Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/version_solver_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 pub_upgrade_test;
-
-import 'dart:async';
-
-import 'package:pub_semver/pub_semver.dart';
-import 'package:unittest/unittest.dart';
-
-import '../lib/src/lock_file.dart';
-import '../lib/src/log.dart' as log;
-import '../lib/src/package.dart';
-import '../lib/src/pubspec.dart';
-import '../lib/src/sdk.dart' as sdk;
-import '../lib/src/source/cached.dart';
-import '../lib/src/system_cache.dart';
-import '../lib/src/utils.dart';
-import '../lib/src/solver/version_solver.dart';
-import 'test_pub.dart';
-
-MockSource source1;
-MockSource source2;
-
-main() {
-  initConfig();
-
-  // Uncomment this to debug failing tests.
-  // log.verbosity = log.Verbosity.SOLVER;
-
-  // Since this test isn't run from the SDK, it can't find the "version" file
-  // to load. Instead, just manually inject a version.
-  sdk.version = new Version(1, 2, 3);
-
-  group('basic graph', basicGraph);
-  group('with lockfile', withLockFile);
-  group('root dependency', rootDependency);
-  group('dev dependency', devDependency);
-  group('unsolvable', unsolvable);
-  group('bad source', badSource);
-  group('backtracking', backtracking);
-  group('SDK constraint', sdkConstraint);
-  group('pre-release', prerelease);
-  group('override', override);
-  group('downgrade', downgrade);
-}
-
-void basicGraph() {
-  testResolve('no dependencies', {
-    'myapp 0.0.0': {}
-  }, result: {
-    'myapp from root': '0.0.0'
-  });
-
-  testResolve('simple dependency tree', {
-    'myapp 0.0.0': {
-      'a': '1.0.0',
-      'b': '1.0.0'
-    },
-    'a 1.0.0': {
-      'aa': '1.0.0',
-      'ab': '1.0.0'
-    },
-    'aa 1.0.0': {},
-    'ab 1.0.0': {},
-    'b 1.0.0': {
-      'ba': '1.0.0',
-      'bb': '1.0.0'
-    },
-    'ba 1.0.0': {},
-    'bb 1.0.0': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0',
-    'aa': '1.0.0',
-    'ab': '1.0.0',
-    'b': '1.0.0',
-    'ba': '1.0.0',
-    'bb': '1.0.0'
-  });
-
-  testResolve('shared dependency with overlapping constraints', {
-    'myapp 0.0.0': {
-      'a': '1.0.0',
-      'b': '1.0.0'
-    },
-    'a 1.0.0': {
-      'shared': '>=2.0.0 <4.0.0'
-    },
-    'b 1.0.0': {
-      'shared': '>=3.0.0 <5.0.0'
-    },
-    'shared 2.0.0': {},
-    'shared 3.0.0': {},
-    'shared 3.6.9': {},
-    'shared 4.0.0': {},
-    'shared 5.0.0': {},
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0',
-    'b': '1.0.0',
-    'shared': '3.6.9'
-  });
-
-  testResolve('shared dependency where dependent version in turn affects '
-              'other dependencies', {
-    'myapp 0.0.0': {
-      'foo': '<=1.0.2',
-      'bar': '1.0.0'
-    },
-    'foo 1.0.0': {},
-    'foo 1.0.1': { 'bang': '1.0.0' },
-    'foo 1.0.2': { 'whoop': '1.0.0' },
-    'foo 1.0.3': { 'zoop': '1.0.0' },
-    'bar 1.0.0': { 'foo': '<=1.0.1' },
-    'bang 1.0.0': {},
-    'whoop 1.0.0': {},
-    'zoop 1.0.0': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '1.0.1',
-    'bar': '1.0.0',
-    'bang': '1.0.0'
-  }, maxTries: 2);
-
-  testResolve('circular dependency', {
-    'myapp 1.0.0': {
-      'foo': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'bar': '1.0.0'
-    },
-    'bar 1.0.0': {
-      'foo': '1.0.0'
-    }
-  }, result: {
-    'myapp from root': '1.0.0',
-    'foo': '1.0.0',
-    'bar': '1.0.0'
-  });
-
-  testResolve('removed dependency', {
-    'myapp 1.0.0': {
-      'foo': '1.0.0',
-      'bar': 'any'
-    },
-    'foo 1.0.0': {},
-    'foo 2.0.0': {},
-    'bar 1.0.0': {},
-    'bar 2.0.0': {
-      'baz': '1.0.0'
-    },
-    'baz 1.0.0': {
-      'foo': '2.0.0'
-    }
-  }, result: {
-    'myapp from root': '1.0.0',
-    'foo': '1.0.0',
-    'bar': '1.0.0'
-  }, maxTries: 2);
-}
-
-withLockFile() {
-  testResolve('with compatible locked dependency', {
-    'myapp 0.0.0': {
-      'foo': 'any'
-    },
-    'foo 1.0.0': { 'bar': '1.0.0' },
-    'foo 1.0.1': { 'bar': '1.0.1' },
-    'foo 1.0.2': { 'bar': '1.0.2' },
-    'bar 1.0.0': {},
-    'bar 1.0.1': {},
-    'bar 1.0.2': {}
-  }, lockfile: {
-    'foo': '1.0.1'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '1.0.1',
-    'bar': '1.0.1'
-  });
-
-  testResolve('with incompatible locked dependency', {
-    'myapp 0.0.0': {
-      'foo': '>1.0.1'
-    },
-    'foo 1.0.0': { 'bar': '1.0.0' },
-    'foo 1.0.1': { 'bar': '1.0.1' },
-    'foo 1.0.2': { 'bar': '1.0.2' },
-    'bar 1.0.0': {},
-    'bar 1.0.1': {},
-    'bar 1.0.2': {}
-  }, lockfile: {
-    'foo': '1.0.1'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '1.0.2',
-    'bar': '1.0.2'
-  });
-
-  testResolve('with unrelated locked dependency', {
-    'myapp 0.0.0': {
-      'foo': 'any'
-    },
-    'foo 1.0.0': { 'bar': '1.0.0' },
-    'foo 1.0.1': { 'bar': '1.0.1' },
-    'foo 1.0.2': { 'bar': '1.0.2' },
-    'bar 1.0.0': {},
-    'bar 1.0.1': {},
-    'bar 1.0.2': {},
-    'baz 1.0.0': {}
-  }, lockfile: {
-    'baz': '1.0.0'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '1.0.2',
-    'bar': '1.0.2'
-  });
-
-  testResolve('unlocks dependencies if necessary to ensure that a new '
-      'dependency is satisfied', {
-    'myapp 0.0.0': {
-      'foo': 'any',
-      'newdep': 'any'
-    },
-    'foo 1.0.0': { 'bar': '<2.0.0' },
-    'bar 1.0.0': { 'baz': '<2.0.0' },
-    'baz 1.0.0': { 'qux': '<2.0.0' },
-    'qux 1.0.0': {},
-    'foo 2.0.0': { 'bar': '<3.0.0' },
-    'bar 2.0.0': { 'baz': '<3.0.0' },
-    'baz 2.0.0': { 'qux': '<3.0.0' },
-    'qux 2.0.0': {},
-    'newdep 2.0.0': { 'baz': '>=1.5.0' }
-  }, lockfile: {
-    'foo': '1.0.0',
-    'bar': '1.0.0',
-    'baz': '1.0.0',
-    'qux': '1.0.0'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '2.0.0',
-    'bar': '2.0.0',
-    'baz': '2.0.0',
-    'qux': '1.0.0',
-    'newdep': '2.0.0'
-  }, maxTries: 4);
-}
-
-rootDependency() {
-  testResolve('with root source', {
-    'myapp 1.0.0': {
-      'foo': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'myapp from root': '>=1.0.0'
-    }
-  }, result: {
-    'myapp from root': '1.0.0',
-    'foo': '1.0.0'
-  });
-
-  testResolve('with different source', {
-    'myapp 1.0.0': {
-      'foo': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'myapp': '>=1.0.0'
-    }
-  }, result: {
-    'myapp from root': '1.0.0',
-    'foo': '1.0.0'
-  });
-
-  testResolve('with mismatched sources', {
-    'myapp 1.0.0': {
-      'foo': '1.0.0',
-      'bar': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'myapp': '>=1.0.0'
-    },
-    'bar 1.0.0': {
-      'myapp from mock2': '>=1.0.0'
-    }
-  }, error: sourceMismatch('myapp', 'foo', 'bar'));
-
-  testResolve('with wrong version', {
-    'myapp 1.0.0': {
-      'foo': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'myapp': '<1.0.0'
-    }
-  }, error: couldNotSolve);
-}
-
-devDependency() {
-  testResolve("includes root package's dev dependencies", {
-    'myapp 1.0.0': {
-      '(dev) foo': '1.0.0',
-      '(dev) bar': '1.0.0'
-    },
-    'foo 1.0.0': {},
-    'bar 1.0.0': {}
-  }, result: {
-    'myapp from root': '1.0.0',
-    'foo': '1.0.0',
-    'bar': '1.0.0'
-  });
-
-  testResolve("includes dev dependency's transitive dependencies", {
-    'myapp 1.0.0': {
-      '(dev) foo': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'bar': '1.0.0'
-    },
-    'bar 1.0.0': {}
-  }, result: {
-    'myapp from root': '1.0.0',
-    'foo': '1.0.0',
-    'bar': '1.0.0'
-  });
-
-  testResolve("ignores transitive dependency's dev dependencies", {
-    'myapp 1.0.0': {
-      'foo': '1.0.0'
-    },
-    'foo 1.0.0': {
-      '(dev) bar': '1.0.0'
-    },
-    'bar 1.0.0': {}
-  }, result: {
-    'myapp from root': '1.0.0',
-    'foo': '1.0.0'
-  });
-}
-
-unsolvable() {
-  testResolve('no version that matches requirement', {
-    'myapp 0.0.0': {
-      'foo': '>=1.0.0 <2.0.0'
-    },
-    'foo 2.0.0': {},
-    'foo 2.1.3': {}
-  }, error: noVersion(['myapp', 'foo']));
-
-  testResolve('no version that matches combined constraint', {
-    'myapp 0.0.0': {
-      'foo': '1.0.0',
-      'bar': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'shared': '>=2.0.0 <3.0.0'
-    },
-    'bar 1.0.0': {
-      'shared': '>=2.9.0 <4.0.0'
-    },
-    'shared 2.5.0': {},
-    'shared 3.5.0': {}
-  }, error: noVersion(['shared', 'foo', 'bar']));
-
-  testResolve('disjoint constraints', {
-    'myapp 0.0.0': {
-      'foo': '1.0.0',
-      'bar': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'shared': '<=2.0.0'
-    },
-    'bar 1.0.0': {
-      'shared': '>3.0.0'
-    },
-    'shared 2.0.0': {},
-    'shared 4.0.0': {}
-  }, error: disjointConstraint(['shared', 'foo', 'bar']));
-
-  testResolve('mismatched descriptions', {
-    'myapp 0.0.0': {
-      'foo': '1.0.0',
-      'bar': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'shared-x': '1.0.0'
-    },
-    'bar 1.0.0': {
-      'shared-y': '1.0.0'
-    },
-    'shared-x 1.0.0': {},
-    'shared-y 1.0.0': {}
-  }, error: descriptionMismatch('shared', 'foo', 'bar'));
-
-  testResolve('mismatched sources', {
-    'myapp 0.0.0': {
-      'foo': '1.0.0',
-      'bar': '1.0.0'
-    },
-    'foo 1.0.0': {
-      'shared': '1.0.0'
-    },
-    'bar 1.0.0': {
-      'shared from mock2': '1.0.0'
-    },
-    'shared 1.0.0': {},
-    'shared 1.0.0 from mock2': {}
-  }, error: sourceMismatch('shared', 'foo', 'bar'));
-
-  testResolve('no valid solution', {
-    'myapp 0.0.0': {
-      'a': 'any',
-      'b': 'any'
-    },
-    'a 1.0.0': {
-      'b': '1.0.0'
-    },
-    'a 2.0.0': {
-      'b': '2.0.0'
-    },
-    'b 1.0.0': {
-      'a': '2.0.0'
-    },
-    'b 2.0.0': {
-      'a': '1.0.0'
-    }
-  }, error: couldNotSolve, maxTries: 2);
-
-  // This is a regression test for #15550.
-  testResolve('no version that matches while backtracking', {
-    'myapp 0.0.0': {
-      'a': 'any',
-      'b': '>1.0.0'
-    },
-    'a 1.0.0': {},
-    'b 1.0.0': {}
-  }, error: noVersion(['myapp', 'b']), maxTries: 1);
-
-
-  // This is a regression test for #18300.
-  testResolve('...', {
-    "myapp 0.0.0": {
-      "angular": "any",
-      "collection": "any"
-    },
-    "analyzer 0.12.2": {},
-    "angular 0.10.0": {
-      "di": ">=0.0.32 <0.1.0",
-      "collection": ">=0.9.1 <1.0.0"
-    },
-    "angular 0.9.11": {
-      "di": ">=0.0.32 <0.1.0",
-      "collection": ">=0.9.1 <1.0.0"
-    },
-    "angular 0.9.10": {
-      "di": ">=0.0.32 <0.1.0",
-      "collection": ">=0.9.1 <1.0.0"
-    },
-    "collection 0.9.0": {},
-    "collection 0.9.1": {},
-    "di 0.0.37": {"analyzer": ">=0.13.0 <0.14.0"},
-    "di 0.0.36": {"analyzer": ">=0.13.0 <0.14.0"}
-  }, error: noVersion(['analyzer', 'di']), maxTries: 2);
-}
-
-badSource() {
-  testResolve('fail if the root package has a bad source in dep', {
-    'myapp 0.0.0': {
-      'foo from bad': 'any'
-    },
-  }, error: unknownSource('myapp', 'foo', 'bad'));
-
-  testResolve('fail if the root package has a bad source in dev dep', {
-    'myapp 0.0.0': {
-      '(dev) foo from bad': 'any'
-    },
-  }, error: unknownSource('myapp', 'foo', 'bad'));
-
-  testResolve('fail if all versions have bad source in dep', {
-    'myapp 0.0.0': {
-      'foo': 'any'
-    },
-    'foo 1.0.0': {
-      'bar from bad': 'any'
-    },
-    'foo 1.0.1': {
-      'baz from bad': 'any'
-    },
-    'foo 1.0.3': {
-      'bang from bad': 'any'
-    },
-  }, error: unknownSource('foo', 'bar', 'bad'), maxTries: 3);
-
-  testResolve('ignore versions with bad source in dep', {
-    'myapp 1.0.0': {
-      'foo': 'any'
-    },
-    'foo 1.0.0': {
-      'bar': 'any'
-    },
-    'foo 1.0.1': {
-      'bar from bad': 'any'
-    },
-    'foo 1.0.3': {
-      'bar from bad': 'any'
-    },
-    'bar 1.0.0': {}
-  }, result: {
-    'myapp from root': '1.0.0',
-    'foo': '1.0.0',
-    'bar': '1.0.0'
-  }, maxTries: 3);
-}
-
-backtracking() {
-  testResolve('circular dependency on older version', {
-    'myapp 0.0.0': {
-      'a': '>=1.0.0'
-    },
-    'a 1.0.0': {},
-    'a 2.0.0': {
-      'b': '1.0.0'
-    },
-    'b 1.0.0': {
-      'a': '1.0.0'
-    }
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0'
-  }, maxTries: 2);
-
-  // The latest versions of a and b disagree on c. An older version of either
-  // will resolve the problem. This test validates that b, which is farther
-  // in the dependency graph from myapp is downgraded first.
-  testResolve('rolls back leaf versions first', {
-    'myapp 0.0.0': {
-      'a': 'any'
-    },
-    'a 1.0.0': {
-      'b': 'any'
-    },
-    'a 2.0.0': {
-      'b': 'any',
-      'c': '2.0.0'
-    },
-    'b 1.0.0': {},
-    'b 2.0.0': {
-      'c': '1.0.0'
-    },
-    'c 1.0.0': {},
-    'c 2.0.0': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '2.0.0',
-    'b': '1.0.0',
-    'c': '2.0.0'
-  }, maxTries: 2);
-
-  // Only one version of baz, so foo and bar will have to downgrade until they
-  // reach it.
-  testResolve('simple transitive', {
-    'myapp 0.0.0': {'foo': 'any'},
-    'foo 1.0.0': {'bar': '1.0.0'},
-    'foo 2.0.0': {'bar': '2.0.0'},
-    'foo 3.0.0': {'bar': '3.0.0'},
-    'bar 1.0.0': {'baz': 'any'},
-    'bar 2.0.0': {'baz': '2.0.0'},
-    'bar 3.0.0': {'baz': '3.0.0'},
-    'baz 1.0.0': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '1.0.0',
-    'bar': '1.0.0',
-    'baz': '1.0.0'
-  }, maxTries: 3);
-
-  // This ensures it doesn't exhaustively search all versions of b when it's
-  // a-2.0.0 whose dependency on c-2.0.0-nonexistent led to the problem. We
-  // make sure b has more versions than a so that the solver tries a first
-  // since it sorts sibling dependencies by number of versions.
-  testResolve('backjump to nearer unsatisfied package', {
-    'myapp 0.0.0': {
-      'a': 'any',
-      'b': 'any'
-    },
-    'a 1.0.0': { 'c': '1.0.0' },
-    'a 2.0.0': { 'c': '2.0.0-nonexistent' },
-    'b 1.0.0': {},
-    'b 2.0.0': {},
-    'b 3.0.0': {},
-    'c 1.0.0': {},
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0',
-    'b': '3.0.0',
-    'c': '1.0.0'
-  }, maxTries: 2);
-
-  // Tests that the backjumper will jump past unrelated selections when a
-  // source conflict occurs. This test selects, in order:
-  // - myapp -> a
-  // - myapp -> b
-  // - myapp -> c (1 of 5)
-  // - b -> a
-  // It selects a and b first because they have fewer versions than c. It
-  // traverses b's dependency on a after selecting a version of c because
-  // dependencies are traversed breadth-first (all of myapps's immediate deps
-  // before any other their deps).
-  //
-  // This means it doesn't discover the source conflict until after selecting
-  // c. When that happens, it should backjump past c instead of trying older
-  // versions of it since they aren't related to the conflict.
-  testResolve('backjump to conflicting source', {
-    'myapp 0.0.0': {
-      'a': 'any',
-      'b': 'any',
-      'c': 'any'
-    },
-    'a 1.0.0': {},
-    'a 1.0.0 from mock2': {},
-    'b 1.0.0': {
-      'a': 'any'
-    },
-    'b 2.0.0': {
-      'a from mock2': 'any'
-    },
-    'c 1.0.0': {},
-    'c 2.0.0': {},
-    'c 3.0.0': {},
-    'c 4.0.0': {},
-    'c 5.0.0': {},
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0',
-    'b': '1.0.0',
-    'c': '5.0.0'
-  }, maxTries: 2);
-
-  // Like the above test, but for a conflicting description.
-  testResolve('backjump to conflicting description', {
-    'myapp 0.0.0': {
-      'a-x': 'any',
-      'b': 'any',
-      'c': 'any'
-    },
-    'a-x 1.0.0': {},
-    'a-y 1.0.0': {},
-    'b 1.0.0': {
-      'a-x': 'any'
-    },
-    'b 2.0.0': {
-      'a-y': 'any'
-    },
-    'c 1.0.0': {},
-    'c 2.0.0': {},
-    'c 3.0.0': {},
-    'c 4.0.0': {},
-    'c 5.0.0': {},
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0',
-    'b': '1.0.0',
-    'c': '5.0.0'
-  }, maxTries: 2);
-
-  // Similar to the above two tests but where there is no solution. It should
-  // fail in this case with no backtracking.
-  testResolve('backjump to conflicting source', {
-    'myapp 0.0.0': {
-      'a': 'any',
-      'b': 'any',
-      'c': 'any'
-    },
-    'a 1.0.0': {},
-    'a 1.0.0 from mock2': {},
-    'b 1.0.0': {
-      'a from mock2': 'any'
-    },
-    'c 1.0.0': {},
-    'c 2.0.0': {},
-    'c 3.0.0': {},
-    'c 4.0.0': {},
-    'c 5.0.0': {},
-  }, error: sourceMismatch('a', 'myapp', 'b'), maxTries: 1);
-
-  testResolve('backjump to conflicting description', {
-    'myapp 0.0.0': {
-      'a-x': 'any',
-      'b': 'any',
-      'c': 'any'
-    },
-    'a-x 1.0.0': {},
-    'a-y 1.0.0': {},
-    'b 1.0.0': {
-      'a-y': 'any'
-    },
-    'c 1.0.0': {},
-    'c 2.0.0': {},
-    'c 3.0.0': {},
-    'c 4.0.0': {},
-    'c 5.0.0': {},
-  }, error: descriptionMismatch('a', 'myapp', 'b'), maxTries: 1);
-
-  // Dependencies are ordered so that packages with fewer versions are tried
-  // first. Here, there are two valid solutions (either a or b must be
-  // downgraded once). The chosen one depends on which dep is traversed first.
-  // Since b has fewer versions, it will be traversed first, which means a will
-  // come later. Since later selections are revised first, a gets downgraded.
-  testResolve('traverse into package with fewer versions first', {
-    'myapp 0.0.0': {
-      'a': 'any',
-      'b': 'any'
-    },
-    'a 1.0.0': {'c': 'any'},
-    'a 2.0.0': {'c': 'any'},
-    'a 3.0.0': {'c': 'any'},
-    'a 4.0.0': {'c': 'any'},
-    'a 5.0.0': {'c': '1.0.0'},
-    'b 1.0.0': {'c': 'any'},
-    'b 2.0.0': {'c': 'any'},
-    'b 3.0.0': {'c': 'any'},
-    'b 4.0.0': {'c': '2.0.0'},
-    'c 1.0.0': {},
-    'c 2.0.0': {},
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '4.0.0',
-    'b': '4.0.0',
-    'c': '2.0.0'
-  }, maxTries: 2);
-
-  // This is similar to the above test. When getting the number of versions of
-  // a package to determine which to traverse first, versions that are
-  // disallowed by the root package's constraints should not be considered.
-  // Here, foo has more versions of bar in total (4), but fewer that meet
-  // myapp's constraints (only 2). There is no solution, but we will do less
-  // backtracking if foo is tested first.
-  testResolve('take root package constraints into counting versions', {
-    "myapp 0.0.0": {
-      "foo": ">2.0.0",
-      "bar": "any"
-    },
-    "foo 1.0.0": {"none": "2.0.0"},
-    "foo 2.0.0": {"none": "2.0.0"},
-    "foo 3.0.0": {"none": "2.0.0"},
-    "foo 4.0.0": {"none": "2.0.0"},
-    "bar 1.0.0": {},
-    "bar 2.0.0": {},
-    "bar 3.0.0": {},
-    "none 1.0.0": {}
-  }, error: noVersion(["foo", "none"]), maxTries: 2);
-
-  // This sets up a hundred versions of foo and bar, 0.0.0 through 9.9.0. Each
-  // version of foo depends on a baz with the same major version. Each version
-  // of bar depends on a baz with the same minor version. There is only one
-  // version of baz, 0.0.0, so only older versions of foo and bar will
-  // satisfy it.
-  var map = {
-    'myapp 0.0.0': {
-      'foo': 'any',
-      'bar': 'any'
-    },
-    'baz 0.0.0': {}
-  };
-
-  for (var i = 0; i < 10; i++) {
-    for (var j = 0; j < 10; j++) {
-      map['foo $i.$j.0'] = {'baz': '$i.0.0'};
-      map['bar $i.$j.0'] = {'baz': '0.$j.0'};
-    }
-  }
-
-  testResolve('complex backtrack', map, result: {
-    'myapp from root': '0.0.0',
-    'foo': '0.9.0',
-    'bar': '9.0.0',
-    'baz': '0.0.0'
-  }, maxTries: 10);
-
-  // If there's a disjoint constraint on a package, then selecting other
-  // versions of it is a waste of time: no possible versions can match. We need
-  // to jump past it to the most recent package that affected the constraint.
-  testResolve('backjump past failed package on disjoint constraint', {
-    'myapp 0.0.0': {
-      'a': 'any',
-      'foo': '>2.0.0'
-    },
-    'a 1.0.0': {
-      'foo': 'any' // ok
-    },
-    'a 2.0.0': {
-      'foo': '<1.0.0' // disjoint with myapp's constraint on foo
-    },
-    'foo 2.0.0': {},
-    'foo 2.0.1': {},
-    'foo 2.0.2': {},
-    'foo 2.0.3': {},
-    'foo 2.0.4': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0',
-    'foo': '2.0.4'
-  }, maxTries: 2);
-
-  // This is a regression test for #18666. It was possible for the solver to
-  // "forget" that a package had previously led to an error. In that case, it
-  // would backtrack over the failed package instead of trying different
-  // versions of it.
-  testResolve("finds solution with less strict constraint", {
-    "myapp 1.0.0": {
-      "a": "any",
-      "c": "any",
-      "d": "any"
-    },
-    "a 2.0.0": {},
-    "a 1.0.0": {},
-    "b 1.0.0": {"a": "1.0.0"},
-    "c 1.0.0": {"b": "any"},
-    "d 2.0.0": {"myapp": "any"},
-    "d 1.0.0": {"myapp": "<1.0.0"}
-  }, result: {
-    'myapp from root': '1.0.0',
-    'a': '1.0.0',
-    'b': '1.0.0',
-    'c': '1.0.0',
-    'd': '2.0.0'
-  }, maxTries: 3);
-}
-
-sdkConstraint() {
-  var badVersion = '0.0.0-nope';
-  var goodVersion = sdk.version.toString();
-
-  testResolve('root matches SDK', {
-    'myapp 0.0.0': {'sdk': goodVersion }
-  }, result: {
-    'myapp from root': '0.0.0'
-  });
-
-  testResolve('root does not match SDK', {
-    'myapp 0.0.0': {'sdk': badVersion }
-  }, error: couldNotSolve);
-
-  testResolve('dependency does not match SDK', {
-    'myapp 0.0.0': {'foo': 'any'},
-    'foo 0.0.0': {'sdk': badVersion }
-  }, error: couldNotSolve);
-
-  testResolve('transitive dependency does not match SDK', {
-    'myapp 0.0.0': {'foo': 'any'},
-    'foo 0.0.0': {'bar': 'any'},
-    'bar 0.0.0': {'sdk': badVersion }
-  }, error: couldNotSolve);
-
-  testResolve('selects a dependency version that allows the SDK', {
-    'myapp 0.0.0': {'foo': 'any'},
-    'foo 1.0.0': {'sdk': goodVersion },
-    'foo 2.0.0': {'sdk': goodVersion },
-    'foo 3.0.0': {'sdk': badVersion },
-    'foo 4.0.0': {'sdk': badVersion }
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '2.0.0'
-  }, maxTries: 3);
-
-  testResolve('selects a transitive dependency version that allows the SDK', {
-    'myapp 0.0.0': {'foo': 'any'},
-    'foo 1.0.0': {'bar': 'any'},
-    'bar 1.0.0': {'sdk': goodVersion },
-    'bar 2.0.0': {'sdk': goodVersion },
-    'bar 3.0.0': {'sdk': badVersion },
-    'bar 4.0.0': {'sdk': badVersion }
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '1.0.0',
-    'bar': '2.0.0'
-  }, maxTries: 3);
-
-  testResolve('selects a dependency version that allows a transitive '
-              'dependency that allows the SDK', {
-    'myapp 0.0.0': {'foo': 'any'},
-    'foo 1.0.0': {'bar': '1.0.0'},
-    'foo 2.0.0': {'bar': '2.0.0'},
-    'foo 3.0.0': {'bar': '3.0.0'},
-    'foo 4.0.0': {'bar': '4.0.0'},
-    'bar 1.0.0': {'sdk': goodVersion },
-    'bar 2.0.0': {'sdk': goodVersion },
-    'bar 3.0.0': {'sdk': badVersion },
-    'bar 4.0.0': {'sdk': badVersion }
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '2.0.0',
-    'bar': '2.0.0'
-  }, maxTries: 3);
-}
-
-void prerelease() {
-  testResolve('prefer stable versions over unstable', {
-    'myapp 0.0.0': {
-      'a': 'any'
-    },
-    'a 1.0.0': {},
-    'a 1.1.0-dev': {},
-    'a 2.0.0-dev': {},
-    'a 3.0.0-dev': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0'
-  });
-
-  testResolve('use latest allowed prerelease if no stable versions match', {
-    'myapp 0.0.0': {
-      'a': '<2.0.0'
-    },
-    'a 1.0.0-dev': {},
-    'a 1.1.0-dev': {},
-    'a 1.9.0-dev': {},
-    'a 3.0.0': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.9.0-dev'
-  });
-
-  testResolve('use an earlier stable version on a < constraint', {
-    'myapp 0.0.0': {
-      'a': '<2.0.0'
-    },
-    'a 1.0.0': {},
-    'a 1.1.0': {},
-    'a 2.0.0-dev': {},
-    'a 2.0.0': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.1.0'
-  });
-
-  testResolve('prefer a stable version even if constraint mentions unstable', {
-    'myapp 0.0.0': {
-      'a': '<=2.0.0-dev'
-    },
-    'a 1.0.0': {},
-    'a 1.1.0': {},
-    'a 2.0.0-dev': {},
-    'a 2.0.0': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.1.0'
-  });
-}
-
-void override() {
-  testResolve('chooses best version matching override constraint', {
-    'myapp 0.0.0': {
-      'a': 'any'
-    },
-    'a 1.0.0': {},
-    'a 2.0.0': {},
-    'a 3.0.0': {}
-  }, overrides: {
-    'a': '<3.0.0'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '2.0.0'
-  });
-
-  testResolve('uses override as dependency', {
-    'myapp 0.0.0': {},
-    'a 1.0.0': {},
-    'a 2.0.0': {},
-    'a 3.0.0': {}
-  }, overrides: {
-    'a': '<3.0.0'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '2.0.0'
-  });
-
-  testResolve('ignores other constraints on overridden package', {
-    'myapp 0.0.0': {
-      'b': 'any',
-      'c': 'any'
-    },
-    'a 1.0.0': {},
-    'a 2.0.0': {},
-    'a 3.0.0': {},
-    'b 1.0.0': {
-      'a': '1.0.0'
-    },
-    'c 1.0.0': {
-      'a': '3.0.0'
-    }
-  }, overrides: {
-    'a': '2.0.0'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '2.0.0',
-    'b': '1.0.0',
-    'c': '1.0.0'
-  });
-
-  testResolve('backtracks on overidden package for its constraints', {
-    'myapp 0.0.0': {
-      'shared': '2.0.0'
-    },
-    'a 1.0.0': {
-      'shared': 'any'
-    },
-    'a 2.0.0': {
-      'shared': '1.0.0'
-    },
-    'shared 1.0.0': {},
-    'shared 2.0.0': {}
-  }, overrides: {
-    'a': '<3.0.0'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '1.0.0',
-    'shared': '2.0.0'
-  }, maxTries: 2);
-
-  testResolve('override compatible with locked dependency', {
-    'myapp 0.0.0': {
-      'foo': 'any'
-    },
-    'foo 1.0.0': { 'bar': '1.0.0' },
-    'foo 1.0.1': { 'bar': '1.0.1' },
-    'foo 1.0.2': { 'bar': '1.0.2' },
-    'bar 1.0.0': {},
-    'bar 1.0.1': {},
-    'bar 1.0.2': {}
-  }, lockfile: {
-    'foo': '1.0.1'
-  }, overrides: {
-    'foo': '<1.0.2'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '1.0.1',
-    'bar': '1.0.1'
-  });
-
-  testResolve('override incompatible with locked dependency', {
-    'myapp 0.0.0': {
-      'foo': 'any'
-    },
-    'foo 1.0.0': { 'bar': '1.0.0' },
-    'foo 1.0.1': { 'bar': '1.0.1' },
-    'foo 1.0.2': { 'bar': '1.0.2' },
-    'bar 1.0.0': {},
-    'bar 1.0.1': {},
-    'bar 1.0.2': {}
-  }, lockfile: {
-    'foo': '1.0.1'
-  }, overrides: {
-    'foo': '>1.0.1'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '1.0.2',
-    'bar': '1.0.2'
-  });
-
-  testResolve('no version that matches override', {
-    'myapp 0.0.0': {},
-    'foo 2.0.0': {},
-    'foo 2.1.3': {}
-  }, overrides: {
-    'foo': '>=1.0.0 <2.0.0'
-  }, error: noVersion(['myapp']));
-
-  testResolve('override a bad source without error', {
-    'myapp 0.0.0': {
-      'foo from bad': 'any'
-    },
-    'foo 0.0.0': {}
-  }, overrides: {
-    'foo': 'any'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '0.0.0'
-  });
-}
-
-void downgrade() {
-  testResolve("downgrades a dependency to the lowest matching version", {
-    'myapp 0.0.0': {
-      'foo': '>=2.0.0 <3.0.0'
-    },
-    'foo 1.0.0': {},
-    'foo 2.0.0-dev': {},
-    'foo 2.0.0': {},
-    'foo 2.1.0': {}
-  }, lockfile: {
-    'foo': '2.1.0'
-  }, result: {
-    'myapp from root': '0.0.0',
-    'foo': '2.0.0'
-  }, downgrade: true);
-
-  testResolve('use earliest allowed prerelease if no stable versions match '
-      'while downgrading', {
-    'myapp 0.0.0': {
-      'a': '>=2.0.0-dev.1 <3.0.0'
-    },
-    'a 1.0.0': {},
-    'a 2.0.0-dev.1': {},
-    'a 2.0.0-dev.2': {},
-    'a 2.0.0-dev.3': {}
-  }, result: {
-    'myapp from root': '0.0.0',
-    'a': '2.0.0-dev.1'
-  }, downgrade: true);
-}
-
-testResolve(String description, Map packages, {
-    Map lockfile, Map overrides, Map result, FailMatcherBuilder error,
-    int maxTries, bool downgrade: false}) {
-  _testResolve(test, description, packages, lockfile: lockfile,
-      overrides: overrides, result: result, error: error, maxTries: maxTries,
-      downgrade: downgrade);
-}
-
-solo_testResolve(String description, Map packages, {
-    Map lockfile, Map overrides, Map result, FailMatcherBuilder error,
-    int maxTries, bool downgrade: false}) {
-  log.verbosity = log.Verbosity.SOLVER;
-  _testResolve(solo_test, description, packages, lockfile: lockfile,
-      overrides: overrides, result: result, error: error, maxTries: maxTries,
-      downgrade: downgrade);
-}
-
-_testResolve(void testFn(String description, Function body),
-    String description, Map packages, {
-    Map lockfile, Map overrides, Map result, FailMatcherBuilder error,
-    int maxTries, bool downgrade: false}) {
-  if (maxTries == null) maxTries = 1;
-
-  testFn(description, () {
-    var cache = new SystemCache('.');
-    source1 = new MockSource('mock1');
-    source2 = new MockSource('mock2');
-    cache.register(source1);
-    cache.register(source2);
-    cache.sources.setDefault(source1.name);
-
-    // Build the test package graph.
-    var root;
-    packages.forEach((description, dependencies) {
-      var id = parseSpec(description);
-      var package = mockPackage(id, dependencies,
-          id.name == 'myapp' ? overrides : null);
-      if (id.name == 'myapp') {
-        // Don't add the root package to the server, so we can verify that Pub
-        // doesn't try to look up information about the local package on the
-        // remote server.
-        root = package;
-      } else {
-        (cache.sources[id.source] as MockSource).addPackage(
-            id.description, package);
-      }
-    });
-
-    // Clean up the expectation.
-    if (result != null) {
-      var newResult = {};
-      result.forEach((description, version) {
-        var id = parseSpec(description, version);
-        newResult[id.name] = id;
-      });
-      result = newResult;
-    }
-
-    // Parse the lockfile.
-    var realLockFile = new LockFile.empty();
-    if (lockfile != null) {
-      lockfile.forEach((name, version) {
-        version = new Version.parse(version);
-        realLockFile.packages[name] =
-            new PackageId(name, source1.name, version, name);
-      });
-    }
-
-    // Resolve the versions.
-    var future = resolveVersions(
-        downgrade ? SolveType.DOWNGRADE : SolveType.GET,
-        cache.sources, root, lockFile: realLockFile);
-
-    var matcher;
-    if (result != null) {
-      matcher = new SolveSuccessMatcher(result, maxTries);
-    } else if (error != null) {
-      matcher = error(maxTries);
-    }
-
-    expect(future, completion(matcher));
-  });
-}
-
-typedef SolveFailMatcher FailMatcherBuilder(int maxTries);
-
-FailMatcherBuilder noVersion(List<String> packages) {
-  return (maxTries) => new SolveFailMatcher(packages, maxTries,
-      NoVersionException);
-}
-
-FailMatcherBuilder disjointConstraint(List<String> packages) {
-  return (maxTries) => new SolveFailMatcher(packages, maxTries,
-      DisjointConstraintException);
-}
-
-FailMatcherBuilder descriptionMismatch(
-    String package, String depender1, String depender2) {
-  return (maxTries) => new SolveFailMatcher([package, depender1, depender2],
-      maxTries, DescriptionMismatchException);
-}
-
-// If no solution can be found, the solver just reports the last failure that
-// happened during propagation. Since we don't specify the order that solutions
-// are tried, this just validates that *some* failure occurred, but not which.
-SolveFailMatcher couldNotSolve(maxTries) =>
-    new SolveFailMatcher([], maxTries, null);
-
-FailMatcherBuilder sourceMismatch(
-    String package, String depender1, String depender2) {
-  return (maxTries) => new SolveFailMatcher([package, depender1, depender2],
-      maxTries, SourceMismatchException);
-}
-
-unknownSource(String depender, String dependency, String source) {
-  return (maxTries) => new SolveFailMatcher([depender, dependency, source],
-      maxTries, UnknownSourceException);
-}
-
-class SolveSuccessMatcher implements Matcher {
-  /// The expected concrete package selections.
-  final Map<String, PackageId> _expected;
-
-  /// The maximum number of attempts that should have been tried before finding
-  /// the solution.
-  final int _maxTries;
-
-  SolveSuccessMatcher(this._expected, this._maxTries);
-
-  Description describe(Description description) {
-    return description.add(
-        'Solver to use at most $_maxTries attempts to find:\n'
-        '${_listPackages(_expected.values)}');
-  }
-
-  Description describeMismatch(SolveResult result,
-                               Description description,
-                               Map state, bool verbose) {
-    if (!result.succeeded) {
-      description.add('Solver failed with:\n${result.error}');
-      return null;
-    }
-
-    description.add('Resolved:\n${_listPackages(result.packages)}\n');
-    description.add(state['failures']);
-    return description;
-  }
-
-  bool matches(SolveResult result, Map state) {
-    if (!result.succeeded) return false;
-
-    var expected = new Map.from(_expected);
-    var failures = new StringBuffer();
-
-    for (var id in result.packages) {
-      if (!expected.containsKey(id.name)) {
-        failures.writeln('Should not have selected $id');
-      } else {
-        var expectedId = expected.remove(id.name);
-        if (id != expectedId) {
-          failures.writeln('Expected $expectedId, not $id');
-        }
-      }
-    }
-
-    if (!expected.isEmpty) {
-      failures.writeln('Missing:\n${_listPackages(expected.values)}');
-    }
-
-    // Allow 1 here because the greedy solver will only make one attempt.
-    if (result.attemptedSolutions != 1 &&
-        result.attemptedSolutions > _maxTries) {
-      failures.writeln('Took ${result.attemptedSolutions} attempts');
-    }
-
-    if (!failures.isEmpty) {
-      state['failures'] = failures.toString();
-      return false;
-    }
-
-    return true;
-  }
-
-  String _listPackages(Iterable<PackageId> packages) {
-    return '- ${packages.join('\n- ')}';
-  }
-}
-
-class SolveFailMatcher implements Matcher {
-  /// The strings that should appear in the resulting error message.
-  // TODO(rnystrom): This seems to always be package names. Make that explicit.
-  final Iterable<String> _expected;
-
-  /// The maximum number of attempts that should be tried before failing.
-  final int _maxTries;
-
-  /// The concrete error type that should be found, or `null` if any
-  /// [SolveFailure] is allowed.
-  final Type _expectedType;
-
-  SolveFailMatcher(this._expected, this._maxTries, this._expectedType);
-
-  Description describe(Description description) {
-    description.add('Solver should fail after at most $_maxTries attempts.');
-    if (!_expected.isEmpty) {
-      var textList = _expected.map((s) => '"$s"').join(", ");
-      description.add(' The error should contain $textList.');
-    }
-    return description;
-  }
-
-  Description describeMismatch(SolveResult result,
-                               Description description,
-                               Map state, bool verbose) {
-    description.add(state['failures']);
-    return description;
-  }
-
-  bool matches(SolveResult result, Map state) {
-    var failures = new StringBuffer();
-
-    if (result.succeeded) {
-      failures.writeln('Solver succeeded');
-    } else {
-      if (_expectedType != null && result.error.runtimeType != _expectedType) {
-        failures.writeln('Should have error type $_expectedType, got '
-            '${result.error.runtimeType}');
-      }
-
-      var message = result.error.toString();
-      for (var expected in _expected) {
-        if (!message.contains(expected)) {
-          failures.writeln(
-              'Expected error to contain "$expected", got:\n$message');
-        }
-      }
-
-      // Allow 1 here because the greedy solver will only make one attempt.
-      if (result.attemptedSolutions != 1 &&
-          result.attemptedSolutions > _maxTries) {
-        failures.writeln('Took ${result.attemptedSolutions} attempts');
-      }
-    }
-
-    if (!failures.isEmpty) {
-      state['failures'] = failures.toString();
-      return false;
-    }
-
-    return true;
-  }
-}
-
-/// A source used for testing. This both creates mock package objects and acts
-/// as a source for them.
-///
-/// In order to support testing packages that have the same name but different
-/// descriptions, a package's name is calculated by taking the description
-/// string and stripping off any trailing hyphen followed by non-hyphen
-/// characters.
-class MockSource extends CachedSource {
-  final _packages = <String, Map<Version, Package>>{};
-
-  /// Keeps track of which package version lists have been requested. Ensures
-  /// that a source is only hit once for a given package and that pub
-  /// internally caches the results.
-  final _requestedVersions = new Set<String>();
-
-  /// Keeps track of which package pubspecs have been requested. Ensures that a
-  /// source is only hit once for a given package and that pub internally
-  /// caches the results.
-  final _requestedPubspecs = new Map<String, Set<Version>>();
-
-  final String name;
-  final hasMultipleVersions = true;
-
-  MockSource(this.name);
-
-  dynamic parseDescription(String containingPath, description,
-                             {bool fromLockFile: false}) => description;
-
-  bool descriptionsEqual(description1, description2) =>
-      description1 == description2;
-
-  Future<String> getDirectory(PackageId id) {
-    return new Future.value('${id.name}-${id.version}');
-  }
-
-  Future<List<Pubspec>> getVersions(String name, String description) {
-    return new Future.sync(() {
-      // Make sure the solver doesn't request the same thing twice.
-      if (_requestedVersions.contains(description)) {
-        throw new Exception('Version list for $description was already '
-            'requested.');
-      }
-
-      _requestedVersions.add(description);
-
-      if (!_packages.containsKey(description)){
-        throw new Exception('MockSource does not have a package matching '
-            '"$description".');
-      }
-
-      return _packages[description].values
-          .map((package) => package.pubspec).toList();
-    });
-  }
-
-  Future<Pubspec> describeUncached(PackageId id) {
-    return new Future.sync(() {
-      // Make sure the solver doesn't request the same thing twice.
-      if (_requestedPubspecs.containsKey(id.description) &&
-          _requestedPubspecs[id.description].contains(id.version)) {
-        throw new Exception('Pubspec for $id was already requested.');
-      }
-
-      _requestedPubspecs.putIfAbsent(id.description, () => new Set<Version>());
-      _requestedPubspecs[id.description].add(id.version);
-
-      return _packages[id.description][id.version].pubspec;
-    });
-  }
-
-  Future<Package> downloadToSystemCache(PackageId id) =>
-      throw new UnsupportedError('Cannot download mock packages');
-
-  List<Package> getCachedPackages() =>
-      throw new UnsupportedError('Cannot get mock packages');
-
-  Future<Pair<int, int>> repairCachedPackages() =>
-      throw new UnsupportedError('Cannot repair mock packages');
-
-  void addPackage(String description, Package package) {
-    _packages.putIfAbsent(description, () => new Map<Version, Package>());
-    _packages[description][package.version] = package;
-  }
-}
-
-Package mockPackage(PackageId id, Map dependencyStrings, Map overrides) {
-  var sdkConstraint = null;
-
-  // Build the pubspec dependencies.
-  var dependencies = <PackageDep>[];
-  var devDependencies = <PackageDep>[];
-
-  dependencyStrings.forEach((spec, constraint) {
-    var isDev = spec.startsWith("(dev) ");
-    if (isDev) {
-      spec = spec.substring("(dev) ".length);
-    }
-
-    var dep = parseSpec(spec).withConstraint(
-        new VersionConstraint.parse(constraint));
-
-    if (dep.name == 'sdk') {
-      sdkConstraint = dep.constraint;
-      return;
-    }
-
-    if (isDev) {
-      devDependencies.add(dep);
-    } else {
-      dependencies.add(dep);
-    }
-  });
-
-  var dependencyOverrides = <PackageDep>[];
-  if (overrides != null) {
-    overrides.forEach((spec, constraint) {
-      dependencyOverrides.add(parseSpec(spec).withConstraint(
-          new VersionConstraint.parse(constraint)));
-    });
-  }
-
-  return new Package.inMemory(new Pubspec(id.name,
-      version: id.version,
-      dependencies: dependencies,
-      devDependencies: devDependencies,
-      dependencyOverrides: dependencyOverrides,
-      sdkConstraint: sdkConstraint));
-}
-
-/// Creates a new [PackageId] parsed from [text], which looks something like
-/// this:
-///
-///   foo-xyz 1.0.0 from mock
-///
-/// The package name is "foo". A hyphenated suffix like "-xyz" here is part
-/// of the package description, but not its name, so the description here is
-/// "foo-xyz".
-///
-/// This is followed by an optional [Version]. If [version] is provided, then
-/// it is parsed to a [Version], and [text] should *not* also contain a
-/// version string.
-///
-/// The "from mock" optional suffix is the name of a source for the package.
-/// If omitted, it defaults to "mock1".
-PackageId parseSpec(String text, [String version]) {
-  var pattern = new RegExp(r"(([a-z_]*)(-[a-z_]+)?)( ([^ ]+))?( from (.*))?$");
-  var match = pattern.firstMatch(text);
-  if (match == null) {
-    throw new FormatException("Could not parse spec '$text'.");
-  }
-
-  var description = match[1];
-  var name = match[2];
-
-  var parsedVersion;
-  if (version != null) {
-    // Spec string shouldn't also contain a version.
-    if (match[5] != null) {
-      throw new ArgumentError("Spec '$text' should not contain a version "
-          "since '$version' was passed in explicitly.");
-    }
-    parsedVersion = new Version.parse(version);
-  } else {
-    if (match[5] != null) {
-      parsedVersion = new Version.parse(match[5]);
-    } else {
-      parsedVersion = Version.none;
-    }
-  }
-
-  var source = "mock1";
-  if (match[7] != null) {
-    source = match[7];
-    if (source == "root") source = null;
-  }
-
-  return new PackageId(name, source, parsedVersion, description);
-}