first cut fuzz test for analysis server

pkg/analysis_server/bin/fuzz.dart

Index: pkg/analysis_server/bin/fuzz.dart
diff --git a/pkg/analysis_server/bin/fuzz.dart b/pkg/analysis_server/bin/fuzz.dart
new file mode 100644
index 0000000000000000000000000000000000000000..8fc71d997bf51a221d91ea65c09d511fc48c29ec
--- /dev/null
+++ b/pkg/analysis_server/bin/fuzz.dart
@@ -0,0 +1,166 @@
+// 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.
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:args/args.dart';
+import 'package:matcher/matcher.dart';
+import 'package:path/path.dart' as path;
+
+import 'fuzz/server_manager.dart';
+
+/**
+ * Start analysis server as a separate process and use the stdio to communicate
+ * with the server.
+ */
+void main(List<String> args) {
+  new _FuzzTest().run(args);
+}
+
+/**
+ * Instances of [_FuzzTest] launch and test an analysis server.
+ * You must specify the location of the Dart SDK and the directory
+ * containing sources to be analyzed.
+ */
+class _FuzzTest {
+
+  //TODO (danrubel) extract common behavior for use in multiple test scenarios
+  //TODO (danrubel) cleanup test to use async/await for better readability
+  // VM flag --enable_async
+
+  static const String DART_SDK_OPTION = 'dart-sdk';
+  static const String HELP_OPTION = 'help';
+
+  File serverSnapshot;
+  Directory appDir;
+
+  /// Parse the arguments and initialize the receiver
+  /// Return `true` if proper arguments were provided
+  bool parseArgs(List<String> args) {
+    ArgParser parser = new ArgParser();
+
+    void error(String errMsg) {
+      stderr.writeln(errMsg);
+      print('');
+      _printUsage(parser);
+      exitCode = 11;
+    }
+
+    parser.addOption(DART_SDK_OPTION, help: '[sdkPath] path to Dart SDK');
+    parser.addFlag(
+        HELP_OPTION,
+        help: 'print this help message without starting analysis',
+        defaultsTo: false,
+        negatable: false);
+
+    ArgResults results;
+    try {
+      results = parser.parse(args);
+    } on FormatException catch (e) {
+      error(e.message);
+      return false;
+    }
+    if (results[HELP_OPTION]) {
+      _printUsage(parser);
+      return false;
+    }
+    String sdkPath = results[DART_SDK_OPTION];
+    if (sdkPath is! String) {
+      error('Missing path to Dart SDK');
+      return false;
+    }
+    Directory sdkDir = new Directory(sdkPath);
+    if (!sdkDir.existsSync()) {
+      error('Specified Dart SDK does not exist: $sdkPath');
+      return false;
+    }
+    if (results.rest.length == 0) {
+      error('Expected directory to analyze');
+      return false;
+    }
+    appDir = new Directory(results.rest[0]);
+    if (!appDir.existsSync()) {

[lukechurch, 2014/09/21 05:36:10]

What is an application directory? Do you mean that we target this at the place
where the pubspec is located? Or just a collection of dart files?

[danrubel, 2014/09/22 18:27:25]

This is the root directory containing the files to be analyzed. This directory
may or may not contain a pubspec and represent a Dart package or could just be a
loose collection of Dart files to be analyzed.

+      error('Specified application directory does not exist: $appDir');
+      return false;
+    }
+    if (results.rest.length > 1) {
+      error('Unexpected arguments after $appDir');
+      return false;
+    }
+    serverSnapshot = new File(
+        path.join(sdkDir.path, 'bin', 'snapshots', 'analysis_server.dart.snapshot'));
+    if (!serverSnapshot.existsSync()) {
+      error('Analysis Server snapshot not found: $serverSnapshot');
+      return false;
+    }
+    return true;
+  }
+
+  /// Main entry point for launching, testing, and shutting down the server
+  void run(List<String> args) {
+    if (!parseArgs(args)) return;
+    ServerManager.start(serverSnapshot.path).then((ServerManager manager) {
+      runZoned(() {
+        test(manager).then(manager.stop).then((_) {
+          expect(manager.errorOccurred, isFalse);
+          print('Test completed successfully');

[lukechurch, 2014/09/21 05:36:11]

I don't really see these as tests as such, but more as a tool that can be used
to locate errors. I am up or being persuaded that they should be run and
structured as tests.

[danrubel, 2014/09/22 18:27:25]

I'm happy to refactor in subsequent CLs as we/I better understand the
requirements.

+        });
+      }, onError: (error, stack) {
+        stderr.writeln(error);

[lukechurch, 2014/09/21 05:36:11]

From experience of writing a couple of these things before, using stderr makes
doing post analysis of the results more complicated than it really needs to be.
I've been inclined to route all the data into a seperate log file and dumping
tool status information to stdout and very little to stderr.

This can be finessed going forwards. 

[danrubel, 2014/09/22 18:27:25]

Fair enough. Will refactor in subsequent CLs.

+        print(stack);
+        exitCode = 12;

[lukechurch, 2014/09/21 05:36:11]

Why 12?

[danrubel, 2014/09/22 18:27:25]

Just picking a random exit code that's not 1 and unique within this codebase.
Don't know if that's important or if I should just return exitCode = 1.

+        manager.stop();
+      });
+    });
+  }
+
+  /// Use manager to exercise the analysis server
+  Future test(ServerManager manager) {
+
+    // perform initial analysis
+    return manager.analyze(appDir).then((AnalysisResults analysisResults) {
+      print(
+          'Found ${analysisResults.errorCount} errors,'
+              ' ${analysisResults.warningCount} warnings,'
+              ' and ${analysisResults.hintCount} hints in ${analysisResults.elapsed}');
+
+      // edit a method body
+      return manager.openFileNamed(
+          'domain_completion.dart').then((Editor editor) {
+        return editor.moveAfter('Response processRequest(Request request) {');
+      }).then((Editor editor) {
+        return editor.replace(0, '\nOb');
+      }).then((Editor editor) {
+
+        // request code completion and assert results
+        return editor.getSuggestions().then((List<CompletionResults> list) {
+          expect(list, isNotNull);
+          expect(list.length, equals(0));

[lukechurch, 2014/09/21 05:36:11]

I don't follow this. Why would the list has of length zero? If it is zero, why
do we then iterate over it?

[danrubel, 2014/09/22 18:27:25]

I'm getting an exception after text replacement but before this point in the
code so I set this to zero so that this would fail when I'm actually returning
real data. I want to land this CL and iterate.

+          list.forEach((CompletionResults results) {
+            print('${results.elapsed} received ${results.suggestionCount} suggestions');
+          });
+          return editor;
+        });
+
+      }).then((Editor editor) {
+        print('tests complete');
+      });
+    });
+  }
+
+  void _printAnalysisSummary(AnalysisResults results) {
+    print(
+        'Found ${results.errorCount} errors, ${results.warningCount} warnings,'
+            ' and ${results.hintCount} hints in $results.elapsed');
+  }
+
+  /// Print information about how to use the server.
+  void _printUsage(ArgParser parser) {
+    print('Usage: analyzer [flags] <application_directory>');
+    print('');
+    print('Supported flags are:');
+    print(parser.getUsage());
+  }
+}