Harvest from pub. Mostly a straight copy, except:

test/version_constraint_test.dart

+// Copyright (c) 2014, 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 pub_semver.test.version_constraint_test;
+
+import 'package:unittest/unittest.dart';
+
+import 'package:pub_semver/pub_semver.dart';
+
+import 'utils.dart';
+
+main() {
+  test('any', () {
+    expect(VersionConstraint.any.isAny, isTrue);
+    expect(VersionConstraint.any, allows(
+        new Version.parse('0.0.0-blah'),
+        new Version.parse('1.2.3'),
+        new Version.parse('12345.678.90')));
+  });
+
+  test('empty', () {
+    expect(VersionConstraint.empty.isEmpty, isTrue);
+    expect(VersionConstraint.empty.isAny, isFalse);
+    expect(VersionConstraint.empty, doesNotAllow(
+        new Version.parse('0.0.0-blah'),
+        new Version.parse('1.2.3'),
+        new Version.parse('12345.678.90')));
+  });
+
+  group('parse()', () {
+    test('parses an exact version', () {
+      var constraint = new VersionConstraint.parse('1.2.3-alpha');
+
+      expect(constraint is Version, isTrue);
+      expect(constraint, equals(new Version(1, 2, 3, pre: 'alpha')));
+    });
+
+    test('parses "any"', () {
+      var constraint = new VersionConstraint.parse('any');
+
+      expect(constraint is VersionConstraint, isTrue);
+      expect(constraint, allows(
+          new Version.parse('0.0.0'),
+          new Version.parse('1.2.3'),
+          new Version.parse('12345.678.90')));
+    });
+
+    test('parses a ">" minimum version', () {
+      var constraint = new VersionConstraint.parse('>1.2.3');
+
+      expect(constraint, allows(
+          new Version.parse('1.2.3+foo'),
+          new Version.parse('1.2.4')));
+      expect(constraint, doesNotAllow(
+          new Version.parse('1.2.1'),
+          new Version.parse('1.2.3-build'),
+          new Version.parse('1.2.3')));
+    });
+
+    test('parses a ">=" minimum version', () {
+      var constraint = new VersionConstraint.parse('>=1.2.3');
+
+      expect(constraint, allows(
+          new Version.parse('1.2.3'),
+          new Version.parse('1.2.3+foo'),
+          new Version.parse('1.2.4')));
+      expect(constraint, doesNotAllow(
+          new Version.parse('1.2.1'),
+          new Version.parse('1.2.3-build')));
+    });
+
+    test('parses a "<" maximum version', () {
+      var constraint = new VersionConstraint.parse('<1.2.3');
+
+      expect(constraint, allows(
+          new Version.parse('1.2.1'),
+          new Version.parse('1.2.2+foo')));
+      expect(constraint, doesNotAllow(
+          new Version.parse('1.2.3'),
+          new Version.parse('1.2.3+foo'),
+          new Version.parse('1.2.4')));
+    });
+
+    test('parses a "<=" maximum version', () {
+      var constraint = new VersionConstraint.parse('<=1.2.3');
+
+      expect(constraint, allows(
+          new Version.parse('1.2.1'),
+          new Version.parse('1.2.3-build'),
+          new Version.parse('1.2.3')));
+      expect(constraint, doesNotAllow(
+          new Version.parse('1.2.3+foo'),
+          new Version.parse('1.2.4')));
+    });
+
+    test('parses a series of space-separated constraints', () {
+      var constraint = new VersionConstraint.parse('>1.0.0 >=1.2.3 <1.3.0');
+
+      expect(constraint, allows(
+          new Version.parse('1.2.3'),
+          new Version.parse('1.2.5')));
+      expect(constraint, doesNotAllow(
+          new Version.parse('1.2.3-pre'),
+          new Version.parse('1.3.0'),
+          new Version.parse('3.4.5')));
+    });
+
+    test('ignores whitespace around operators', () {
+      var constraint = new VersionConstraint.parse(' >1.0.0>=1.2.3 < 1.3.0');
+
+      expect(constraint, allows(
+          new Version.parse('1.2.3'),
+          new Version.parse('1.2.5')));
+      expect(constraint, doesNotAllow(
+          new Version.parse('1.2.3-pre'),
+          new Version.parse('1.3.0'),
+          new Version.parse('3.4.5')));
+    });
+
+    test('does not allow "any" to be mixed with other constraints', () {
+      expect(() => new VersionConstraint.parse('any 1.0.0'),
+          throwsFormatException);
+    });
+
+    test('throws FormatException on a bad string', () {
+      var bad = [
+         "", "   ",               // Empty string.
+         "foo",                   // Bad text.
+         ">foo",                  // Bad text after operator.
+         "1.0.0 foo", "1.0.0foo", // Bad text after version.
+         "anything",              // Bad text after "any".
+         "<>1.0.0",               // Multiple operators.
+         "1.0.0<"                 // Trailing operator.
+      ];
+
+      for (var text in bad) {
+        expect(() => new VersionConstraint.parse(text),
+            throwsFormatException);
+      }
+    });
+  });
+}