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.Optional;
105 import java.util.OptionalDouble;
106 import java.util.OptionalInt;
107 import java.util.OptionalLong;
108 import java.util.PriorityQueue;
109 import java.util.Queue;
110 import java.util.Random;
111 import java.util.Set;
112 import java.util.SortedMap;
113 import java.util.SortedSet;
114 import java.util.TreeMap;
115 import java.util.TreeSet;
116 import java.util.UUID;
117 import java.util.concurrent.BlockingDeque;
118 import java.util.concurrent.BlockingQueue;
119 import java.util.concurrent.ConcurrentMap;
120 import java.util.concurrent.ConcurrentNavigableMap;
121 import java.util.concurrent.DelayQueue;
122 import java.util.concurrent.Executor;
123 import java.util.concurrent.PriorityBlockingQueue;
124 import java.util.concurrent.SynchronousQueue;
125 import java.util.concurrent.ThreadFactory;
126 import java.util.concurrent.TimeUnit;
127 import java.util.concurrent.atomic.AtomicBoolean;
128 import java.util.concurrent.atomic.AtomicInteger;
129 import java.util.concurrent.atomic.AtomicLong;
130 import java.util.concurrent.atomic.AtomicReference;
131 import java.util.regex.MatchResult;
132 import java.util.regex.Pattern;
133 import junit.framework.TestCase;
134 
135 /**
136  * Unit test for {@link ArbitraryInstances}.
137  *
138  * @author Ben Yu
139  */
140 public class ArbitraryInstancesTest extends TestCase {
141 
testGet_primitives()142   public void testGet_primitives() {
143     assertNull(ArbitraryInstances.get(void.class));
144     assertNull(ArbitraryInstances.get(Void.class));
145     assertEquals(Boolean.FALSE, ArbitraryInstances.get(boolean.class));
146     assertEquals(Boolean.FALSE, ArbitraryInstances.get(Boolean.class));
147     assertEquals(Character.valueOf('\0'), ArbitraryInstances.get(char.class));
148     assertEquals(Character.valueOf('\0'), ArbitraryInstances.get(Character.class));
149     assertEquals(Byte.valueOf((byte) 0), ArbitraryInstances.get(byte.class));
150     assertEquals(Byte.valueOf((byte) 0), ArbitraryInstances.get(Byte.class));
151     assertEquals(Short.valueOf((short) 0), ArbitraryInstances.get(short.class));
152     assertEquals(Short.valueOf((short) 0), ArbitraryInstances.get(Short.class));
153     assertEquals(Integer.valueOf(0), ArbitraryInstances.get(int.class));
154     assertEquals(Integer.valueOf(0), ArbitraryInstances.get(Integer.class));
155     assertEquals(Long.valueOf(0), ArbitraryInstances.get(long.class));
156     assertEquals(Long.valueOf(0), ArbitraryInstances.get(Long.class));
157     assertEquals(Float.valueOf(0), ArbitraryInstances.get(float.class));
158     assertEquals(Float.valueOf(0), ArbitraryInstances.get(Float.class));
159     assertEquals(Double.valueOf(0), ArbitraryInstances.get(double.class));
160     assertEquals(Double.valueOf(0), ArbitraryInstances.get(Double.class));
161     assertEquals(UnsignedInteger.ZERO, ArbitraryInstances.get(UnsignedInteger.class));
162     assertEquals(UnsignedLong.ZERO, ArbitraryInstances.get(UnsignedLong.class));
163     assertEquals(0, ArbitraryInstances.get(BigDecimal.class).intValue());
164     assertEquals(0, ArbitraryInstances.get(BigInteger.class).intValue());
165     assertEquals("", ArbitraryInstances.get(String.class));
166     assertEquals("", ArbitraryInstances.get(CharSequence.class));
167     assertEquals(TimeUnit.SECONDS, ArbitraryInstances.get(TimeUnit.class));
168     assertNotNull(ArbitraryInstances.get(Object.class));
169     assertEquals(0, ArbitraryInstances.get(Number.class));
170     assertEquals(Charsets.UTF_8, ArbitraryInstances.get(Charset.class));
171     assertEquals(Optional.empty(), ArbitraryInstances.get(Optional.class));
172     assertEquals(OptionalInt.empty(), ArbitraryInstances.get(OptionalInt.class));
173     assertEquals(OptionalLong.empty(), ArbitraryInstances.get(OptionalLong.class));
174     assertEquals(OptionalDouble.empty(), ArbitraryInstances.get(OptionalDouble.class));
175     assertNotNull(ArbitraryInstances.get(UUID.class));
176   }
177 
testGet_collections()178   public void testGet_collections() {
179     assertEquals(ImmutableSet.of().iterator(), ArbitraryInstances.get(Iterator.class));
180     assertFalse(ArbitraryInstances.get(PeekingIterator.class).hasNext());
181     assertFalse(ArbitraryInstances.get(ListIterator.class).hasNext());
182     assertEquals(ImmutableSet.of(), ArbitraryInstances.get(Iterable.class));
183     assertEquals(ImmutableSet.of(), ArbitraryInstances.get(Set.class));
184     assertEquals(ImmutableSet.of(), ArbitraryInstances.get(ImmutableSet.class));
185     assertEquals(ImmutableSortedSet.of(), ArbitraryInstances.get(SortedSet.class));
186     assertEquals(ImmutableSortedSet.of(), ArbitraryInstances.get(ImmutableSortedSet.class));
187     assertEquals(ImmutableList.of(), ArbitraryInstances.get(Collection.class));
188     assertEquals(ImmutableList.of(), ArbitraryInstances.get(ImmutableCollection.class));
189     assertEquals(ImmutableList.of(), ArbitraryInstances.get(List.class));
190     assertEquals(ImmutableList.of(), ArbitraryInstances.get(ImmutableList.class));
191     assertEquals(ImmutableMap.of(), ArbitraryInstances.get(Map.class));
192     assertEquals(ImmutableMap.of(), ArbitraryInstances.get(ImmutableMap.class));
193     assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(SortedMap.class));
194     assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(ImmutableSortedMap.class));
195     assertEquals(ImmutableMultiset.of(), ArbitraryInstances.get(Multiset.class));
196     assertEquals(ImmutableMultiset.of(), ArbitraryInstances.get(ImmutableMultiset.class));
197     assertTrue(ArbitraryInstances.get(SortedMultiset.class).isEmpty());
198     assertEquals(ImmutableMultimap.of(), ArbitraryInstances.get(Multimap.class));
199     assertEquals(ImmutableMultimap.of(), ArbitraryInstances.get(ImmutableMultimap.class));
200     assertTrue(ArbitraryInstances.get(SortedSetMultimap.class).isEmpty());
201     assertEquals(ImmutableTable.of(), ArbitraryInstances.get(Table.class));
202     assertEquals(ImmutableTable.of(), ArbitraryInstances.get(ImmutableTable.class));
203     assertTrue(ArbitraryInstances.get(RowSortedTable.class).isEmpty());
204     assertEquals(ImmutableBiMap.of(), ArbitraryInstances.get(BiMap.class));
205     assertEquals(ImmutableBiMap.of(), ArbitraryInstances.get(ImmutableBiMap.class));
206     assertTrue(ArbitraryInstances.get(ImmutableClassToInstanceMap.class).isEmpty());
207     assertTrue(ArbitraryInstances.get(ClassToInstanceMap.class).isEmpty());
208     assertTrue(ArbitraryInstances.get(ListMultimap.class).isEmpty());
209     assertTrue(ArbitraryInstances.get(ImmutableListMultimap.class).isEmpty());
210     assertTrue(ArbitraryInstances.get(SetMultimap.class).isEmpty());
211     assertTrue(ArbitraryInstances.get(ImmutableSetMultimap.class).isEmpty());
212     assertTrue(ArbitraryInstances.get(MapDifference.class).areEqual());
213     assertTrue(ArbitraryInstances.get(SortedMapDifference.class).areEqual());
214     assertEquals(Range.all(), ArbitraryInstances.get(Range.class));
215     assertTrue(ArbitraryInstances.get(NavigableSet.class).isEmpty());
216     assertTrue(ArbitraryInstances.get(NavigableMap.class).isEmpty());
217     assertTrue(ArbitraryInstances.get(LinkedList.class).isEmpty());
218     assertTrue(ArbitraryInstances.get(Deque.class).isEmpty());
219     assertTrue(ArbitraryInstances.get(Queue.class).isEmpty());
220     assertTrue(ArbitraryInstances.get(PriorityQueue.class).isEmpty());
221     assertTrue(ArbitraryInstances.get(BitSet.class).isEmpty());
222     assertTrue(ArbitraryInstances.get(TreeSet.class).isEmpty());
223     assertTrue(ArbitraryInstances.get(TreeMap.class).isEmpty());
224     assertFreshInstanceReturned(
225         LinkedList.class,
226         Deque.class,
227         Queue.class,
228         PriorityQueue.class,
229         BitSet.class,
230         TreeSet.class,
231         TreeMap.class);
232   }
233 
testGet_misc()234   public void testGet_misc() {
235     assertNotNull(ArbitraryInstances.get(CharMatcher.class));
236     assertNotNull(ArbitraryInstances.get(Currency.class).getCurrencyCode());
237     assertNotNull(ArbitraryInstances.get(Locale.class));
238     assertNotNull(ArbitraryInstances.get(Joiner.class).join(ImmutableList.of("a")));
239     assertNotNull(ArbitraryInstances.get(Splitter.class).split("a,b"));
240     assertThat(ArbitraryInstances.get(com.google.common.base.Optional.class)).isAbsent();
241     ArbitraryInstances.get(Stopwatch.class).start();
242     assertNotNull(ArbitraryInstances.get(Ticker.class));
243     assertFreshInstanceReturned(Random.class);
244     assertEquals(
245         ArbitraryInstances.get(Random.class).nextInt(),
246         ArbitraryInstances.get(Random.class).nextInt());
247   }
248 
testGet_concurrent()249   public void testGet_concurrent() {
250     assertTrue(ArbitraryInstances.get(BlockingDeque.class).isEmpty());
251     assertTrue(ArbitraryInstances.get(BlockingQueue.class).isEmpty());
252     assertTrue(ArbitraryInstances.get(DelayQueue.class).isEmpty());
253     assertTrue(ArbitraryInstances.get(SynchronousQueue.class).isEmpty());
254     assertTrue(ArbitraryInstances.get(PriorityBlockingQueue.class).isEmpty());
255     assertTrue(ArbitraryInstances.get(ConcurrentMap.class).isEmpty());
256     assertTrue(ArbitraryInstances.get(ConcurrentNavigableMap.class).isEmpty());
257     ArbitraryInstances.get(Executor.class).execute(ArbitraryInstances.get(Runnable.class));
258     assertNotNull(ArbitraryInstances.get(ThreadFactory.class));
259     assertFreshInstanceReturned(
260         BlockingQueue.class,
261         BlockingDeque.class,
262         PriorityBlockingQueue.class,
263         DelayQueue.class,
264         SynchronousQueue.class,
265         ConcurrentMap.class,
266         ConcurrentNavigableMap.class,
267         AtomicReference.class,
268         AtomicBoolean.class,
269         AtomicInteger.class,
270         AtomicLong.class,
271         AtomicDouble.class);
272   }
273 
274   @SuppressWarnings("unchecked") // functor classes have no type parameters
testGet_functors()275   public void testGet_functors() {
276     assertEquals(0, ArbitraryInstances.get(Comparator.class).compare("abc", 123));
277     assertTrue(ArbitraryInstances.get(Predicate.class).apply("abc"));
278     assertTrue(ArbitraryInstances.get(Equivalence.class).equivalent(1, 1));
279     assertFalse(ArbitraryInstances.get(Equivalence.class).equivalent(1, 2));
280   }
281 
282   @SuppressWarnings("SelfComparison")
testGet_comparable()283   public void testGet_comparable() {
284     @SuppressWarnings("unchecked") // The null value can compare with any Object
285     Comparable<Object> comparable = ArbitraryInstances.get(Comparable.class);
286     assertEquals(0, comparable.compareTo(comparable));
287     assertTrue(comparable.compareTo("") > 0);
288     try {
289       comparable.compareTo(null);
290       fail();
291     } catch (NullPointerException expected) {
292     }
293   }
294 
testGet_array()295   public void testGet_array() {
296     assertThat(ArbitraryInstances.get(int[].class)).isEmpty();
297     assertThat(ArbitraryInstances.get(Object[].class)).isEmpty();
298     assertThat(ArbitraryInstances.get(String[].class)).isEmpty();
299   }
300 
testGet_enum()301   public void testGet_enum() {
302     assertNull(ArbitraryInstances.get(EmptyEnum.class));
303     assertEquals(Direction.UP, ArbitraryInstances.get(Direction.class));
304   }
305 
testGet_interface()306   public void testGet_interface() {
307     assertNull(ArbitraryInstances.get(SomeInterface.class));
308   }
309 
testGet_runnable()310   public void testGet_runnable() {
311     ArbitraryInstances.get(Runnable.class).run();
312   }
313 
testGet_class()314   public void testGet_class() {
315     assertSame(SomeAbstractClass.INSTANCE, ArbitraryInstances.get(SomeAbstractClass.class));
316     assertSame(
317         WithPrivateConstructor.INSTANCE, ArbitraryInstances.get(WithPrivateConstructor.class));
318     assertNull(ArbitraryInstances.get(NoDefaultConstructor.class));
319     assertSame(
320         WithExceptionalConstructor.INSTANCE,
321         ArbitraryInstances.get(WithExceptionalConstructor.class));
322     assertNull(ArbitraryInstances.get(NonPublicClass.class));
323   }
324 
testGet_mutable()325   public void testGet_mutable() {
326     assertEquals(0, ArbitraryInstances.get(ArrayList.class).size());
327     assertEquals(0, ArbitraryInstances.get(HashMap.class).size());
328     assertThat(ArbitraryInstances.get(Appendable.class).toString()).isEmpty();
329     assertThat(ArbitraryInstances.get(StringBuilder.class).toString()).isEmpty();
330     assertThat(ArbitraryInstances.get(StringBuffer.class).toString()).isEmpty();
331     assertFreshInstanceReturned(
332         ArrayList.class,
333         HashMap.class,
334         Appendable.class,
335         StringBuilder.class,
336         StringBuffer.class,
337         Throwable.class,
338         Exception.class);
339   }
340 
testGet_io()341   public void testGet_io() throws IOException {
342     assertEquals(-1, ArbitraryInstances.get(InputStream.class).read());
343     assertEquals(-1, ArbitraryInstances.get(ByteArrayInputStream.class).read());
344     assertEquals(-1, ArbitraryInstances.get(Readable.class).read(CharBuffer.allocate(1)));
345     assertEquals(-1, ArbitraryInstances.get(Reader.class).read());
346     assertEquals(-1, ArbitraryInstances.get(StringReader.class).read());
347     assertEquals(0, ArbitraryInstances.get(Buffer.class).capacity());
348     assertEquals(0, ArbitraryInstances.get(CharBuffer.class).capacity());
349     assertEquals(0, ArbitraryInstances.get(ByteBuffer.class).capacity());
350     assertEquals(0, ArbitraryInstances.get(ShortBuffer.class).capacity());
351     assertEquals(0, ArbitraryInstances.get(IntBuffer.class).capacity());
352     assertEquals(0, ArbitraryInstances.get(LongBuffer.class).capacity());
353     assertEquals(0, ArbitraryInstances.get(FloatBuffer.class).capacity());
354     assertEquals(0, ArbitraryInstances.get(DoubleBuffer.class).capacity());
355     ArbitraryInstances.get(PrintStream.class).println("test");
356     ArbitraryInstances.get(PrintWriter.class).println("test");
357     assertNotNull(ArbitraryInstances.get(File.class));
358     assertFreshInstanceReturned(
359         ByteArrayOutputStream.class, OutputStream.class,
360         Writer.class, StringWriter.class,
361         PrintStream.class, PrintWriter.class);
362     assertEquals(ByteSource.empty(), ArbitraryInstances.get(ByteSource.class));
363     assertEquals(CharSource.empty(), ArbitraryInstances.get(CharSource.class));
364     assertNotNull(ArbitraryInstances.get(ByteSink.class));
365     assertNotNull(ArbitraryInstances.get(CharSink.class));
366   }
367 
testGet_reflect()368   public void testGet_reflect() {
369     assertNotNull(ArbitraryInstances.get(Type.class));
370     assertNotNull(ArbitraryInstances.get(AnnotatedElement.class));
371     assertNotNull(ArbitraryInstances.get(GenericDeclaration.class));
372   }
373 
testGet_regex()374   public void testGet_regex() {
375     assertEquals(Pattern.compile("").pattern(), ArbitraryInstances.get(Pattern.class).pattern());
376     assertEquals(0, ArbitraryInstances.get(MatchResult.class).groupCount());
377   }
378 
testGet_usePublicConstant()379   public void testGet_usePublicConstant() {
380     assertSame(WithPublicConstant.INSTANCE, ArbitraryInstances.get(WithPublicConstant.class));
381   }
382 
testGet_useFirstPublicConstant()383   public void testGet_useFirstPublicConstant() {
384     assertSame(WithPublicConstants.FIRST, ArbitraryInstances.get(WithPublicConstants.class));
385   }
386 
testGet_nullConstantIgnored()387   public void testGet_nullConstantIgnored() {
388     assertSame(FirstConstantIsNull.SECOND, ArbitraryInstances.get(FirstConstantIsNull.class));
389   }
390 
testGet_constantWithGenericsNotUsed()391   public void testGet_constantWithGenericsNotUsed() {
392     assertNull(ArbitraryInstances.get(WithGenericConstant.class));
393   }
394 
testGet_nullConstant()395   public void testGet_nullConstant() {
396     assertNull(ArbitraryInstances.get(WithNullConstant.class));
397   }
398 
testGet_constantTypeDoesNotMatch()399   public void testGet_constantTypeDoesNotMatch() {
400     assertNull(ArbitraryInstances.get(ParentClassHasConstant.class));
401   }
402 
testGet_nonPublicConstantNotUsed()403   public void testGet_nonPublicConstantNotUsed() {
404     assertNull(ArbitraryInstances.get(NonPublicConstantIgnored.class));
405   }
406 
testGet_nonStaticFieldNotUsed()407   public void testGet_nonStaticFieldNotUsed() {
408     assertNull(ArbitraryInstances.get(NonStaticFieldIgnored.class));
409   }
410 
testGet_constructorPreferredOverConstants()411   public void testGet_constructorPreferredOverConstants() {
412     assertNotNull(ArbitraryInstances.get(WithPublicConstructorAndConstant.class));
413     assertTrue(
414         ArbitraryInstances.get(WithPublicConstructorAndConstant.class)
415             != ArbitraryInstances.get(WithPublicConstructorAndConstant.class));
416   }
417 
testGet_nonFinalFieldNotUsed()418   public void testGet_nonFinalFieldNotUsed() {
419     assertNull(ArbitraryInstances.get(NonFinalFieldIgnored.class));
420   }
421 
assertFreshInstanceReturned(Class<?>.... mutableClasses)422   private static void assertFreshInstanceReturned(Class<?>... mutableClasses) {
423     for (Class<?> mutableClass : mutableClasses) {
424       Object instance = ArbitraryInstances.get(mutableClass);
425       assertNotNull("Expected to return non-null for: " + mutableClass, instance);
426       assertNotSame(
427           "Expected to return fresh instance for: " + mutableClass,
428           instance,
429           ArbitraryInstances.get(mutableClass));
430     }
431   }
432 
433   private enum EmptyEnum {}
434 
435   private enum Direction {
436     UP,
437     DOWN
438   }
439 
440   public interface SomeInterface {}
441 
442   public abstract static class SomeAbstractClass {
443     public static final SomeAbstractClass INSTANCE = new SomeAbstractClass() {};
444 
SomeAbstractClass()445     public SomeAbstractClass() {}
446   }
447 
448   static class NonPublicClass {
NonPublicClass()449     public NonPublicClass() {}
450   }
451 
452   private static class WithPrivateConstructor {
453     public static final WithPrivateConstructor INSTANCE = new WithPrivateConstructor();
454   }
455 
456   public static class NoDefaultConstructor {
NoDefaultConstructor(@uppressWarnings"unused") int i)457     public NoDefaultConstructor(@SuppressWarnings("unused") int i) {}
458   }
459 
460   public static class WithExceptionalConstructor {
461     public static final WithExceptionalConstructor INSTANCE =
462         new WithExceptionalConstructor("whatever");
463 
WithExceptionalConstructor()464     public WithExceptionalConstructor() {
465       throw new RuntimeException();
466     }
467 
WithExceptionalConstructor(String unused)468     private WithExceptionalConstructor(String unused) {}
469   }
470 
471   private static class WithPublicConstant {
472     public static final WithPublicConstant INSTANCE = new WithPublicConstant();
473   }
474 
475   private static class ParentClassHasConstant extends WithPublicConstant {}
476 
477   public static class WithGenericConstant<T> {
478     public static final WithGenericConstant<String> STRING_CONSTANT = new WithGenericConstant<>();
479 
WithGenericConstant()480     private WithGenericConstant() {}
481   }
482 
483   public static class WithNullConstant {
484     public static final WithNullConstant NULL = null;
485 
WithNullConstant()486     private WithNullConstant() {}
487   }
488 
489   public static class WithPublicConstructorAndConstant {
490     public static final WithPublicConstructorAndConstant INSTANCE =
491         new WithPublicConstructorAndConstant();
492 
WithPublicConstructorAndConstant()493     public WithPublicConstructorAndConstant() {}
494   }
495 
496   private static class WithPublicConstants {
497     public static final WithPublicConstants FIRST = new WithPublicConstants();
498 
499     // To test that we pick the first constant alphabetically
500     @SuppressWarnings("unused")
501     public static final WithPublicConstants SECOND = new WithPublicConstants();
502   }
503 
504   private static class FirstConstantIsNull {
505     // To test that null constant is ignored
506     @SuppressWarnings("unused")
507     public static final FirstConstantIsNull FIRST = null;
508 
509     public static final FirstConstantIsNull SECOND = new FirstConstantIsNull();
510   }
511 
512   public static class NonFinalFieldIgnored {
513     public static NonFinalFieldIgnored instance = new NonFinalFieldIgnored();
514 
NonFinalFieldIgnored()515     private NonFinalFieldIgnored() {}
516   }
517 
518   public static class NonPublicConstantIgnored {
519     static final NonPublicConstantIgnored INSTANCE = new NonPublicConstantIgnored();
520 
NonPublicConstantIgnored()521     private NonPublicConstantIgnored() {}
522   }
523 
524   public static class NonStaticFieldIgnored {
525     // This should cause infinite recursion. But it shouldn't be used anyway.
526     public final NonStaticFieldIgnored instance = new NonStaticFieldIgnored();
527 
NonStaticFieldIgnored()528     private NonStaticFieldIgnored() {}
529   }
530 }
531