Support serving from multiple directories using "pub serve".

sdk/lib/_internal/pub/lib/src/command/serve.dart

Index: sdk/lib/_internal/pub/lib/src/command/serve.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command/serve.dart b/sdk/lib/_internal/pub/lib/src/command/serve.dart
index a03bdd9904d967b2992395de588b146178c9a413..eb7c517ff0b0e4ff93361c4fb6d16273e7a11ee3 100644
--- a/sdk/lib/_internal/pub/lib/src/command/serve.dart
+++ b/sdk/lib/_internal/pub/lib/src/command/serve.dart
@@ -5,8 +5,10 @@
 library pub.command.serve;
 
 import 'dart:async';
+import 'dart:math' as math;
 
 import 'package:barback/barback.dart';
+import 'package:path/path.dart' as p;
 
 import '../barback/build_environment.dart';
 import '../barback/pub_package_provider.dart';
@@ -20,8 +22,12 @@ final _arrow = getSpecial('\u2192', '=>');
 
 /// Handles the `serve` pub command.
 class ServeCommand extends PubCommand {
-  String get description => "Run a local web development server.";
-  String get usage => "pub serve";
+  String get description =>
+      'Run a local web development server.\n\n'
+      'By default, this serves "web/" and "test/", but an explicit list of \n'
+      'directories to serve can be provided as well.';
+  String get usage => "pub serve [directories...]";
+  final takesArguments = true;
 
   PubPackageProvider _provider;
 
@@ -35,7 +41,7 @@ class ServeCommand extends PubCommand {
 
   ServeCommand() {
     commandParser.addOption('port', defaultsTo: '8080',
-        help: 'The port to listen on.');
+        help: 'The base port to listen on.');
 
     // A hidden option for the tests to work around a bug in some of the OS X
     // bots where "localhost" very rarely resolves to the IPv4 loopback address
@@ -66,24 +72,26 @@ class ServeCommand extends PubCommand {
         WatcherType.POLLING : WatcherType.AUTO;
 
     return BuildEnvironment.create(entrypoint, hostname, port, mode,
-        watcherType, ["web"].toSet(),
+        watcherType, _directoriesToServe,
         useDart2JS: useDart2JS).then((environment) {
 
       // In release mode, strip out .dart files since all relevant ones have
       // been compiled to JavaScript already.
       if (mode == BarbackMode.RELEASE) {
-        environment.server.allowAsset = (url) => !url.path.endsWith(".dart");
+        for (var server in environment.servers) {
+          server.allowAsset = (url) => !url.path.endsWith(".dart");
+        }
       }
 
       /// This completer is used to keep pub running (by not completing) and
       /// to pipe fatal errors to pub's top-level error-handling machinery.
       var completer = new Completer();
 
-      environment.server.barback.errors.listen((error) {
+      environment.barback.errors.listen((error) {
         log.error(log.red("Build error:\n$error"));
       });
 
-      environment.server.barback.results.listen((result) {
+      environment.barback.results.listen((result) {
         if (result.succeeded) {
           // TODO(rnystrom): Report using growl/inotify-send where available.
           log.message("Build completed ${log.green('successfully')}");
@@ -95,28 +103,83 @@ class ServeCommand extends PubCommand {
         if (!completer.isCompleted) completer.completeError(error, stackTrace);
       });
 
-      environment.server.results.listen((result) {
-        if (result.isSuccess) {
-          log.message("${log.green('GET')} ${result.url.path} $_arrow "
-              "${result.id}");
-          return;
-        }
-
-        var msg = "${log.red('GET')} ${result.url.path} $_arrow";
-        var error = result.error.toString();
-        if (error.contains("\n")) {
-          log.message("$msg\n${prefixLines(error)}");
-        } else {
-          log.message("$msg $error");
-        }
-      }, onError: (error, [stackTrace]) {
-        if (!completer.isCompleted) completer.completeError(error, stackTrace);
-      });
-
-      log.message("Serving ${entrypoint.root.name} "
-          "on http://$hostname:${environment.server.port}");
+      var directoryLength = environment.servers
+          .map((server) => server.rootDirectory.length)
+          .reduce(math.max);
+      for (var server in environment.servers) {
+        // Add two characters to account for "[" and "]".
+        var directoryPrefix = log.gray(
+            padRight("[${server.rootDirectory}]", directoryLength + 2));
+        server.results.listen((result) {
+          if (result.isSuccess) {
+            log.message("$directoryPrefix ${log.green('GET')} "
+                "${result.url.path} $_arrow ${result.id}");
+            return;
+          }
+
+          var msg = "$directoryPrefix ${log.red('GET')} ${result.url.path} "
+              "$_arrow";
+          var error = result.error.toString();
+          if (error.contains("\n")) {
+            log.message("$msg\n${prefixLines(error)}");
+          } else {
+            log.message("$msg $error");
+          }
+        }, onError: (error, [stackTrace]) {
+          if (completer.isCompleted) return;
+          completer.completeError(error, stackTrace);
+        });
+
+        log.message("Serving ${entrypoint.root.name} "
+            "${padRight(server.rootDirectory, directoryLength)} "
+            "on ${log.bold('http://$hostname:${server.port}')}");
+      }
 
       return completer.future;
     });
   }
+
+  /// Returns the set of directories that will be served from servers exposed to
+  /// the user.
+  ///
+  /// Throws a [UsageException] if the command-line arguments are invalid.
+  List<String> get _directoriesToServe {
+    if (commandOptions.rest.isEmpty) {
+      var directories = ['web', 'test'].where(dirExists).toList();
+      if (directories.isNotEmpty) return directories;
+      usageError(
+          'Your package must have "web" and/or "test" directories to serve,\n'
+          'or you must pass in directories to serve explicitly.');
+    }
+
+    var directories = commandOptions.rest.map(p.normalize).toList();
+    var invalid = directories.where((dir) => !isBeneath(dir, '.'));
+    if (invalid.isNotEmpty) {
+      usageError("${_directorySentence(invalid, "isn't", "aren't")} in this "
+          "package.");
+    }
+
+    var nonExistent = directories.where((dir) => !dirExists(dir));
+    if (nonExistent.isNotEmpty) {
+      usageError("${_directorySentence(nonExistent, "doesn't", "don't")} "
+          "exist.");
+    }
+
+    return directories;
+  }
+
+  /// Converts a list of [directoryNames] to a sentence.
+  ///
+  /// After the list of directories, [singularVerb] will be used if there is
+  /// only one directory and [pluralVerb] will be used if there are more than
+  /// one.
+  String _directorySentence(Iterable<String> directoryNames,
+      String singularVerb, String pluralVerb) {
+    var directories = pluralize('Directory', directoryNames.length,
+        plural: 'Directories');
+    var names = toSentence(ordered(directoryNames).map((dir) => '"$dir"'));
+    var verb = pluralize(singularVerb, directoryNames.length,
+        plural: pluralVerb);
+    return "$directories $names $verb";
+  }
 }