// 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'
  });
}

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: 3);
}

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: 4);

  // 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(['myapp', 'angular', 'collection']), maxTries: 9);
}

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: 100);

  // 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<Version>> 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].keys.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);
}