Don't use LinkedHashSet in SubjectUtil.countDuplicates() in case the …

…elements

don't implement hashCode() (e.g., ProtoBuf's MessageSet!)

See []where the user can't use .containsExactlyElementsIn().

This at least partially addresses #176
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=89605122

core/src/main/java/com/google/common/truth/SubjectUtils.java

@@ -19,9 +19,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.LinkedHashSet;
 import java.util.List;
-import java.util.Set;
 
 /**
  * Utility methods used in Subject<T> implementors.
@@ -71,7 +69,14 @@ static <T> int countOf(T t, Iterable<T> items) {
   }
 
   static <T> List<Object> countDuplicates(Collection<T> items) {
-    Set<T> itemSet = new LinkedHashSet<T>(items);
+    // We use a List to de-dupe instead of a Set in case the elements don't have a proper
+    // .hashCode() method (e.g., MessageSet from old versions of protobuf).
+    List<T> itemSet = new ArrayList<T>();
+    for (T item : items) {
+      if (!itemSet.contains(item)) {
+        itemSet.add(item);
+      }
+    }
     Object[] params = new Object[itemSet.size()];
     int n = 0;
     for (T item : itemSet) {

core/src/test/java/com/google/common/truth/IterableTest.java

@@ -407,6 +407,38 @@ public class IterableTest {
     assertThat(iterable(1, null, 3)).containsExactly(1, 3, (Integer) null);
   }
 
+  @Test public void iterableContainsExactlyWithElementsThatThrowWhenYouCallHashCode() {
+    HashCodeThrower one = new HashCodeThrower();
+    HashCodeThrower two = new HashCodeThrower();
+
+    assertThat(iterable(one, two)).containsExactly(two, one);
+    assertThat(iterable(one, two)).containsExactly(one, two).inOrder();
+    assertThat(iterable(one, two)).containsExactlyElementsIn(iterable(two, one));
+    assertThat(iterable(one, two)).containsExactlyElementsIn(iterable(one, two)).inOrder();
+
+    try {
+      assertThat(iterable(one, two)).containsExactly(one);
+    } catch (AssertionError expected) {
+      assertThat(expected).hasMessage(
+          "Not true that <[HCT, HCT]> contains exactly <[HCT]>. "
+          + "It has unexpected items <[HCT]>");
+      return;
+    }
+    fail();
+  }
+
+  private static class HashCodeThrower {
+    @Override public boolean equals(Object other) {
+      return this == other;
+    }
+    @Override public int hashCode() {
+      throw new UnsupportedOperationException();
+    }
+    @Override public String toString() {
+      return "HCT";
+    }
+  }
+
   @Test public void iterableContainsExactlyElementsInErrorMessageIsOrdered() {
     try {
       assertThat(asList("foo OR bar")).containsExactlyElementsIn(asList("foo", "bar"));