If two Maps are compared with an equals() matcher and they have the same length,

pkg/unittest/test/matchers_test.dart

Index: pkg/unittest/test/matchers_test.dart
===================================================================
--- pkg/unittest/test/matchers_test.dart	(revision 18269)
+++ pkg/unittest/test/matchers_test.dart	(working copy)
@@ -521,6 +521,18 @@
       shouldFail(a, isEmpty, "Expected: empty but: was <{foo: bar}>.");
     });
 
+    test('equals', () {
+      var a = new Map();
+      a['foo'] = 'bar';
+      var b = new Map();
+      b['foo'] = 'bar';
+      var c = new Map();
+      c['bar'] = 'foo';
+      shouldPass(a, equals(b));
+      shouldFail(b, equals(c),
+          "Expected: <{bar: foo}> but: missing map key bar 'bar'.");
+    });
+
     test('contains', () {
       var a = new Map();
       a['foo'] = 'bar';