Make pub generate .packages file.

test/descriptor.dart

Index: test/descriptor.dart
diff --git a/test/descriptor.dart b/test/descriptor.dart
index 9890ba3685e691572fa65bcd92688f670bd64cce..f5c7601383a84b2b087222ebaeeb243d4a8ed730 100644
--- a/test/descriptor.dart
+++ b/test/descriptor.dart
@@ -5,11 +5,16 @@
 /// Pub-specific scheduled_test descriptors.
 library descriptor;
 
+import "dart:io" show File;
+
 import 'package:oauth2/oauth2.dart' as oauth2;
+import 'package:path/path.dart' as p;
 import 'package:pub/src/io.dart';
 import 'package:pub/src/utils.dart';
 import 'package:scheduled_test/descriptor.dart';
 import 'package:scheduled_test/scheduled_server.dart';
+import 'package:package_config/packages_file.dart' as packages_file;
+import 'package:stack_trace/stack_trace.dart';
 
 import 'descriptor/git.dart';
 import 'descriptor/tar.dart';
@@ -182,3 +187,80 @@ Descriptor credentialsFile(
 /// the given [dependencies].
 DirectoryDescriptor appDir([Map dependencies]) =>
   dir(appPath, [appPubspec(dependencies)]);
+
+/// Describes a `.packages` file.
+///
+/// The [dependencies] maps package names to version strings.

[nweiz, 2015/06/12 23:48:08]

Remove "The"

[Lasse Reichstein Nielsen, 2015/06/23 14:54:33]

Done.

+///
+/// Validation checks that the `.packages` file exists, has the expected
+/// entries (one per key in []) with a path that contains the version string.

[nweiz, 2015/06/12 23:48:08]

"[]" -> "[dependencies]"

[Lasse Reichstein Nielsen, 2015/06/23 14:54:34]

Done.

+Descriptor packagesFile([Map dependencies]) =>
+  new _PackagesFileDescriptor(dependencies);
+
+class _PackagesFileDescriptor extends Descriptor {

[nweiz, 2015/06/12 23:48:08]

This is big enough now it probably warrants its own file under descriptor/.

[Lasse Reichstein Nielsen, 2015/06/23 14:54:33]

Done.

+  final _dependencies;
+
+  _PackagesFileDescriptor([Map<String, String> contents])
+      : _dependencies = contents, super('.packages');
+
+  Future create([String parent]) => schedule(() {
+    if (parent == null) parent = defaultRoot;
+    var contents = const <int>[];
+    if (_dependencies != null) {
+      var mapping = {};
+      _dependencies.forEach((k, v) {

[nweiz, 2015/06/12 23:48:08]

Nit: use full words for variables. Also, something semantic like "package" and
"version" would be preferable to "key" and "value".

[Lasse Reichstein Nielsen, 2015/06/23 14:54:33]

Done.

+        mapping[k] = p.toUri(p.join(cachePath, "$k-$v", "lib", ""));
+      });
+      var buffer = new StringBuffer();
+      packages_file.write(buffer, mapping);
+      contents = UTF8.encode(buffer.toString());
+    }
+    return Chain.track(new File(p.join(parent, name))

[nweiz, 2015/06/12 23:48:08]

Chain.track isn't necessary here anymore.

[Lasse Reichstein Nielsen, 2015/06/23 14:54:33]

Done.

+        .writeAsBytes(contents));
+  }, "creating file '$name'");
+
+  Future validate([String parent]) =>
+    schedule(() => validateNow(parent), "validating file '$name'");
+
+  Future validateNow([String parent]) {
+    // Copied from FileDescriptor in scheduled_test.
+    if (parent == null) parent = defaultRoot;
+    var fullPath = p.join(parent, name);
+    if (!new File(fullPath).existsSync()) {
+      fail("File not found: '$fullPath'.");
+    }
+    return Chain.track(new File(fullPath).readAsBytes())

[nweiz, 2015/06/12 23:48:08]

Ditto.

[Lasse Reichstein Nielsen, 2015/06/23 14:54:33]

Done.

+                .then((bytes) => _validateNow(bytes, fullPath));
+  }
+
+  // TODO(nweiz): rather than setting up an inheritance chain, just store a
+  // Matcher for validation. This would require better error messages from the
+  // matcher library, though.

[nweiz, 2015/06/12 23:48:08]

Remove this TODO.

[Lasse Reichstein Nielsen, 2015/06/23 14:54:34]

Done.

+  /// A function that throws an error if [binaryContents] doesn't match the
+  /// expected contents of the descriptor.
+  void _validateNow(List<int> binaryContents, String fullPath) {
+    var fileUri = p.toUri(fullPath);
+    var map = packages_file.parse(binaryContents, fileUri);
+
+    for (var packageName in _dependencies.keys) {
+      if (!map.containsKey(packageName)) {
+        fail(".packages does not contain $packageName entry");
+      }
+      var version = _dependencies[packageName];
+      if (!map[packageName].path.contains(version)) {
+        fail(".packages of $packageName has incorrect version. "
+             "Expected $version, found location: ${map[packageName]}.");
+      }
+    }
+
+    if (map.length != _dependencies.length) {
+      for (var key in map.keys) {
+        if (!_dependencies.containsKey(key)) {
+          fail(".packages file contains unexpected entry: $key");
+        }
+      }
+    }
+  }
+
+  String describe() => name;
+}