Test pub against older source_maps versions when using older barback versions.

sdk/lib/_internal/pub/test/test_pub.dart

 // Copyright (c) 2013, 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.
 
 /// Test infrastructure for testing pub.
 ///
 /// Unlike typical unit tests, most pub tests are integration tests that stage
 /// some stuff on the file system, run pub, and then validate the results. This
 /// library provides an API to build tests like that.
 library test_pub;
@@ skipping 56 matching lines @@
 /// A [Matcher] that matches JavaScript generated by dart2js with minification
 /// enabled.
 Matcher isMinifiedDart2JSOutput =
     isNot(contains("// The code supports the following hooks"));
 
 /// A [Matcher] that matches JavaScript generated by dart2js with minification
 /// disabled.
 Matcher isUnminifiedDart2JSOutput =
     contains("// The code supports the following hooks");
 
-/// The directory containing the version of barback that should be used for this
-/// test.
-String _barbackDir;
+/// A map from package names to paths from which those packages should be loaded
+/// for [createLockFile].
+///
+/// This allows older versions of dependencies than those that exist in the repo
+/// to be used when testing pub.
+Map<String, String> _packageOverrides;
 
 /// A map from barback versions to the paths of directories in the repo
 /// containing them.
 ///
 /// This includes the latest version of barback from pkg as well as all old
 /// versions of barback in third_party.
 final _barbackVersions = _findBarbackVersions();
 
+/// Some older barback versions require older versions of barback's dependencies
+/// than those that are in the repo.
+///
+/// This is a map from barback version ranges to the dependencies for those
+/// barback versions. Each dependency version listed here should be included in
+/// third_party/pkg.
+final _barbackDeps = {
+  new VersionConstraint.parse("<0.15.0"): {
+    "source_maps": "0.9.4"
+  }
+};
+
 /// Populates [_barbackVersions].
 Map<Version, String> _findBarbackVersions() {
   var versions = {};
   var currentBarback = path.join(repoRoot, 'pkg', 'barback');
   versions[new Pubspec.load(currentBarback, new SourceRegistry()).version] =
       currentBarback;
 
   for (var dir in listDir(path.join(repoRoot, 'third_party', 'pkg'))) {
     var basename = path.basename(dir);
     if (!basename.startsWith('barback')) continue;
@@ skipping 14 matching lines @@
 
   var validVersions = _barbackVersions.keys.where(constraint.allows);
   if (validVersions.isEmpty) {
     throw new ArgumentError(
         'No available barback version matches "$versionConstraint".');
   }
 
   for (var version in validVersions) {
     group("with barback $version", () {
       setUp(() {
-        _barbackDir = _barbackVersions[version];
+        _packageOverrides = {};
+        _packageOverrides['barback'] = _barbackVersions[version];
+        _barbackDeps.forEach((constraint, deps) {
+          if (!constraint.allows(version)) return;
+          deps.forEach((packageName, version) {
+            _packageOverrides[packageName] = path.join(
+                repoRoot, 'third_party', 'pkg', '$packageName-$version');
+          });
+        });
+
+        currentSchedule.onComplete.schedule(() {
+          _packageOverrides = null;
+        });
       });
 
       callback();
     });
   }
 }
 
 /// The completer for [port].
 Completer<int> get _portCompleter {
   if (_portCompleterCache != null) return _portCompleterCache;
@@ skipping 649 matching lines @@
     for (var package in sandbox) {
       dependencies[package] = '../$package';
     }
   }
 
   if (pkg != null) {
     _addPackage(String package) {
       if (dependencies.containsKey(package)) return;
 
       var packagePath;
-      if (package == 'barback') {
-        if (_barbackDir == null) {
-          throw new StateError("createLockFile() can only create a lock file "
-              "with a barback dependency within a withBarbackVersions() "
-              "block.");
-        }
-        packagePath = _barbackDir;
+      if (package == 'barback' && _packageOverrides == null) {
+        throw new StateError("createLockFile() can only create a lock file "
+            "with a barback dependency within a withBarbackVersions() "
+            "block.");
+      }
+
+      if (_packageOverrides.containsKey(package)) {
+        packagePath = _packageOverrides[package];
       } else {
         packagePath = path.join(pkgPath, package);
       }
 
       dependencies[package] = packagePath;
       var pubspec = loadYaml(
           readTextFile(path.join(packagePath, 'pubspec.yaml')));
       var packageDeps = pubspec['dependencies'];
       if (packageDeps == null) return;
       packageDeps.keys.forEach(_addPackage);
@@ skipping 203 matching lines @@
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     return description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }
 
 /// A [StreamMatcher] that matches multiple lines of output.
 StreamMatcher emitsLines(String output) => inOrder(output.split("\n"));