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1 /*
2  * Copyright (C) 2012 The Guava Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.google.common.testing;
18 
19 import com.google.common.base.CharMatcher;
20 import com.google.common.base.Charsets;
21 import com.google.common.base.Equivalence;
22 import com.google.common.base.Joiner;
23 import com.google.common.base.Optional;
24 import com.google.common.base.Predicate;
25 import com.google.common.base.Splitter;
26 import com.google.common.base.Stopwatch;
27 import com.google.common.base.Ticker;
28 import com.google.common.collect.BiMap;
29 import com.google.common.collect.ClassToInstanceMap;
30 import com.google.common.collect.ImmutableBiMap;
31 import com.google.common.collect.ImmutableClassToInstanceMap;
32 import com.google.common.collect.ImmutableCollection;
33 import com.google.common.collect.ImmutableList;
34 import com.google.common.collect.ImmutableListMultimap;
35 import com.google.common.collect.ImmutableMap;
36 import com.google.common.collect.ImmutableMultimap;
37 import com.google.common.collect.ImmutableMultiset;
38 import com.google.common.collect.ImmutableSet;
39 import com.google.common.collect.ImmutableSetMultimap;
40 import com.google.common.collect.ImmutableSortedMap;
41 import com.google.common.collect.ImmutableSortedSet;
42 import com.google.common.collect.ImmutableTable;
43 import com.google.common.collect.ListMultimap;
44 import com.google.common.collect.MapConstraint;
45 import com.google.common.collect.MapDifference;
46 import com.google.common.collect.Multimap;
47 import com.google.common.collect.Multiset;
48 import com.google.common.collect.PeekingIterator;
49 import com.google.common.collect.Range;
50 import com.google.common.collect.RowSortedTable;
51 import com.google.common.collect.SetMultimap;
52 import com.google.common.collect.SortedMapDifference;
53 import com.google.common.collect.SortedMultiset;
54 import com.google.common.collect.SortedSetMultimap;
55 import com.google.common.collect.Table;
56 import com.google.common.io.ByteSink;
57 import com.google.common.io.ByteSource;
58 import com.google.common.io.CharSink;
59 import com.google.common.io.CharSource;
60 import com.google.common.primitives.UnsignedInteger;
61 import com.google.common.primitives.UnsignedLong;
62 import com.google.common.util.concurrent.AtomicDouble;
63 
64 import junit.framework.TestCase;
65 
66 import java.io.ByteArrayInputStream;
67 import java.io.ByteArrayOutputStream;
68 import java.io.File;
69 import java.io.IOException;
70 import java.io.InputStream;
71 import java.io.OutputStream;
72 import java.io.PrintStream;
73 import java.io.PrintWriter;
74 import java.io.Reader;
75 import java.io.StringReader;
76 import java.io.StringWriter;
77 import java.io.Writer;
78 import java.lang.reflect.AnnotatedElement;
79 import java.lang.reflect.GenericDeclaration;
80 import java.lang.reflect.Type;
81 import java.math.BigDecimal;
82 import java.math.BigInteger;
83 import java.nio.Buffer;
84 import java.nio.ByteBuffer;
85 import java.nio.CharBuffer;
86 import java.nio.DoubleBuffer;
87 import java.nio.FloatBuffer;
88 import java.nio.IntBuffer;
89 import java.nio.LongBuffer;
90 import java.nio.ShortBuffer;
91 import java.nio.charset.Charset;
92 import java.util.ArrayList;
93 import java.util.BitSet;
94 import java.util.Collection;
95 import java.util.Comparator;
96 import java.util.Currency;
97 import java.util.Deque;
98 import java.util.HashMap;
99 import java.util.Iterator;
100 import java.util.LinkedList;
101 import java.util.List;
102 import java.util.ListIterator;
103 import java.util.Locale;
104 import java.util.Map;
105 import java.util.NavigableMap;
106 import java.util.NavigableSet;
107 import java.util.PriorityQueue;
108 import java.util.Queue;
109 import java.util.Random;
110 import java.util.Set;
111 import java.util.SortedMap;
112 import java.util.SortedSet;
113 import java.util.TreeMap;
114 import java.util.TreeSet;
115 import java.util.concurrent.BlockingDeque;
116 import java.util.concurrent.BlockingQueue;
117 import java.util.concurrent.ConcurrentMap;
118 import java.util.concurrent.ConcurrentNavigableMap;
119 import java.util.concurrent.DelayQueue;
120 import java.util.concurrent.Executor;
121 import java.util.concurrent.PriorityBlockingQueue;
122 import java.util.concurrent.SynchronousQueue;
123 import java.util.concurrent.ThreadFactory;
124 import java.util.concurrent.TimeUnit;
125 import java.util.concurrent.atomic.AtomicBoolean;
126 import java.util.concurrent.atomic.AtomicInteger;
127 import java.util.concurrent.atomic.AtomicLong;
128 import java.util.concurrent.atomic.AtomicReference;
129 import java.util.regex.MatchResult;
130 import java.util.regex.Pattern;
131 
132 /**
133  * Unit test for {@link ArbitraryInstances}.
134  *
135  * @author Ben Yu
136  */
137 public class ArbitraryInstancesTest extends TestCase {
138 
testGet_primitives()139   public void testGet_primitives() {
140     assertNull(ArbitraryInstances.get(void.class));
141     assertNull(ArbitraryInstances.get(Void.class));
142     assertEquals(Boolean.FALSE, ArbitraryInstances.get(boolean.class));
143     assertEquals(Boolean.FALSE, ArbitraryInstances.get(Boolean.class));
144     assertEquals(Character.valueOf('\0'), ArbitraryInstances.get(char.class));
145     assertEquals(Character.valueOf('\0'), ArbitraryInstances.get(Character.class));
146     assertEquals(Byte.valueOf((byte) 0), ArbitraryInstances.get(byte.class));
147     assertEquals(Byte.valueOf((byte) 0), ArbitraryInstances.get(Byte.class));
148     assertEquals(Short.valueOf((short) 0), ArbitraryInstances.get(short.class));
149     assertEquals(Short.valueOf((short) 0), ArbitraryInstances.get(Short.class));
150     assertEquals(Integer.valueOf(0), ArbitraryInstances.get(int.class));
151     assertEquals(Integer.valueOf(0), ArbitraryInstances.get(Integer.class));
152     assertEquals(Long.valueOf(0), ArbitraryInstances.get(long.class));
153     assertEquals(Long.valueOf(0), ArbitraryInstances.get(Long.class));
154     assertEquals(Float.valueOf(0), ArbitraryInstances.get(float.class));
155     assertEquals(Float.valueOf(0), ArbitraryInstances.get(Float.class));
156     assertEquals(Double.valueOf(0), ArbitraryInstances.get(double.class));
157     assertEquals(Double.valueOf(0), ArbitraryInstances.get(Double.class));
158     assertEquals(UnsignedInteger.ZERO, ArbitraryInstances.get(UnsignedInteger.class));
159     assertEquals(UnsignedLong.ZERO, ArbitraryInstances.get(UnsignedLong.class));
160     assertEquals(0, ArbitraryInstances.get(BigDecimal.class).intValue());
161     assertEquals(0, ArbitraryInstances.get(BigInteger.class).intValue());
162     assertEquals("", ArbitraryInstances.get(String.class));
163     assertEquals("", ArbitraryInstances.get(CharSequence.class));
164     assertEquals(TimeUnit.SECONDS, ArbitraryInstances.get(TimeUnit.class));
165     assertNotNull(ArbitraryInstances.get(Object.class));
166     assertEquals(0, ArbitraryInstances.get(Number.class));
167     assertEquals(Charsets.UTF_8, ArbitraryInstances.get(Charset.class));
168   }
169 
testGet_collections()170   public void testGet_collections() {
171     assertEquals(ImmutableSet.of().iterator(), ArbitraryInstances.get(Iterator.class));
172     assertFalse(ArbitraryInstances.get(PeekingIterator.class).hasNext());
173     assertFalse(ArbitraryInstances.get(ListIterator.class).hasNext());
174     assertEquals(ImmutableSet.of(), ArbitraryInstances.get(Iterable.class));
175     assertEquals(ImmutableSet.of(), ArbitraryInstances.get(Set.class));
176     assertEquals(ImmutableSet.of(), ArbitraryInstances.get(ImmutableSet.class));
177     assertEquals(ImmutableSortedSet.of(), ArbitraryInstances.get(SortedSet.class));
178     assertEquals(ImmutableSortedSet.of(), ArbitraryInstances.get(ImmutableSortedSet.class));
179     assertEquals(ImmutableList.of(), ArbitraryInstances.get(Collection.class));
180     assertEquals(ImmutableList.of(), ArbitraryInstances.get(ImmutableCollection.class));
181     assertEquals(ImmutableList.of(), ArbitraryInstances.get(List.class));
182     assertEquals(ImmutableList.of(), ArbitraryInstances.get(ImmutableList.class));
183     assertEquals(ImmutableMap.of(), ArbitraryInstances.get(Map.class));
184     assertEquals(ImmutableMap.of(), ArbitraryInstances.get(ImmutableMap.class));
185     assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(SortedMap.class));
186     assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(ImmutableSortedMap.class));
187     assertEquals(ImmutableMultiset.of(), ArbitraryInstances.get(Multiset.class));
188     assertEquals(ImmutableMultiset.of(), ArbitraryInstances.get(ImmutableMultiset.class));
189     assertTrue(ArbitraryInstances.get(SortedMultiset.class).isEmpty());
190     assertEquals(ImmutableMultimap.of(), ArbitraryInstances.get(Multimap.class));
191     assertEquals(ImmutableMultimap.of(), ArbitraryInstances.get(ImmutableMultimap.class));
192     assertTrue(ArbitraryInstances.get(SortedSetMultimap.class).isEmpty());
193     assertEquals(ImmutableTable.of(), ArbitraryInstances.get(Table.class));
194     assertEquals(ImmutableTable.of(), ArbitraryInstances.get(ImmutableTable.class));
195     assertTrue(ArbitraryInstances.get(RowSortedTable.class).isEmpty());
196     assertEquals(ImmutableBiMap.of(), ArbitraryInstances.get(BiMap.class));
197     assertEquals(ImmutableBiMap.of(), ArbitraryInstances.get(ImmutableBiMap.class));
198     assertTrue(ArbitraryInstances.get(ImmutableClassToInstanceMap.class).isEmpty());
199     assertTrue(ArbitraryInstances.get(ClassToInstanceMap.class).isEmpty());
200     assertTrue(ArbitraryInstances.get(ListMultimap.class).isEmpty());
201     assertTrue(ArbitraryInstances.get(ImmutableListMultimap.class).isEmpty());
202     assertTrue(ArbitraryInstances.get(SetMultimap.class).isEmpty());
203     assertTrue(ArbitraryInstances.get(ImmutableSetMultimap.class).isEmpty());
204     assertTrue(ArbitraryInstances.get(MapDifference.class).areEqual());
205     assertTrue(ArbitraryInstances.get(SortedMapDifference.class).areEqual());
206     assertEquals(Range.all(), ArbitraryInstances.get(Range.class));
207     assertTrue(ArbitraryInstances.get(NavigableSet.class).isEmpty());
208     assertTrue(ArbitraryInstances.get(NavigableMap.class).isEmpty());
209     assertTrue(ArbitraryInstances.get(LinkedList.class).isEmpty());
210     assertTrue(ArbitraryInstances.get(Deque.class).isEmpty());
211     assertTrue(ArbitraryInstances.get(Queue.class).isEmpty());
212     assertTrue(ArbitraryInstances.get(PriorityQueue.class).isEmpty());
213     assertTrue(ArbitraryInstances.get(BitSet.class).isEmpty());
214     assertTrue(ArbitraryInstances.get(TreeSet.class).isEmpty());
215     assertTrue(ArbitraryInstances.get(TreeMap.class).isEmpty());
216     assertFreshInstanceReturned(
217         LinkedList.class, Deque.class, Queue.class, PriorityQueue.class, BitSet.class,
218         TreeSet.class, TreeMap.class);
219   }
220 
testGet_misc()221   public void testGet_misc() {
222     assertNotNull(ArbitraryInstances.get(CharMatcher.class));
223     assertNotNull(ArbitraryInstances.get(Currency.class).getCurrencyCode());
224     assertNotNull(ArbitraryInstances.get(Locale.class));
225     ArbitraryInstances.get(Joiner.class).join(ImmutableList.of("a"));
226     ArbitraryInstances.get(Splitter.class).split("a,b");
227     assertFalse(ArbitraryInstances.get(Optional.class).isPresent());
228     ArbitraryInstances.get(Stopwatch.class).start();
229     assertNotNull(ArbitraryInstances.get(Ticker.class));
230     assertNotNull(ArbitraryInstances.get(MapConstraint.class));
231     assertFreshInstanceReturned(Random.class);
232     assertEquals(ArbitraryInstances.get(Random.class).nextInt(),
233         ArbitraryInstances.get(Random.class).nextInt());
234   }
235 
testGet_concurrent()236   public void testGet_concurrent() {
237     assertTrue(ArbitraryInstances.get(BlockingDeque.class).isEmpty());
238     assertTrue(ArbitraryInstances.get(BlockingQueue.class).isEmpty());
239     assertTrue(ArbitraryInstances.get(DelayQueue.class).isEmpty());
240     assertTrue(ArbitraryInstances.get(SynchronousQueue.class).isEmpty());
241     assertTrue(ArbitraryInstances.get(PriorityBlockingQueue.class).isEmpty());
242     assertTrue(ArbitraryInstances.get(ConcurrentMap.class).isEmpty());
243     assertTrue(ArbitraryInstances.get(ConcurrentNavigableMap.class).isEmpty());
244     ArbitraryInstances.get(Executor.class).execute(ArbitraryInstances.get(Runnable.class));
245     assertNotNull(ArbitraryInstances.get(ThreadFactory.class));
246     assertFreshInstanceReturned(
247         BlockingQueue.class, BlockingDeque.class, PriorityBlockingQueue.class,
248         DelayQueue.class, SynchronousQueue.class,
249         ConcurrentMap.class, ConcurrentNavigableMap.class,
250         AtomicReference.class, AtomicBoolean.class,
251         AtomicInteger.class, AtomicLong.class, AtomicDouble.class);
252   }
253 
254   @SuppressWarnings("unchecked") // functor classes have no type parameters
testGet_functors()255   public void testGet_functors() {
256     assertEquals(0, ArbitraryInstances.get(Comparator.class).compare("abc", 123));
257     assertTrue(ArbitraryInstances.get(Predicate.class).apply("abc"));
258     assertTrue(ArbitraryInstances.get(Equivalence.class).equivalent(1, 1));
259     assertFalse(ArbitraryInstances.get(Equivalence.class).equivalent(1, 2));
260   }
261 
testGet_comparable()262   public void testGet_comparable() {
263     @SuppressWarnings("unchecked") // The null value can compare with any Object
264     Comparable<Object> comparable = ArbitraryInstances.get(Comparable.class);
265     assertEquals(0, comparable.compareTo(comparable));
266     assertTrue(comparable.compareTo("") > 0);
267     try {
268       comparable.compareTo(null);
269       fail();
270     } catch (NullPointerException expected) {}
271   }
272 
testGet_array()273   public void testGet_array() {
274     assertEquals(0, ArbitraryInstances.get(int[].class).length);
275     assertEquals(0, ArbitraryInstances.get(Object[].class).length);
276     assertEquals(0, ArbitraryInstances.get(String[].class).length);
277   }
278 
testGet_enum()279   public void testGet_enum() {
280     assertNull(ArbitraryInstances.get(EmptyEnum.class));
281     assertEquals(Direction.UP, ArbitraryInstances.get(Direction.class));
282   }
283 
testGet_interface()284   public void testGet_interface() {
285     assertNull(ArbitraryInstances.get(SomeInterface.class));
286   }
287 
testGet_runnable()288   public void testGet_runnable() {
289     ArbitraryInstances.get(Runnable.class).run();
290   }
291 
testGet_class()292   public void testGet_class() {
293     assertSame(SomeAbstractClass.INSTANCE, ArbitraryInstances.get(SomeAbstractClass.class));
294     assertSame(WithPrivateConstructor.INSTANCE,
295         ArbitraryInstances.get(WithPrivateConstructor.class));
296     assertNull(ArbitraryInstances.get(NoDefaultConstructor.class));
297     assertSame(WithExceptionalConstructor.INSTANCE,
298         ArbitraryInstances.get(WithExceptionalConstructor.class));
299     assertNull(ArbitraryInstances.get(NonPublicClass.class));
300   }
301 
testGet_mutable()302   public void testGet_mutable() {
303     assertEquals(0, ArbitraryInstances.get(ArrayList.class).size());
304     assertEquals(0, ArbitraryInstances.get(HashMap.class).size());
305     assertEquals("", ArbitraryInstances.get(Appendable.class).toString());
306     assertEquals("", ArbitraryInstances.get(StringBuilder.class).toString());
307     assertEquals("", ArbitraryInstances.get(StringBuffer.class).toString());
308     assertFreshInstanceReturned(
309         ArrayList.class, HashMap.class,
310         Appendable.class, StringBuilder.class, StringBuffer.class,
311         Throwable.class, Exception.class);
312   }
313 
testGet_io()314   public void testGet_io() throws IOException {
315     assertEquals(-1, ArbitraryInstances.get(InputStream.class).read());
316     assertEquals(-1, ArbitraryInstances.get(ByteArrayInputStream.class).read());
317     assertEquals(-1, ArbitraryInstances.get(Readable.class).read(CharBuffer.allocate(1)));
318     assertEquals(-1, ArbitraryInstances.get(Reader.class).read());
319     assertEquals(-1, ArbitraryInstances.get(StringReader.class).read());
320     assertEquals(0, ArbitraryInstances.get(Buffer.class).capacity());
321     assertEquals(0, ArbitraryInstances.get(CharBuffer.class).capacity());
322     assertEquals(0, ArbitraryInstances.get(ByteBuffer.class).capacity());
323     assertEquals(0, ArbitraryInstances.get(ShortBuffer.class).capacity());
324     assertEquals(0, ArbitraryInstances.get(IntBuffer.class).capacity());
325     assertEquals(0, ArbitraryInstances.get(LongBuffer.class).capacity());
326     assertEquals(0, ArbitraryInstances.get(FloatBuffer.class).capacity());
327     assertEquals(0, ArbitraryInstances.get(DoubleBuffer.class).capacity());
328     ArbitraryInstances.get(PrintStream.class).println("test");
329     ArbitraryInstances.get(PrintWriter.class).println("test");
330     assertNotNull(ArbitraryInstances.get(File.class));
331     assertFreshInstanceReturned(
332         ByteArrayOutputStream.class, OutputStream.class,
333         Writer.class, StringWriter.class,
334         PrintStream.class, PrintWriter.class);
335     assertEquals(ByteSource.empty(), ArbitraryInstances.get(ByteSource.class));
336     assertEquals(CharSource.empty(), ArbitraryInstances.get(CharSource.class));
337     assertNotNull(ArbitraryInstances.get(ByteSink.class));
338     assertNotNull(ArbitraryInstances.get(CharSink.class));
339   }
340 
testGet_reflect()341   public void testGet_reflect() {
342     assertNotNull(ArbitraryInstances.get(Type.class));
343     assertNotNull(ArbitraryInstances.get(AnnotatedElement.class));
344     assertNotNull(ArbitraryInstances.get(GenericDeclaration.class));
345   }
346 
testGet_regex()347   public void testGet_regex() {
348     assertEquals(Pattern.compile("").pattern(),
349         ArbitraryInstances.get(Pattern.class).pattern());
350     assertEquals(0, ArbitraryInstances.get(MatchResult.class).groupCount());
351   }
352 
testGet_usePublicConstant()353   public void testGet_usePublicConstant() {
354     assertSame(WithPublicConstant.INSTANCE,
355         ArbitraryInstances.get(WithPublicConstant.class));
356   }
357 
testGet_useFirstPublicConstant()358   public void testGet_useFirstPublicConstant() {
359     assertSame(WithPublicConstants.FIRST,
360         ArbitraryInstances.get(WithPublicConstants.class));
361   }
362 
testGet_nullConstantIgnored()363   public void testGet_nullConstantIgnored() {
364     assertSame(FirstConstantIsNull.SECOND,
365         ArbitraryInstances.get(FirstConstantIsNull.class));
366   }
367 
testGet_constantWithGenericsNotUsed()368   public void testGet_constantWithGenericsNotUsed() {
369     assertNull(ArbitraryInstances.get(WithGenericConstant.class));
370   }
371 
testGet_nullConstant()372   public void testGet_nullConstant() {
373     assertNull(ArbitraryInstances.get(WithNullConstant.class));
374   }
375 
testGet_constantTypeDoesNotMatch()376   public void testGet_constantTypeDoesNotMatch() {
377     assertNull(ArbitraryInstances.get(ParentClassHasConstant.class));
378   }
379 
testGet_nonPublicConstantNotUsed()380   public void testGet_nonPublicConstantNotUsed() {
381     assertNull(ArbitraryInstances.get(NonPublicConstantIgnored.class));
382   }
383 
testGet_nonStaticFieldNotUsed()384   public void testGet_nonStaticFieldNotUsed() {
385     assertNull(ArbitraryInstances.get(NonStaticFieldIgnored.class));
386   }
387 
testGet_constructorPreferredOverConstants()388   public void testGet_constructorPreferredOverConstants() {
389     assertNotNull(ArbitraryInstances.get(WithPublicConstructorAndConstant.class));
390     assertTrue(ArbitraryInstances.get(WithPublicConstructorAndConstant.class)
391         != ArbitraryInstances.get(WithPublicConstructorAndConstant.class));
392   }
393 
testGet_nonFinalFieldNotUsed()394   public void testGet_nonFinalFieldNotUsed() {
395     assertNull(ArbitraryInstances.get(NonFinalFieldIgnored.class));
396   }
397 
assertFreshInstanceReturned(Class<?>.... mutableClasses)398   private static void assertFreshInstanceReturned(Class<?>... mutableClasses) {
399     for (Class<?> mutableClass : mutableClasses) {
400       Object instance = ArbitraryInstances.get(mutableClass);
401       assertNotNull("Expected to return non-null for: " + mutableClass, instance);
402       assertNotSame("Expected to return fresh instance for: " + mutableClass,
403           instance, ArbitraryInstances.get(mutableClass));
404     }
405   }
406 
407   private enum EmptyEnum {}
408 
409   private enum Direction {
410     UP, DOWN
411   }
412 
413   public interface SomeInterface {}
414 
415   public static abstract class SomeAbstractClass {
416     public static final SomeAbstractClass INSTANCE = new SomeAbstractClass() {};
SomeAbstractClass()417     public SomeAbstractClass() {}
418   }
419 
420   static class NonPublicClass {
NonPublicClass()421     public NonPublicClass() {}
422   }
423 
424   private static class WithPrivateConstructor {
425     public static final WithPrivateConstructor INSTANCE = new WithPrivateConstructor();
426   }
427 
428   public static class NoDefaultConstructor {
NoDefaultConstructor(@uppressWarnings"unused") int i)429     public NoDefaultConstructor(@SuppressWarnings("unused") int i) {}
430   }
431 
432   public static class WithExceptionalConstructor {
433     public static final WithExceptionalConstructor INSTANCE =
434         new WithExceptionalConstructor("whatever");
435 
WithExceptionalConstructor()436     public WithExceptionalConstructor() {
437       throw new RuntimeException();
438     }
WithExceptionalConstructor(String unused)439     private WithExceptionalConstructor(String unused) {}
440   }
441 
442   private static class WithPublicConstant {
443     public static final WithPublicConstant INSTANCE = new WithPublicConstant();
444   }
445 
446   private static class ParentClassHasConstant
447       extends WithPublicConstant {}
448 
449   public static class WithGenericConstant<T> {
450     public static final WithGenericConstant<String> STRING_CONSTANT =
451         new WithGenericConstant<String>();
452 
WithGenericConstant()453     private WithGenericConstant() {}
454   }
455 
456   public static class WithNullConstant {
457     public static final WithNullConstant NULL = null;
458 
WithNullConstant()459     private WithNullConstant() {}
460   }
461 
462   public static class WithPublicConstructorAndConstant {
463     public static final WithPublicConstructorAndConstant INSTANCE =
464         new WithPublicConstructorAndConstant();
465 
WithPublicConstructorAndConstant()466     public WithPublicConstructorAndConstant() {}
467   }
468 
469   private static class WithPublicConstants {
470     public static final WithPublicConstants FIRST = new WithPublicConstants();
471 
472     // To test that we pick the first constant alphabetically
473     @SuppressWarnings("unused")
474     public static final WithPublicConstants SECOND = new WithPublicConstants();
475   }
476 
477   private static class FirstConstantIsNull {
478     // To test that null constant is ignored
479     @SuppressWarnings("unused")
480     public static final FirstConstantIsNull FIRST = null;
481     public static final FirstConstantIsNull SECOND = new FirstConstantIsNull();
482   }
483 
484   public static class NonFinalFieldIgnored {
485     public static NonFinalFieldIgnored instance =
486         new NonFinalFieldIgnored();
487 
NonFinalFieldIgnored()488     private NonFinalFieldIgnored() {}
489   }
490 
491   public static class NonPublicConstantIgnored {
492     static final NonPublicConstantIgnored INSTANCE =
493         new NonPublicConstantIgnored();
494 
NonPublicConstantIgnored()495     private NonPublicConstantIgnored() {}
496   }
497 
498   public static class NonStaticFieldIgnored {
499     // This should cause infinite recursion. But it shouldn't be used anyway.
500     public final NonStaticFieldIgnored instance =
501         new NonStaticFieldIgnored();
502 
NonStaticFieldIgnored()503     private NonStaticFieldIgnored() {}
504   }
505 }
506