Added a new matcher for pairwise comparison of iterables with a custom comparator.

pkg/unittest/test/matchers_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library unittestTests;
 import 'package:unittest/unittest.dart';
 import 'dart:async';
 import 'dart:collection';
 part 'test_utils.dart';
 
@@ skipping 505 matching lines @@
       shouldFail(d, unorderedEquals([1]),
           "Expected: equals <[1]> unordered "
           "but: has too many elements (2 > 1).");
       shouldFail(d, unorderedEquals([3, 2, 1]),
           "Expected: equals <[3, 2, 1]> unordered "
           "but: has too few elements (2 < 3).");
       shouldFail(d, unorderedEquals([3, 1]),
           "Expected: equals <[3, 1]> unordered "
           "but: has no match for element <3> at position 0.");
     });
+
+    test('pairwise compare', () {
+      var c = [1, 2];
+      var d = [1, 2, 3];
+      var e = [1, 4, 9];
+      shouldFail('x', pairwiseCompare(e, (e,a) => a <= e,
+          "less than or equal"),
+          "Expected: pairwise less than or equal <[1, 4, 9]> but: "
+          "not an Iterable.");
+      shouldFail(c, pairwiseCompare(e, (e,a) => a <= e, "less than or equal"),
+          "Expected: pairwise less than or equal <[1, 4, 9]> but: "
+          "length was 2 instead of 3.");
+      shouldPass(d, pairwiseCompare(e, (e,a) => a <= e, "less than or equal"));
+      shouldFail(d, pairwiseCompare(e, (e,a) => a < e, "less than"),
+          "Expected: pairwise less than <[1, 4, 9]> but: "
+          "<1> not less than <1> at position 0.");
+      shouldPass(d, pairwiseCompare(e, (e,a) => a * a == e, "square root of"));
+      shouldFail(d, pairwiseCompare(e, (e,a) => a + a == e, "double"),
+          "Expected: pairwise double <[1, 4, 9]> but: "
+          "<1> not double <1> at position 0.");
+    });
   });
 
   group('Map Matchers', () {
 
     test('isEmpty', () {
       var a = new Map();
       shouldPass({}, isEmpty);
       shouldPass(a, isEmpty);
       a['foo'] = 'bar';
       shouldFail(a, isEmpty, "Expected: empty but: was <{foo: bar}>.");
@@ skipping 173 matching lines @@
       w.price = 10;
       shouldPass(w, new HasPrice(10));
       shouldPass(w, new HasPrice(greaterThan(0)));
       shouldFail(w, new HasPrice(greaterThan(10)),
           'Expected: Widget with a price that is a value greater than <10> '
           'but: price was <10>.');
     });
   });
 }