cache pub list results

pkg/analyzer/lib/source/pub_package_map_provider.dart

 // Copyright (c) 2014, 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.
 
 library source.pub_package_map_provider;
 
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io' as io;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/source/package_map_provider.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk_io.dart';
 import 'package:path/path.dart';
 
 /**
+ * The function used to run pub list.
+ */
+typedef io.ProcessResult RunPubList(Folder folder);
+
+/**
  * Implementation of PackageMapProvider that operates by executing pub.
  */
 class PubPackageMapProvider implements PackageMapProvider {
   static const String PUB_LIST_COMMAND = 'list-package-dirs';
 
   /**
    * The name of the 'pubspec.lock' file, which we assume is the dependency
    * in the event that [PUB_LIST_COMMAND] fails.
    */
   static const String PUBSPEC_LOCK_NAME = 'pubspec.lock';
 
   /**
    * [ResourceProvider] that is used to create the [Folder]s that populate the
    * package map.
    */
   final ResourceProvider resourceProvider;
 
   /**
    * Sdk that we use to find the pub executable.
    */
   final DirectoryBasedDartSdk sdk;
 
-  PubPackageMapProvider(this.resourceProvider, this.sdk);
+  /**
+   * The function used to run pub list.
+   */
+  RunPubList _runPubList;
+
+  /**
+   * Construct a new instance.
+   * A [RunPubList] implementation may be injected for testing
+   */
+  PubPackageMapProvider(this.resourceProvider, this.sdk, [this._runPubList]) {
+    if (_runPubList == null) {
+      _runPubList = _runPubListDefault;
+    }
+  }
 
   @override
   PackageMapInfo computePackageMap(Folder folder) {
     // TODO(paulberry) make this asynchronous so that we can (a) do other
     // analysis while it's in progress, and (b) time out if it takes too long
     // to respond.
-    String executable = sdk.pubExecutable.getAbsolutePath();
     io.ProcessResult result;
     try {
-      result = io.Process.runSync(
-          executable,
-          [PUB_LIST_COMMAND],
-          workingDirectory: folder.path);
+      result = _runPubList(folder);
     } on io.ProcessException catch (exception, stackTrace) {
       AnalysisEngine.instance.logger.logInformation(
           "Error running pub $PUB_LIST_COMMAND\n$exception\n$stackTrace");
     }
     if (result == null || result.exitCode != 0) {
       String exitCode =
           result != null ? 'exit code ${result.exitCode}' : 'null';
       AnalysisEngine.instance.logger.logInformation(
           "pub $PUB_LIST_COMMAND failed: $exitCode");
-      return _error(folder);
+      return computePackageMapError(folder);
     }
     try {
-      return parsePackageMap(result.stdout, folder);
+      PackageMapInfo packageMap =
+          parsePackageMap(JSON.decode(result.stdout), folder);
+      return packageMap;
     } catch (exception, stackTrace) {
       AnalysisEngine.instance.logger.logError(
           "Malformed output from pub $PUB_LIST_COMMAND\n$exception\n$stackTrace");
     }
 
-    return _error(folder);
+    return computePackageMapError(folder);
+  }
+
+  /**
+   * Create a PackageMapInfo object representing an error condition.
+   */
+  PackageMapInfo computePackageMapError(Folder folder) {
+    // Even if an error occurs, we still need to know the dependencies, so that
+    // we'll know when to try running "pub list-package-dirs" again.
+    // Unfortunately, "pub list-package-dirs" doesn't tell us dependencies when
+    // an error occurs, so just assume there is one dependency, "pubspec.lock".
+    List<String> dependencies = <String>[join(folder.path, PUBSPEC_LOCK_NAME)];
+    return new PackageMapInfo(null, dependencies.toSet());
   }
 
   /**
    * Decode the JSON output from pub into a package map.  Paths in the
    * output are considered relative to [folder].
    */
-  PackageMapInfo parsePackageMap(String jsonText, Folder folder) {
+  PackageMapInfo parsePackageMap(Map obj, Folder folder) {
     // The output of pub looks like this:
     // {
     //   "packages": {
     //     "foo": "path/to/foo",
     //     "bar": ["path/to/bar1", "path/to/bar2"],
     //     "myapp": "path/to/myapp",  // self link is included
     //   },
     //   "input_files": [
     //     "path/to/myapp/pubspec.lock"
     //   ]
     // }
     Map<String, List<Folder>> packageMap = new HashMap<String, List<Folder>>();
-    Map obj = JSON.decode(jsonText);
     Map packages = obj['packages'];
     processPaths(String packageName, List paths) {
       List<Folder> folders = <Folder>[];
       for (var path in paths) {
         if (path is String) {
           Resource resource = folder.getChild(path);
           if (resource is Folder) {
             folders.add(resource);
           }
         }
@@ skipping 15 matching lines @@
       for (var path in inputFiles) {
         if (path is String) {
           dependencies.add(folder.canonicalizePath(path));
         }
       }
     }
     return new PackageMapInfo(packageMap, dependencies);
   }
 
   /**
-   * Create a PackageMapInfo object representing an error condition.
+   * Run pub list to determine the packages and input files.
    */
-  PackageMapInfo _error(Folder folder) {
-    // Even if an error occurs, we still need to know the dependencies, so that
-    // we'll know when to try running "pub list-package-dirs" again.
-    // Unfortunately, "pub list-package-dirs" doesn't tell us dependencies when
-    // an error occurs, so just assume there is one dependency, "pubspec.lock".
-    List<String> dependencies = <String>[join(folder.path, PUBSPEC_LOCK_NAME)];
-    return new PackageMapInfo(null, dependencies.toSet());
+  io.ProcessResult _runPubListDefault(Folder folder) {
+    return io.Process.runSync(
+        sdk.pubExecutable.getAbsolutePath(),
+        [PUB_LIST_COMMAND],
+        workingDirectory: folder.path);
   }
 }