Improved error messages from unittest.

pkg/unittest/lib/src/numeric_matchers.dart

Index: pkg/unittest/lib/src/numeric_matchers.dart
===================================================================
--- pkg/unittest/lib/src/numeric_matchers.dart	(revision 24002)
+++ pkg/unittest/lib/src/numeric_matchers.dart	(working copy)
@@ -100,7 +100,7 @@
     [valueInDescription = true]) :
       this._valueInDescription = valueInDescription;
 
-  bool matches(item, MatchState matchState) {
+  bool matches(item, Map matchState) {
     if (item == _value) {
       return _equalValue;
     } else if (item < _value) {
@@ -118,6 +118,12 @@
       return description.add(_comparisonDescription);
     }
   }
+
+  Description describeMismatch(item, Description mismatchDescription,
+                               Map matchState, bool verbose) {
+    mismatchDescription.add('is not ');
+    return describe(mismatchDescription);
+  }
 }
 
 /**
@@ -132,7 +138,7 @@
 
   const _IsCloseTo(this._value, this._delta);
 
-  bool matches(item, MatchState matchState) {
+  bool matches(item, Map matchState) {
     if (!_isNumeric(item)) {
       return false;
     }
@@ -148,14 +154,14 @@
         addDescriptionOf(_value);
 
   Description describeMismatch(item, Description mismatchDescription,
-                               MatchState matchState, bool verbose) {
+                               Map matchState, bool verbose) {
     if (item is !num) {
       return mismatchDescription.add(' not numeric');
     } else {
       var diff = item - _value;
       if (diff < 0) diff = -diff;
       return mismatchDescription.
-          add(' differed by ').
+          add(' differs by ').
           addDescriptionOf(diff);
     }
   }
@@ -192,7 +198,7 @@
   const _InRange(this._low, this._high,
     this._lowMatchValue, this._highMatchValue);
 
-  bool matches(value, MatchState matchState) {
+  bool matches(value, Map matchState) {
     if (value is !num) {
       return false;
     }
@@ -214,7 +220,7 @@
         "$_high (${_highMatchValue ? 'inclusive' : 'exclusive'})");
 
   Description describeMismatch(item, Description mismatchDescription,
-                               MatchState matchState, bool verbose) {
+                               Map matchState, bool verbose) {
     if (item is !num) {
       return mismatchDescription.
           addDescriptionOf(item).