Add pretty-printing to unittest and more thoroughly print values.

pkg/unittest/lib/src/description.dart

Index: pkg/unittest/lib/src/description.dart
diff --git a/pkg/unittest/lib/src/description.dart b/pkg/unittest/lib/src/description.dart
index cdd819348914e70c4434350c48a5c296385d1951..cde5243ef175f7731ee5c025243182e4d6a07262 100644
--- a/pkg/unittest/lib/src/description.dart
+++ b/pkg/unittest/lib/src/description.dart
@@ -41,23 +41,8 @@ class StringDescription implements Description {
   Description addDescriptionOf(value) {
     if (value is Matcher) {
       value.describe(this);
-    } else if (value is String) {
-      _addEscapedString(value);
     } else {
-      String description = (value == null) ? "null" : value.toString();
-      if (description.startsWith('<') && description.endsWith('>')) {
-          add(description);
-      } else if (description.startsWith("Instance of")) {
-        add('<');
-        add(description);
-        add(':');
-        add(value.hashCode.toString());
-        add('>');
-      } else {
-        add('<');
-        add(description);
-        add('>');
-      }
+      add(prettyPrint(value, maxLineLength: 80, maxItems: 25));
     }
     return this;
   }
@@ -85,23 +70,7 @@ class StringDescription implements Description {
   /** Escape the control characters in [string] so that they are visible. */
   _addEscapedString(String string) {
     add("'");
-    for (var i = 0; i < string.length; i++) {
-      add(_escape(string[i]));
-    }
+    add(escapeString(string));
     add("'");
   }
-
-  /** Return the escaped form of a character [ch]. */
-  _escape(ch) {
-    if (ch == "'")
-      return "\'";
-    else if (ch == '\n')
-      return '\\n';
-    else if (ch == '\r')
-      return '\\r';
-    else if (ch == '\t')
-      return '\\t';
-    else
-      return ch;
-  }
 }