message.yaml test - first cut

pkg/front_end/test/fasta/messages_test.dart

+// Copyright (c) 2017, 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:io';
+
+import 'package:yaml/yaml.dart' show loadYaml;
+
+main(List<String> arguments) async {
+  Uri messagesFile = Platform.script.resolve("../../messages.yaml");

[ahe, 2017/09/01 12:27:55]

I think this is more reliable:

Uri.base.resolve("pkg/front_end/messages.yaml")

+  Map yaml = loadYaml(await new File.fromUri(messagesFile).readAsStringSync());

[ahe, 2017/09/01 12:27:54]

Remove Sync.

+
+  int untestedExampleCount = 0;
+  int missingExamplesCount = 0;
+  int missingAnalyzerCode = 0;
+  int missingDart2jsCode = 0;
+  List<String> keys = yaml.keys.toList()..sort();
+  for (String name in keys) {
+    var description = yaml[name];
+    while (description is String) {
+      description = yaml[description];
+    }
+    Map map = description;
+
+    int localUntestedExampleCount = countExamples(map, name, 'bytes');
+    localUntestedExampleCount += countExamples(map, name, 'declaration');
+    localUntestedExampleCount += countExamples(map, name, 'expression');
+    localUntestedExampleCount += countExamples(map, name, 'script');
+    localUntestedExampleCount += countExamples(map, name, 'statement');
+    if (localUntestedExampleCount == 0) ++missingExamplesCount;
+    untestedExampleCount += localUntestedExampleCount;
+
+    if (map['analyzerCode'] == null) ++missingAnalyzerCode;
+    if (map['dart2jsCode'] == null) ++missingDart2jsCode;
+  }
+
+  print('$untestedExampleCount examples not tested');
+  print('$missingExamplesCount error codes missing examples');
+  print('$missingAnalyzerCode error codes missing analyzer code');
+  print('$missingDart2jsCode error codes missing dart2js code');

[ahe, 2017/09/01 12:27:54]

We don't need dart2js error codes for all errors. We only need them for the ones
that are generated by the parser.

+
+  // TODO(danrubel): Update this test to assert each count == 0.
+  // Allow them to be non-zero until messages.yaml has been updated.
+  return untestedExampleCount == 0 ||
+          missingExamplesCount == 0 ||
+          missingAnalyzerCode == 0 ||
+          missingDart2jsCode == 0
+      ? 1
+      : 0;

[ahe, 2017/09/01 12:27:54]

In Dart, main's return value is ignored. So how about just deleting these lines?

+}
+
+int countExamples(Map map, String name, String key) {
+  var example = map[key];
+  if (example == null) return 0;
+  if (example is String) return 1;
+  if (example is List) return example.length;
+  if (example is Map) return example.length;
+
+  throw 'Unknown value for $name $key --> ${example.runtimeType}\n  $example';
+}