Implicitly constrain barback to versions pub supports.

sdk/lib/_internal/pub/test/version_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 version_test;
 
 import 'package:unittest/unittest.dart';
 import 'test_pub.dart';
 import '../lib/src/version.dart';
 
 main() {
   initConfig();
 
+  final v114 = new Version.parse('1.1.4');
   final v123 = new Version.parse('1.2.3');
-  final v114 = new Version.parse('1.1.4');
   final v124 = new Version.parse('1.2.4');
+  final v130 = new Version.parse('1.3.0');
+  final v140 = new Version.parse('1.4.0');
   final v200 = new Version.parse('2.0.0');
+  final v201 = new Version.parse('2.0.1');
   final v234 = new Version.parse('2.3.4');
   final v250 = new Version.parse('2.5.0');
   final v300 = new Version.parse('3.0.0');
 
   group('Version', () {
     test('none', () {
       expect(Version.none.toString(), equals('0.0.0'));
     });
 
     group('constructor', () {
@@ skipping 83 matching lines @@
 
       // Intersecting a range allows no versions if the range doesn't allow it.
       expect(v114.intersect(new VersionRange(min: v123, max: v124)).isEmpty,
           isTrue);
     });
 
     test('isEmpty', () {
       expect(v123.isEmpty, isFalse);
     });
 
+    test('nextMajor', () {
+      expect(v123.nextMajor, equals(v200));
+      expect(v114.nextMajor, equals(v200));
+      expect(v200.nextMajor, equals(v300));
+
+      // Ignores pre-release if not on a major version.
+      expect(new Version.parse('1.2.3-dev').nextMajor, equals(v200));
+
+      // Just removes it if on a major version.
+      expect(new Version.parse('2.0.0-dev').nextMajor, equals(v200));
+
+      // Strips build suffix.
+      expect(new Version.parse('1.2.3+patch').nextMajor, equals(v200));
+    });
+
+    test('nextMinor', () {
+      expect(v123.nextMinor, equals(v130));
+      expect(v130.nextMinor, equals(v140));
+
+      // Ignores pre-release if not on a minor version.
+      expect(new Version.parse('1.2.3-dev').nextMinor, equals(v130));
+
+      // Just removes it if on a minor version.
+      expect(new Version.parse('1.3.0-dev').nextMinor, equals(v130));
+
+      // Strips build suffix.
+      expect(new Version.parse('1.2.3+patch').nextMinor, equals(v130));
+    });
+
+    test('nextPatch', () {
+      expect(v123.nextPatch, equals(v124));
+      expect(v200.nextPatch, equals(v201));
+
+      // Just removes pre-release version if present.
+      expect(new Version.parse('1.2.4-dev').nextPatch, equals(v124));
+
+      // Strips build suffix.
+      expect(new Version.parse('1.2.3+patch').nextPatch, equals(v124));
+    });
+
     test('parse()', () {
       expect(new Version.parse('0.0.0'), equals(new Version(0, 0, 0)));
       expect(new Version.parse('12.34.56'), equals(new Version(12, 34, 56)));
 
       expect(new Version.parse('1.2.3-alpha.1'), equals(
           new Version(1, 2, 3, pre: 'alpha.1')));
       expect(new Version.parse('1.2.3-x.7.z-92'), equals(
           new Version(1, 2, 3, pre: 'x.7.z-92')));
 
       expect(new Version.parse('1.2.3+build.1'), equals(
@@ skipping 345 matching lines @@
 
 Matcher allows(List<Version> versions) =>
     new VersionConstraintMatcher(versions, true);
 
 Matcher doesNotAllow(List<Version> versions) =>
     new VersionConstraintMatcher(versions, false);
 
 throwsIllegalArg(function) {
   expect(function, throwsA((e) => e is ArgumentError));
 }