* responsible for creating the alternate Ordering, and providing a List that
* is known to be ordered, based on an input List known to be ordered
* according to the input Ordering.
*/
private enum OrderingMutation {
REVERSE {
<T> Scenario<?> mutate(Scenario<T> scenario) {
List<T> newList = Lists.newArrayList(scenario.strictlyOrderedList);
Collections.reverse(newList);
return new Scenario<T>(scenario.ordering.reverse(), newList);
}
},
NULLS_FIRST {
<T> Scenario<?> mutate(Scenario<T> scenario) {
@SuppressWarnings("unchecked")
List<T> newList = Lists.newArrayList((T) null);
for (T t : scenario.strictlyOrderedList) {
if (t != null) {
newList.add(t);
}
}
return new Scenario<T>(scenario.ordering.nullsFirst(), newList);
}
},
NULLS_LAST {
<T> Scenario<?> mutate(Scenario<T> scenario) {
List<T> newList = Lists.newArrayList();
for (T t : scenario.strictlyOrderedList) {
if (t != null) {
newList.add(t);
}
}
newList.add(null);
return new Scenario<T>(scenario.ordering.nullsLast(), newList);
}
},
ON_RESULT_OF {
<T> Scenario<?> mutate(final Scenario<T> scenario) {
Ordering<Integer> ordering = scenario.ordering.onResultOf(
new Function<Integer, T>() {
public T apply(@Nullable Integer from) {
return scenario.strictlyOrderedList.get(from);
}
});
List<Integer> list = Lists.newArrayList();
for (int i = 0; i < scenario.strictlyOrderedList.size(); i++) {
list.add(i);
}
return new Scenario<Integer>(ordering, list);
}
},
COMPOUND_THIS_WITH_NATURAL {
<T> Scenario<?> mutate(Scenario<T> scenario) {
List<Composite<T>> composites = Lists.newArrayList();
for (T t : scenario.strictlyOrderedList) {
composites.add(new Composite<T>(t, 1));
composites.add(new Composite<T>(t, 2));
}
Ordering<Composite<T>> ordering =
scenario.ordering.onResultOf(Composite.<T>getValueFunction())
.compound(Ordering.natural());
return new Scenario<Composite<T>>(ordering, composites);
}
},
COMPOUND_NATURAL_WITH_THIS {
<T> Scenario<?> mutate(Scenario<T> scenario) {
List<Composite<T>> composites = Lists.newArrayList();
for (T t : scenario.strictlyOrderedList) {
composites.add(new Composite<T>(t, 1));
}
for (T t : scenario.strictlyOrderedList) {
composites.add(new Composite<T>(t, 2));
}
Ordering<Composite<T>> ordering = Ordering.natural().compound(
scenario.ordering.onResultOf(Composite.<T>getValueFunction()));
return new Scenario<Composite<T>>(ordering, composites);
}
},
;
abstract <T> Scenario<?> mutate(Scenario<T> scenario);
}
/**
* A dummy object we create so that we can have something meaningful to have
* a compound ordering over.
*/
private static class Composite<T> implements Comparable<Composite<T>> {
final T value;
final int rank;
Composite(T value, int rank) {
this.value = value;
this.rank = rank;
}
// natural order is by rank only; the test will compound() this with the
// order of 't'.
public int compareTo(Composite<T> that) {
return rank < that.rank ? -1 : rank > that.rank ? 1 : 0;
}
static <T> Function<Composite<T>, T> getValueFunction() {
return new Function<Composite<T>, T>() {
public T apply(Composite<T> from) {
return from.value;
}
};
}
}
public void testNullPointerExceptions() throws Exception {
NullPointerTester tester = new NullPointerTester();
tester.testAllPublicStaticMethods(Ordering.class);
// any Ordering<Object> instance should be good enough
tester.testAllPublicInstanceMethods(Ordering.usingToString());
}
}