robust implementation of the appendValue method in BaseDescription that does sensible things in the face of an object whose toString method throws an exception. This is in response to issue 184 (on the google code issue tracker).

scarytom · scarytom · commit 6d06cb384f25 · 2012-05-31T20:59:10.000+01:00
diff --git a/hamcrest-core/src/main/java/org/hamcrest/BaseDescription.java b/hamcrest-core/src/main/java/org/hamcrest/BaseDescription.java
@@ -37,26 +37,35 @@ public Description appendValue(Object value) {
             append('"');
         } else if (value instanceof Short) {
             append('<');
-            append(valueOf(value));
+            append(descriptionOf(value));
             append("s>");
         } else if (value instanceof Long) {
             append('<');
-            append(valueOf(value));
+            append(descriptionOf(value));
             append("L>");
         } else if (value instanceof Float) {
             append('<');
-            append(valueOf(value));
+            append(descriptionOf(value));
             append("F>");
         } else if (value.getClass().isArray()) {
             appendValueList("[",", ","]", new ArrayIterator(value));
         } else {
             append('<');
-            append(valueOf(value));
+            append(descriptionOf(value));
             append('>');
         }
         return this;
     }
-    
+
+    private String descriptionOf(Object value) {
+        try {
+            return valueOf(value);
+        }
+        catch (Exception e) {
+            return value.getClass().getName() + "@" + Integer.toHexString(value.hashCode());
+        }
+    }
+
     @Override
     public <T> Description appendValueList(String start, String separator, String end, T... values) {
         return appendValueList(start, separator, end, Arrays.asList(values));
diff --git a/hamcrest-unit-test/src/main/java/org/hamcrest/BaseDescriptionTest.java b/hamcrest-unit-test/src/main/java/org/hamcrest/BaseDescriptionTest.java
@@ -52,4 +52,16 @@ public void testBracketsAppendedObjectValue() {
         baseDescription.appendValue(value);
         assertEquals("<" + value.toString() + ">", result.toString());
     }
+    
+    public void testSafelyDescribesAppendedValueOfObjectWhoseToStringThrowsAnException() {
+        final Object value = new Object() {
+            @Override public String toString() {
+                throw new UnsupportedOperationException();
+            }
+        };
+        
+        final String expected = value.getClass().getName() + "@" + Integer.toHexString(value.hashCode());
+        baseDescription.appendValue(value);
+        assertEquals("<" + expected + ">", result.toString());
+    }
 }
