move deferred_library_check functionality to a library

lib/deferred_library_check.dart

 // Copyright (c) 2015, 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.
 
-/// A command-line tool that verifies that deferred libraries split the code as
-/// expected.
 /// This tool checks that the output from dart2js meets a given specification,
 /// given in a YAML file. The format of the YAML file is:
 ///
 ///     main:
 ///       packages:
 ///         - some_package
 ///         - other_package
 ///
 ///     foo:
 ///       packages:
 ///         - foo
 ///         - bar
 ///
 ///     baz:
 ///       packages:
 ///         - baz
 ///         - quux
 ///
 /// The YAML file consists of a list of declarations, one for each deferred
 /// part expected in the output. At least one of these parts must be named
 /// "main"; this is the main part that contains the program entrypoint. Each
 /// top-level part contains a list of package names that are expected to be
 /// contained in that part. Any package that is not explicitly listed is
 /// expected to be in the main part. For instance, in the example YAML above
 /// the part named "baz" is expected to contain the packages "baz" and "quux".
 ///
 /// The names for parts given in the specification YAML file (besides "main")
 /// are arbitrary and just used for reporting when the output does not meet the
 /// specification.
-library dart2js_info.bin.deferred_library_check;
+library dart2js_info.deferred_library_check;
 
-import 'dart:async';
-import 'dart:convert';
-import 'dart:io';
+import 'info.dart';
+import 'package:quiver/collection.dart';
 
-import 'package:dart2js_info/info.dart';
-import 'package:quiver/collection.dart';
-import 'package:yaml/yaml.dart';
-
-Future main(List<String> args) async {
-  if (args.length < 2) {
-    usage();
-    exit(1);
-  }
-  var info = await infoFromFile(args[0]);
-  var manifest = await manifestFromFile(args[1]);
-
+List<ManifestComplianceFailure> checkDeferredLibraryManifest(
+    AllInfo info, Map manifest) {
   // For each part in the manifest, record the expected "packages" for that
   // part.
   var packages = <String, String>{};
   for (var part in manifest.keys) {
     for (var package in manifest[part]['packages']) {
       if (packages.containsKey(package)) {
-        print('You cannot specify that package "$package" maps to both parts '
+        throw new ArgumentError.value(
+            manifest,
+            'manifest',
+            'You cannot specify that package "$package" maps to both parts '
             '"$part" and "${packages[package]}".');
-        exit(1);
       }
       packages[package] = part;
     }
   }
 
   var guessedPartMapping = new BiMap<String, String>();
   guessedPartMapping['main'] = 'main';
 
-  bool anyFailed = false;
+  var failures = <ManifestComplianceFailure>[];
 
   checkInfo(BasicInfo info) {
-    var lib = getLibraryOf(info);
-    if (lib != null && isPackageUri(lib.uri)) {
-      var packageName = getPackageName(lib.uri);
+    var lib = _getLibraryOf(info);
+    if (lib != null && _isPackageUri(lib.uri)) {
+      var packageName = _getPackageName(lib.uri);
       var outputUnitName = info.outputUnit.name;
       var expectedPart;
       if (packages.containsKey(packageName)) {
         expectedPart = packages[packageName];
       } else {
         expectedPart = 'main';
       }
       var expectedOutputUnit = guessedPartMapping[expectedPart];
       if (expectedOutputUnit == null) {
         guessedPartMapping[expectedPart] = outputUnitName;
       } else {
         if (expectedOutputUnit != outputUnitName) {
           // TODO(het): add options for how to treat unspecified packages
           if (!packages.containsKey(packageName)) {
-            print('"${info.name}" from package "$packageName" was not declared '
-                'to be in an explicit part but was not in the main part');
+            failures.add(new ManifestComplianceFailure(info.name, packageName));
           } else {
             var actualPart = guessedPartMapping.inverse[outputUnitName];
-            print('"${info.name}" from package "$packageName" was specified to '
-                'be in part $expectedPart but is in part $actualPart');
+            failures.add(new ManifestComplianceFailure(
+                info.name, packageName, expectedPart, actualPart));
           }
-          anyFailed = true;
         }
       }
     }
   }
 
   info.functions.forEach(checkInfo);
   info.fields.forEach(checkInfo);
-  if (anyFailed) {
-    print('The dart2js output did not meet the specification.');
-  } else {
-    print('The dart2js output meets the specification');
-  }
+
+  return failures;
 }
 
-LibraryInfo getLibraryOf(Info info) {
+LibraryInfo _getLibraryOf(Info info) {
   var current = info;
   while (current is! LibraryInfo) {
     if (current == null) {
       return null;
     }
     current = current.parent;
   }
   return current;
 }
 
-bool isPackageUri(Uri uri) => uri.scheme == 'package';
+bool _isPackageUri(Uri uri) => uri.scheme == 'package';
 
-String getPackageName(Uri uri) {
-  assert(isPackageUri(uri));
+String _getPackageName(Uri uri) {
+  assert(_isPackageUri(uri));
   return uri.pathSegments.first;
 }
 
-Future<AllInfo> infoFromFile(String fileName) async {
-  var file = await new File(fileName).readAsString();
-  return new AllInfoJsonCodec().decode(JSON.decode(file));
+class ManifestComplianceFailure {
+  final String infoName;
+  final String packageName;
+  final String expectedPart;
+  final String actualPart;
+
+  const ManifestComplianceFailure(this.infoName, this.packageName,
+      [this.expectedPart, this.actualPart]);
+
+  String toString() {
+    if (expectedPart == null && actualPart == null) {
+      return '"$infoName" from package "$packageName" was not declared '
+          'to be in an explicit part but was not in the main part';
+    } else {
+      return '"$infoName" from package "$packageName" was specified to '
+          'be in part $expectedPart but is in part $actualPart';
+    }
+  }
 }
-
-Future manifestFromFile(String fileName) async {
-  var file = await new File(fileName).readAsString();
-  return loadYaml(file);
-}
-
-void usage() {
-  print('''
-usage: dart2js_info_deferred_library_check dump.info.json manifest.yaml''');
-}