- Properly return null if an unknown package is resolved.

- Allow short form package:foo imports.

R=asiva@google.com

Review URL: https://codereview.chromium.org/1822863002 .

runtime/bin/builtin.dart

@@ -295,7 +295,18 @@ Uri _resolvePackageUri(Uri uri) {
     if (mapping == null) {
       throw "No mapping for '$packageName' package when resolving '$uri'.";
     }
-    var path = uri.path.substring(packageName.length + 1);
+    var path;
+    if (uri.path.length > packageName.length) {
+      path = uri.path.substring(packageName.length + 1);
+    } else {
+      // Handle naked package resolution to the default package name:
+      // package:foo is equivalent to package:foo/foo.dart
+      assert(uri.path.length == packageName.length);
+      path = "$packageName.dart";
+    }
+    if (_traceLoading) {
+      _log("Path to be resolved in package: $path");
+    }
     resolvedUri = mapping.resolve(path);
   }
   if (_traceLoading) {
@@ -754,7 +765,17 @@ Future<Uri> _resolvePackageUriFuture(Uri packageUri) async {
   }
   assert(_packagesReady);
 
-  var result = _resolvePackageUri(packageUri);
+  var result;
+  try {
+    result = _resolvePackageUri(packageUri);
+  } catch (e, s) {
+    // Any error during resolution will resolve this package as not mapped,
+    // which is indicated by a null return.
+    if (_traceLoading) {
+      _log("Exception ($e) when resolving package URI: $packageUri");
+    }
+    result = null;
+  }
   if (_traceLoading) {
     _log("Resolved '$packageUri' to '$result'");
   }

tests/isolate/scenarios/bad_resolve_package/.packages

@@ -0,0 +1 @@
+# Intentionally left blank to ensure no packages are resolved.

tests/isolate/scenarios/bad_resolve_package/bad_resolve_package_test.dart

@@ -0,0 +1,47 @@
+// Copyright (c) 2016, 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.
+
+// PackageRoot=none
+
+import 'dart:io';
+import 'dart:isolate';
+
+main([args, port]) async {
+  if (port != null) {
+    testBadResolvePackage(port);
+    return;
+  }
+  var p = new RawReceivePort();
+  Isolate.spawnUri(Platform.script, [], p.sendPort);
+  p.handler = (msg) {
+    p.close();
+    if (msg is! List) {
+      print(msg.runtimeType);
+      throw "Failure return from spawned isolate:\n\n$msg";
+    }
+    // Expecting a null resolution for inexistent package mapping.
+    if (msg[0] != null) {
+      throw "Bad package config in child isolate: ${msg[0]}\n"
+            "Expected: 'Foo'";
+    }
+    print("SUCCESS");
+  };
+}
+
+testBadResolvePackage(port) async {
+  try {
+    var packageRootStr = Platform.packageRoot;
+    var packageConfigStr = Platform.packageConfig;
+    var packageConfig = await Isolate.packageConfig;
+    var badPackageUri = Uri.parse("package:asdf/qwerty.dart");
+    var resolvedPkg = await Isolate.resolvePackageUri(badPackageUri);
+    print("Spawned isolate's package root flag: $packageRootStr");
+    print("Spawned isolate's package config flag: $packageConfigStr");
+    print("Spawned isolate's loaded package config: $packageConfig");
+    print("Spawned isolate's resolved package path: $resolvedPkg");
+    port.send([resolvedPkg]);
+  } catch (e, s) {
+    port.send("$e\n$s\n");
+  }
+}

tests/isolate/scenarios/short_package/.packages

@@ -0,0 +1 @@
+flu:flu_package/

tests/isolate/scenarios/short_package/flu_package/flu.dart

@@ -0,0 +1,3 @@
+class Flu {
+  static var value = "Flu";
+}

tests/isolate/scenarios/short_package/flu_package/flu.text

@@ -0,0 +1 @@
+Bar

tests/isolate/scenarios/short_package/short_package_test.dart

@@ -0,0 +1,37 @@
+// Copyright (c) 2016, 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.
+
+// PackageRoot=none
+
+import 'dart:io';
+import 'dart:isolate';
+
+import "package:flu";
+
+var PACKAGE_FLU = "package:flu";
+var FLU_TEXT = "flu.text";
+
+testShortResolution(package_uri) async {
+  var fluPackage = await Isolate.resolvePackageUri(Uri.parse(package_uri));
+  print("Resolved $package_uri to $fluPackage");
+  var fluText = fluPackage.resolve(FLU_TEXT);
+  print("Resolved $FLU_TEXT from $package_uri to $fluText");
+  var fluFile = new File.fromUri(fluText);
+  var fluString = await fluFile.readAsString();
+  if (fluString != "Bar") {
+    throw "Contents of $FLU_TEXT not matching.\n"
+          "Got: $fluString\n"
+          "Expected: Bar";
+  }
+}
+
+main([args, port]) async {
+  if (Flu.value != "Flu") {
+    throw "Import of wrong Flu package.";
+  }
+  await testShortResolution(PACKAGE_FLU);
+  await testShortResolution(PACKAGE_FLU + "/");
+  await testShortResolution(PACKAGE_FLU + "/abc.def");
+  print("SUCCESS");
+}