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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 static com.google.common.truth.Truth.assertThat;
20 
21 import com.google.common.base.CharMatcher;
22 import com.google.common.base.Charsets;
23 import com.google.common.base.Equivalence;
24 import com.google.common.base.Joiner;
25 import com.google.common.base.Predicate;
26 import com.google.common.base.Splitter;
27 import com.google.common.base.Stopwatch;
28 import com.google.common.base.Ticker;
29 import com.google.common.collect.BiMap;
30 import com.google.common.collect.ClassToInstanceMap;
31 import com.google.common.collect.ImmutableBiMap;
32 import com.google.common.collect.ImmutableClassToInstanceMap;
33 import com.google.common.collect.ImmutableCollection;
34 import com.google.common.collect.ImmutableList;
35 import com.google.common.collect.ImmutableListMultimap;
36 import com.google.common.collect.ImmutableMap;
37 import com.google.common.collect.ImmutableMultimap;
38 import com.google.common.collect.ImmutableMultiset;
39 import com.google.common.collect.ImmutableSet;
40 import com.google.common.collect.ImmutableSetMultimap;
41 import com.google.common.collect.ImmutableSortedMap;
42 import com.google.common.collect.ImmutableSortedSet;
43 import com.google.common.collect.ImmutableTable;
44 import com.google.common.collect.ListMultimap;
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 import java.io.ByteArrayInputStream;
64 import java.io.ByteArrayOutputStream;
65 import java.io.File;
66 import java.io.IOException;
67 import java.io.InputStream;
68 import java.io.OutputStream;
69 import java.io.PrintStream;
70 import java.io.PrintWriter;
71 import java.io.Reader;
72 import java.io.StringReader;
73 import java.io.StringWriter;
74 import java.io.Writer;
75 import java.lang.reflect.AnnotatedElement;
76 import java.lang.reflect.GenericDeclaration;
77 import java.lang.reflect.Type;
78 import java.math.BigDecimal;
79 import java.math.BigInteger;
80 import java.nio.Buffer;
81 import java.nio.ByteBuffer;
82 import java.nio.CharBuffer;
83 import java.nio.DoubleBuffer;
84 import java.nio.FloatBuffer;
85 import java.nio.IntBuffer;
86 import java.nio.LongBuffer;
87 import java.nio.ShortBuffer;
88 import java.nio.charset.Charset;
89 import java.util.ArrayList;
90 import java.util.BitSet;
91 import java.util.Collection;
92 import java.util.Comparator;
93 import java.util.Currency;
94 import java.util.Deque;
95 import java.util.HashMap;
96 import java.util.Iterator;
97 import java.util.LinkedList;
98 import java.util.List;
99 import java.util.ListIterator;
100 import java.util.Locale;
101 import java.util.Map;
102 import java.util.NavigableMap;
103 import java.util.NavigableSet;
104 import java.util.PriorityQueue;
105 import java.util.Queue;
106 import java.util.Random;
107 import java.util.Set;
108 import java.util.SortedMap;
109 import java.util.SortedSet;
110 import java.util.TreeMap;
111 import java.util.TreeSet;
112 import java.util.UUID;
113 import java.util.concurrent.BlockingDeque;
114 import java.util.concurrent.BlockingQueue;
115 import java.util.concurrent.ConcurrentMap;
116 import java.util.concurrent.ConcurrentNavigableMap;
117 import java.util.concurrent.DelayQueue;
118 import java.util.concurrent.Executor;
119 import java.util.concurrent.PriorityBlockingQueue;
120 import java.util.concurrent.SynchronousQueue;
121 import java.util.concurrent.ThreadFactory;
122 import java.util.concurrent.TimeUnit;
123 import java.util.concurrent.atomic.AtomicBoolean;
124 import java.util.concurrent.atomic.AtomicInteger;
125 import java.util.concurrent.atomic.AtomicLong;
126 import java.util.concurrent.atomic.AtomicReference;
127 import java.util.regex.MatchResult;
128 import java.util.regex.Pattern;
129 import junit.framework.TestCase;
130 
131 /**
132  * Unit test for {@link ArbitraryInstances}.
133  *
134  * @author Ben Yu
135  */
136 public class ArbitraryInstancesTest extends TestCase {
137 
testGet_primitives()138   public void testGet_primitives() {
139     assertNull(ArbitraryInstances.get(void.class));
140     assertNull(ArbitraryInstances.get(Void.class));
141     assertEquals(Boolean.FALSE, ArbitraryInstances.get(boolean.class));
142     assertEquals(Boolean.FALSE, ArbitraryInstances.get(Boolean.class));
143     assertEquals(Character.valueOf('\0'), ArbitraryInstances.get(char.class));
144     assertEquals(Character.valueOf('\0'), ArbitraryInstances.get(Character.class));
145     assertEquals(Byte.valueOf((byte) 0), ArbitraryInstances.get(byte.class));
146     assertEquals(Byte.valueOf((byte) 0), ArbitraryInstances.get(Byte.class));
147     assertEquals(Short.valueOf((short) 0), ArbitraryInstances.get(short.class));
148     assertEquals(Short.valueOf((short) 0), ArbitraryInstances.get(Short.class));
149     assertEquals(Integer.valueOf(0), ArbitraryInstances.get(int.class));
150     assertEquals(Integer.valueOf(0), ArbitraryInstances.get(Integer.class));
151     assertEquals(Long.valueOf(0), ArbitraryInstances.get(long.class));
152     assertEquals(Long.valueOf(0), ArbitraryInstances.get(Long.class));
153     assertEquals(Float.valueOf(0), ArbitraryInstances.get(float.class));
154     assertEquals(Float.valueOf(0), ArbitraryInstances.get(Float.class));
155     assertEquals(Double.valueOf(0), ArbitraryInstances.get(double.class));
156     assertEquals(Double.valueOf(0), ArbitraryInstances.get(Double.class));
157     assertEquals(UnsignedInteger.ZERO, ArbitraryInstances.get(UnsignedInteger.class));
158     assertEquals(UnsignedLong.ZERO, ArbitraryInstances.get(UnsignedLong.class));
159     assertEquals(0, ArbitraryInstances.get(BigDecimal.class).intValue());
160     assertEquals(0, ArbitraryInstances.get(BigInteger.class).intValue());
161     assertEquals("", ArbitraryInstances.get(String.class));
162     assertEquals("", ArbitraryInstances.get(CharSequence.class));
163     assertEquals(TimeUnit.SECONDS, ArbitraryInstances.get(TimeUnit.class));
164     assertNotNull(ArbitraryInstances.get(Object.class));
165     assertEquals(0, ArbitraryInstances.get(Number.class));
166     assertEquals(Charsets.UTF_8, ArbitraryInstances.get(Charset.class));
167     assertNotNull(ArbitraryInstances.get(UUID.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,
218         Deque.class,
219         Queue.class,
220         PriorityQueue.class,
221         BitSet.class,
222         TreeSet.class,
223         TreeMap.class);
224   }
225 
testGet_misc()226   public void testGet_misc() {
227     assertNotNull(ArbitraryInstances.get(CharMatcher.class));
228     assertNotNull(ArbitraryInstances.get(Currency.class).getCurrencyCode());
229     assertNotNull(ArbitraryInstances.get(Locale.class));
230     assertNotNull(ArbitraryInstances.get(Joiner.class).join(ImmutableList.of("a")));
231     assertNotNull(ArbitraryInstances.get(Splitter.class).split("a,b"));
232     assertThat(ArbitraryInstances.get(com.google.common.base.Optional.class)).isAbsent();
233     ArbitraryInstances.get(Stopwatch.class).start();
234     assertNotNull(ArbitraryInstances.get(Ticker.class));
235     assertFreshInstanceReturned(Random.class);
236     assertEquals(
237         ArbitraryInstances.get(Random.class).nextInt(),
238         ArbitraryInstances.get(Random.class).nextInt());
239   }
240 
testGet_concurrent()241   public void testGet_concurrent() {
242     assertTrue(ArbitraryInstances.get(BlockingDeque.class).isEmpty());
243     assertTrue(ArbitraryInstances.get(BlockingQueue.class).isEmpty());
244     assertTrue(ArbitraryInstances.get(DelayQueue.class).isEmpty());
245     assertTrue(ArbitraryInstances.get(SynchronousQueue.class).isEmpty());
246     assertTrue(ArbitraryInstances.get(PriorityBlockingQueue.class).isEmpty());
247     assertTrue(ArbitraryInstances.get(ConcurrentMap.class).isEmpty());
248     assertTrue(ArbitraryInstances.get(ConcurrentNavigableMap.class).isEmpty());
249     ArbitraryInstances.get(Executor.class).execute(ArbitraryInstances.get(Runnable.class));
250     assertNotNull(ArbitraryInstances.get(ThreadFactory.class));
251     assertFreshInstanceReturned(
252         BlockingQueue.class,
253         BlockingDeque.class,
254         PriorityBlockingQueue.class,
255         DelayQueue.class,
256         SynchronousQueue.class,
257         ConcurrentMap.class,
258         ConcurrentNavigableMap.class,
259         AtomicReference.class,
260         AtomicBoolean.class,
261         AtomicInteger.class,
262         AtomicLong.class,
263         AtomicDouble.class);
264   }
265 
266   @SuppressWarnings("unchecked") // functor classes have no type parameters
testGet_functors()267   public void testGet_functors() {
268     assertEquals(0, ArbitraryInstances.get(Comparator.class).compare("abc", 123));
269     assertTrue(ArbitraryInstances.get(Predicate.class).apply("abc"));
270     assertTrue(ArbitraryInstances.get(Equivalence.class).equivalent(1, 1));
271     assertFalse(ArbitraryInstances.get(Equivalence.class).equivalent(1, 2));
272   }
273 
274   @SuppressWarnings("SelfComparison")
testGet_comparable()275   public void testGet_comparable() {
276     @SuppressWarnings("unchecked") // The null value can compare with any Object
277     Comparable<Object> comparable = ArbitraryInstances.get(Comparable.class);
278     assertEquals(0, comparable.compareTo(comparable));
279     assertTrue(comparable.compareTo("") > 0);
280     try {
281       comparable.compareTo(null);
282       fail();
283     } catch (NullPointerException expected) {
284     }
285   }
286 
testGet_array()287   public void testGet_array() {
288     assertThat(ArbitraryInstances.get(int[].class)).isEmpty();
289     assertThat(ArbitraryInstances.get(Object[].class)).isEmpty();
290     assertThat(ArbitraryInstances.get(String[].class)).isEmpty();
291   }
292 
testGet_enum()293   public void testGet_enum() {
294     assertNull(ArbitraryInstances.get(EmptyEnum.class));
295     assertEquals(Direction.UP, ArbitraryInstances.get(Direction.class));
296   }
297 
testGet_interface()298   public void testGet_interface() {
299     assertNull(ArbitraryInstances.get(SomeInterface.class));
300   }
301 
testGet_runnable()302   public void testGet_runnable() {
303     ArbitraryInstances.get(Runnable.class).run();
304   }
305 
testGet_class()306   public void testGet_class() {
307     assertSame(SomeAbstractClass.INSTANCE, ArbitraryInstances.get(SomeAbstractClass.class));
308     assertSame(
309         WithPrivateConstructor.INSTANCE, ArbitraryInstances.get(WithPrivateConstructor.class));
310     assertNull(ArbitraryInstances.get(NoDefaultConstructor.class));
311     assertSame(
312         WithExceptionalConstructor.INSTANCE,
313         ArbitraryInstances.get(WithExceptionalConstructor.class));
314     assertNull(ArbitraryInstances.get(NonPublicClass.class));
315   }
316 
testGet_mutable()317   public void testGet_mutable() {
318     assertEquals(0, ArbitraryInstances.get(ArrayList.class).size());
319     assertEquals(0, ArbitraryInstances.get(HashMap.class).size());
320     assertThat(ArbitraryInstances.get(Appendable.class).toString()).isEmpty();
321     assertThat(ArbitraryInstances.get(StringBuilder.class).toString()).isEmpty();
322     assertThat(ArbitraryInstances.get(StringBuffer.class).toString()).isEmpty();
323     assertFreshInstanceReturned(
324         ArrayList.class,
325         HashMap.class,
326         Appendable.class,
327         StringBuilder.class,
328         StringBuffer.class,
329         Throwable.class,
330         Exception.class);
331   }
332 
testGet_io()333   public void testGet_io() throws IOException {
334     assertEquals(-1, ArbitraryInstances.get(InputStream.class).read());
335     assertEquals(-1, ArbitraryInstances.get(ByteArrayInputStream.class).read());
336     assertEquals(-1, ArbitraryInstances.get(Readable.class).read(CharBuffer.allocate(1)));
337     assertEquals(-1, ArbitraryInstances.get(Reader.class).read());
338     assertEquals(-1, ArbitraryInstances.get(StringReader.class).read());
339     assertEquals(0, ArbitraryInstances.get(Buffer.class).capacity());
340     assertEquals(0, ArbitraryInstances.get(CharBuffer.class).capacity());
341     assertEquals(0, ArbitraryInstances.get(ByteBuffer.class).capacity());
342     assertEquals(0, ArbitraryInstances.get(ShortBuffer.class).capacity());
343     assertEquals(0, ArbitraryInstances.get(IntBuffer.class).capacity());
344     assertEquals(0, ArbitraryInstances.get(LongBuffer.class).capacity());
345     assertEquals(0, ArbitraryInstances.get(FloatBuffer.class).capacity());
346     assertEquals(0, ArbitraryInstances.get(DoubleBuffer.class).capacity());
347     ArbitraryInstances.get(PrintStream.class).println("test");
348     ArbitraryInstances.get(PrintWriter.class).println("test");
349     assertNotNull(ArbitraryInstances.get(File.class));
350     assertFreshInstanceReturned(
351         ByteArrayOutputStream.class, OutputStream.class,
352         Writer.class, StringWriter.class,
353         PrintStream.class, PrintWriter.class);
354     assertEquals(ByteSource.empty(), ArbitraryInstances.get(ByteSource.class));
355     assertEquals(CharSource.empty(), ArbitraryInstances.get(CharSource.class));
356     assertNotNull(ArbitraryInstances.get(ByteSink.class));
357     assertNotNull(ArbitraryInstances.get(CharSink.class));
358   }
359 
testGet_reflect()360   public void testGet_reflect() {
361     assertNotNull(ArbitraryInstances.get(Type.class));
362     assertNotNull(ArbitraryInstances.get(AnnotatedElement.class));
363     assertNotNull(ArbitraryInstances.get(GenericDeclaration.class));
364   }
365 
testGet_regex()366   public void testGet_regex() {
367     assertEquals(Pattern.compile("").pattern(), ArbitraryInstances.get(Pattern.class).pattern());
368     assertEquals(0, ArbitraryInstances.get(MatchResult.class).groupCount());
369   }
370 
testGet_usePublicConstant()371   public void testGet_usePublicConstant() {
372     assertSame(WithPublicConstant.INSTANCE, ArbitraryInstances.get(WithPublicConstant.class));
373   }
374 
testGet_useFirstPublicConstant()375   public void testGet_useFirstPublicConstant() {
376     assertSame(WithPublicConstants.FIRST, ArbitraryInstances.get(WithPublicConstants.class));
377   }
378 
testGet_nullConstantIgnored()379   public void testGet_nullConstantIgnored() {
380     assertSame(FirstConstantIsNull.SECOND, ArbitraryInstances.get(FirstConstantIsNull.class));
381   }
382 
testGet_constantWithGenericsNotUsed()383   public void testGet_constantWithGenericsNotUsed() {
384     assertNull(ArbitraryInstances.get(WithGenericConstant.class));
385   }
386 
testGet_nullConstant()387   public void testGet_nullConstant() {
388     assertNull(ArbitraryInstances.get(WithNullConstant.class));
389   }
390 
testGet_constantTypeDoesNotMatch()391   public void testGet_constantTypeDoesNotMatch() {
392     assertNull(ArbitraryInstances.get(ParentClassHasConstant.class));
393   }
394 
testGet_nonPublicConstantNotUsed()395   public void testGet_nonPublicConstantNotUsed() {
396     assertNull(ArbitraryInstances.get(NonPublicConstantIgnored.class));
397   }
398 
testGet_nonStaticFieldNotUsed()399   public void testGet_nonStaticFieldNotUsed() {
400     assertNull(ArbitraryInstances.get(NonStaticFieldIgnored.class));
401   }
402 
testGet_constructorPreferredOverConstants()403   public void testGet_constructorPreferredOverConstants() {
404     assertNotNull(ArbitraryInstances.get(WithPublicConstructorAndConstant.class));
405     assertTrue(
406         ArbitraryInstances.get(WithPublicConstructorAndConstant.class)
407             != ArbitraryInstances.get(WithPublicConstructorAndConstant.class));
408   }
409 
testGet_nonFinalFieldNotUsed()410   public void testGet_nonFinalFieldNotUsed() {
411     assertNull(ArbitraryInstances.get(NonFinalFieldIgnored.class));
412   }
413 
assertFreshInstanceReturned(Class<?>.... mutableClasses)414   private static void assertFreshInstanceReturned(Class<?>... mutableClasses) {
415     for (Class<?> mutableClass : mutableClasses) {
416       Object instance = ArbitraryInstances.get(mutableClass);
417       assertNotNull("Expected to return non-null for: " + mutableClass, instance);
418       assertNotSame(
419           "Expected to return fresh instance for: " + mutableClass,
420           instance,
421           ArbitraryInstances.get(mutableClass));
422     }
423   }
424 
425   private enum EmptyEnum {}
426 
427   private enum Direction {
428     UP,
429     DOWN
430   }
431 
432   public interface SomeInterface {}
433 
434   public abstract static class SomeAbstractClass {
435     public static final SomeAbstractClass INSTANCE = new SomeAbstractClass() {};
436 
SomeAbstractClass()437     public SomeAbstractClass() {}
438   }
439 
440   static class NonPublicClass {
NonPublicClass()441     public NonPublicClass() {}
442   }
443 
444   private static class WithPrivateConstructor {
445     public static final WithPrivateConstructor INSTANCE = new WithPrivateConstructor();
446   }
447 
448   public static class NoDefaultConstructor {
NoDefaultConstructor(@uppressWarnings"unused") int i)449     public NoDefaultConstructor(@SuppressWarnings("unused") int i) {}
450   }
451 
452   public static class WithExceptionalConstructor {
453     public static final WithExceptionalConstructor INSTANCE =
454         new WithExceptionalConstructor("whatever");
455 
WithExceptionalConstructor()456     public WithExceptionalConstructor() {
457       throw new RuntimeException();
458     }
459 
WithExceptionalConstructor(String unused)460     private WithExceptionalConstructor(String unused) {}
461   }
462 
463   private static class WithPublicConstant {
464     public static final WithPublicConstant INSTANCE = new WithPublicConstant();
465   }
466 
467   private static class ParentClassHasConstant extends WithPublicConstant {}
468 
469   public static class WithGenericConstant<T> {
470     public static final WithGenericConstant<String> STRING_CONSTANT = new WithGenericConstant<>();
471 
WithGenericConstant()472     private WithGenericConstant() {}
473   }
474 
475   public static class WithNullConstant {
476     public static final WithNullConstant NULL = null;
477 
WithNullConstant()478     private WithNullConstant() {}
479   }
480 
481   public static class WithPublicConstructorAndConstant {
482     public static final WithPublicConstructorAndConstant INSTANCE =
483         new WithPublicConstructorAndConstant();
484 
WithPublicConstructorAndConstant()485     public WithPublicConstructorAndConstant() {}
486   }
487 
488   private static class WithPublicConstants {
489     public static final WithPublicConstants FIRST = new WithPublicConstants();
490 
491     // To test that we pick the first constant alphabetically
492     @SuppressWarnings("unused")
493     public static final WithPublicConstants SECOND = new WithPublicConstants();
494   }
495 
496   private static class FirstConstantIsNull {
497     // To test that null constant is ignored
498     @SuppressWarnings("unused")
499     public static final FirstConstantIsNull FIRST = null;
500 
501     public static final FirstConstantIsNull SECOND = new FirstConstantIsNull();
502   }
503 
504   public static class NonFinalFieldIgnored {
505     public static NonFinalFieldIgnored instance = new NonFinalFieldIgnored();
506 
NonFinalFieldIgnored()507     private NonFinalFieldIgnored() {}
508   }
509 
510   public static class NonPublicConstantIgnored {
511     static final NonPublicConstantIgnored INSTANCE = new NonPublicConstantIgnored();
512 
NonPublicConstantIgnored()513     private NonPublicConstantIgnored() {}
514   }
515 
516   public static class NonStaticFieldIgnored {
517     // This should cause infinite recursion. But it shouldn't be used anyway.
518     public final NonStaticFieldIgnored instance = new NonStaticFieldIgnored();
519 
NonStaticFieldIgnored()520     private NonStaticFieldIgnored() {}
521   }
522 }
523