// 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_update_test;

import 'dart:async';
import 'dart:io';

import 'package:unittest/unittest.dart';

import '../lib/src/lock_file.dart';
import '../lib/src/package.dart';
import '../lib/src/pubspec.dart';
import '../lib/src/sdk.dart' as sdk;
import '../lib/src/source.dart';
import '../lib/src/source_registry.dart';
import '../lib/src/system_cache.dart';
import '../lib/src/utils.dart';
import '../lib/src/version.dart';
import '../lib/src/solver/version_solver.dart';
import 'test_pub.dart';

MockSource source1;
MockSource source2;

main() {
  initConfig();

  // 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('backtracking', backtracking);
  group('SDK constraint', sdkConstraint);
}

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('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']));

  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(['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(['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('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('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);
}

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);

  // 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 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);

  // TODO(rnystrom): More tests. In particular:
  // - Tests that demonstrate backtracking for every case that can cause a
  //   solution to fail (no versions, disjoint, etc.)
  // - Tests where there are multiple valid solutions and "best" is possibly
  //   ambiguous to nail down which order the backtracker tries solutions.
}

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);

  testResolve('ignores SDK constraints on bleeding edge', {
    'myapp 0.0.0': {'sdk': badVersion }
  }, result: {
    'myapp from root': '0.0.0'
  }, useBleedingEdgeSdkVersion: true);
}

testResolve(description, packages,
            {lockfile, result, FailMatcherBuilder error, int maxTries,
             bool useBleedingEdgeSdkVersion}) {
  if (maxTries == null) maxTries = 1;
  if (useBleedingEdgeSdkVersion == null) useBleedingEdgeSdkVersion = false;

  test(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((nameVersion, dependencies) {
      var parsed = parseSource(nameVersion, (isDev, nameVersion, source) {
        var parts = nameVersion.split(' ');
        var name = parts[0];
        var version = parts[1];

        var package = mockPackage(name, version, dependencies);
        if (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 {
          source.addPackage(name, package);
        }
      });
    });

    // Clean up the expectation.
    if (result != null) {
      var newResult = {};
      result.forEach((name, version) {
        parseSource(name, (isDev, name, source) {
          version = new Version.parse(version);
          newResult[name] = new PackageId(name, source, version, name);
        });
      });
      result = newResult;
    }

    var realLockFile = new LockFile.empty();
    if (lockfile != null) {
      lockfile.forEach((name, version) {
        version = new Version.parse(version);
        realLockFile.packages[name] =
          new PackageId(name, source1, version, name);
      });
    }

    // Make a version number like the continuous build's version.
    var previousVersion = sdk.version;
    if (useBleedingEdgeSdkVersion) {
      sdk.version = new Version(0, 1, 2, build: '0_r12345_juser');
    }

    // Resolve the versions.
    var future = resolveVersions(cache.sources, root,
        lockFile: realLockFile);

    var matcher;
    if (result != null) {
      matcher = new SolveSuccessMatcher(result, maxTries);
    } else if (error != null) {
      matcher = error(maxTries);
    }

    future = future.whenComplete(() {
      if (useBleedingEdgeSdkVersion) {
        sdk.version = previousVersion;
      }
    });

    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 package1, String package2) {
  return (maxTries) => new SolveFailMatcher([package1, package2], 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 package1, String package2) {
  return (maxTries) => new SolveFailMatcher([package1, package2], maxTries,
      SourceMismatchException);
}

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,
                               MatchState state, bool verbose) {
    if (!result.succeeded) {
      description.add('Solver failed with:\n${result.error}');
      return;
    }

    description.add('Resolved:\n${_listPackages(result.packages)}\n');
    description.add(state.state);
    return description;
  }

  bool matches(SolveResult result, MatchState 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.state = 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,
                               MatchState state, bool verbose) {
    description.add(state.state);
    return description;
  }

  bool matches(SolveResult result, MatchState 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.state = 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 Source {
  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;
  bool get shouldCache => true;

  MockSource(this.name);

  Future<String> systemCacheDirectory(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> describe(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<bool> install(PackageId id, String path) {
    throw new Exception('no');
  }

  void addPackage(String description, Package package) {
    _packages.putIfAbsent(description, () => new Map<Version, Package>());
    _packages[description][package.version] = package;
  }
}

Package mockPackage(String description, String version,
                    Map dependencyStrings) {
  var sdkConstraint = null;

  // Build the pubspec dependencies.
  var dependencies = <PackageDep>[];
  var devDependencies = <PackageDep>[];

  dependencyStrings.forEach((name, constraint) {
    parseSource(name, (isDev, name, source) {
      var packageName = name.replaceFirst(new RegExp(r"-[^-]+$"), "");
      constraint = new VersionConstraint.parse(constraint);

      if (name == 'sdk') {
        sdkConstraint = constraint;
        return;
      }

      var dep = new PackageDep(packageName, source, constraint, name);

      if (isDev) {
        devDependencies.add(dep);
      } else {
        dependencies.add(dep);
      }
    });
  });

  var name = description.replaceFirst(new RegExp(r"-[^-]+$"), "");
  var pubspec = new Pubspec(
      name, new Version.parse(version), dependencies, devDependencies,
      new PubspecEnvironment(sdkConstraint));
  return new Package.inMemory(pubspec);
}

void parseSource(String description,
    callback(bool isDev, String name, Source source)) {
  var isDev = false;

  if (description.startsWith("(dev) ")) {
    description = description.substring("(dev) ".length);
    isDev = true;
  }

  var name = description;
  var source = source1;

  var sourceNames = {
    'mock1': source1,
    'mock2': source2,
    'root': null
  };

  var match = new RegExp(r"(.*) from (.*)").firstMatch(description);
  if (match != null) {
    name = match[1];
    source = sourceNames[match[2]];
  }

  callback(isDev, name, source);
}