Use System.identityHashCode() to disambiguate objects with same hash …

…code (fixes #45)

This commit also modifies the way the class name is printed: for
anonymous classes, the whole name is printed (since
Class.getSimpleName() returns an empty string).

src/main/java/org/assertj/core/presentation/Representation.java

@@ -44,7 +44,7 @@
 public interface Representation {
 
   /**
-   * Returns the {@code String} representation of the given object. It may or not the object's own implementation of
+   * Returns the {@code String} representation of the given object. It may or may not be the object's own implementation of
    * {@code toString}.
    *
    * @param object the object to represent.
@@ -53,11 +53,11 @@ public interface Representation {
   String toStringOf(Object object);
 
   /**
-   * Returns the {@code String} representation of the given object with its type and hexadecimal hash code so that 
-   * it can be differentied from other objects with the same {@link #toStringOf(Object)} representation.
+   * Returns the {@code String} representation of the given object with its type and hexadecimal identity hash code so that
+   * it can be differentiated from other objects with the same {@link #toStringOf(Object)} representation.
    *
    * @param object the object to represent.
-   * @return the {@code toString} representation of the given object.
+   * @return the unambiguous {@code toString} representation of the given object.
    */
   String unambiguousToStringOf(Object object);
 

src/main/java/org/assertj/core/presentation/StandardRepresentation.java

@@ -199,7 +199,10 @@ protected boolean hasCustomFormatterFor(Object object) {
   @Override
   public String unambiguousToStringOf(Object obj) {
     return obj == null ? null
-        : String.format("%s (%s@%s)", toStringOf(obj), obj.getClass().getSimpleName(), toHexString(obj.hashCode()));
+        : String.format("%s (%s@%s)",
+                        toStringOf(obj),
+                        obj.getClass().isAnonymousClass() ? obj.getClass().getName() : obj.getClass().getSimpleName(),
+                        toHexString(System.identityHashCode(obj)));
   }
 
   /**

src/test/java/org/assertj/core/error/ShouldBeEqualByComparingFieldByFieldRecursively_create_Test.java

@@ -66,8 +66,8 @@ public void should_use_unambiguous_fields_description_when_standard_description_
     List<Difference> differences = determineDifferences(withHashSet, withSortedSet, null, null);
     // WHEN
     // @format:off
-    String message = shouldBeEqualByComparingFieldByFieldRecursive(withSortedSet,
-                                                                   withHashSet,
+    String message = shouldBeEqualByComparingFieldByFieldRecursive(withHashSet,
+                                                                   withSortedSet,
                                                                    differences,
                                                                    REPRESENTATION)
         .create(new TextDescription("Test"), REPRESENTATION);
@@ -83,8 +83,8 @@ public void should_use_unambiguous_fields_description_when_standard_description_
                                          "Path to difference: <collection>%n" +
                                          "- actual  : <[\"bar\", \"foo\"] (LinkedHashSet@%s)>%n" +
                                          "- expected: <[\"bar\", \"foo\"] (TreeSet@%s)>",
-                                         toHexString(withSortedSet.collection.hashCode()),
-                                         toHexString(withHashSet.collection.hashCode())));
+                                         toHexString(System.identityHashCode(withHashSet.collection)),
+                                         toHexString(System.identityHashCode(withSortedSet.collection))));
   }
 
   @Test
@@ -98,8 +98,8 @@ public void should_use_unambiguous_fields_description_when_standard_description_
     List<Difference> differences = determineDifferences(withLinkedHashMap, withTreeMap, null, null);
     // WHEN
     // @format:off
-    String message = shouldBeEqualByComparingFieldByFieldRecursive(withTreeMap,
-                                                                   withLinkedHashMap,
+    String message = shouldBeEqualByComparingFieldByFieldRecursive(withLinkedHashMap,
+                                                                   withTreeMap,
                                                                    differences,
                                                                    REPRESENTATION)
                                                           .create(new TextDescription("Test"), REPRESENTATION);
@@ -115,8 +115,8 @@ public void should_use_unambiguous_fields_description_when_standard_description_
                                          "Path to difference: <map>%n" +
                                          "- actual  : <{1L=true, 2L=false} (LinkedHashMap@%s)>%n" +
                                          "- expected: <{1L=true, 2L=false} (TreeMap@%s)>",
-                                         toHexString(withTreeMap.map.hashCode()),
-                                         toHexString(withLinkedHashMap.map.hashCode())));
+                                         toHexString(System.identityHashCode(withLinkedHashMap.map)),
+                                         toHexString(System.identityHashCode(withTreeMap.map))));
   }
 
   @Test
@@ -152,6 +152,7 @@ public void should_precise_missing_fields_when_actual_does_not_declare_all_expec
                                          personHash, personDAOHash));
   }
 
+  @Test
   public void should_not_fall_with_npe_if_field_of_one_of_compared_objects_is_null() {
     final Name actualName = new Name("Andy");
     final Name nullName = new Name(null);