pkg/docgen: support better const rendering of String, List, and empty Map

pkg/docgen/test/constant_argument_test.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 docgen.test.typedef;
 
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/descriptor.dart' as d;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import 'util.dart';
 import '../lib/docgen.dart' as dg;
 
 void main() {
 
   setUp(() {
     scheduleTempDir();
   });
 
-  test('typedef gen', () {
+  test('argument default values', () {
     schedule(() {
       var codeDir = getMultiLibraryCodePath();
       expect(FileSystemEntity.isDirectorySync(codeDir), isTrue);
       return dg.docgen([codeDir], out: p.join(d.defaultRoot, 'docs'));
     });
 
     schedule(() {
-      var path = p.join(d.defaultRoot, 'docs', 'test_lib-bar.json');
+      var path = p.join(d.defaultRoot, 'docs', 'test_lib.json');
       var dartCoreJson = new File(path).readAsStringSync();
 
       var testLibBar = JSON.decode(dartCoreJson) as Map<String, dynamic>;
 
       //
       // Validate function doc references
       //
-      var generateFoo = testLibBar['functions']['methods']['generateFoo']
+      var functionDef =
+          testLibBar['functions']['methods']['positionalDefaultValues']
           as Map<String, dynamic>;
 
-      expect(generateFoo['comment'], '<p><a>test_lib-bar.generateFoo.input</a> '
-          'is of type <a>test_lib-bar.C</a> returns an <a>test_lib.A</a>.</p>');
+      var params = functionDef['parameters'] as Map<String, dynamic>;
 
-      var classes = testLibBar['classes'] as Map<String, dynamic>;
-
-      expect(classes, hasLength(3));
-
-      expect(classes['class'], isList);
-      expect(classes['error'], isList);
-
-      var typeDefs = classes['typedef'] as Map<String, dynamic>;
-      var comparator = typeDefs['AnATransformer'] as Map<String, dynamic>;
-
-      var expectedPreview = '<p>Processes a [C] instance for testing.</p>';
-
-      expect(comparator['preview'], expectedPreview);
-
-      var expectedComment = expectedPreview + '\n'
-          '<p>To eliminate import warnings for [A] and to test typedefs.</p>';
-
-      expect(comparator['comment'], expectedComment);
+      var vals = {};
+      params.forEach((paramName, paramHash) {
+        expect(_PARAM_VALUES, contains(paramName));
+        expect(paramHash['value'], _PARAM_VALUES[paramName],
+            reason: 'Value for $paramName should match expected');
+      });
     });
   });
 }
+
+final _PARAM_VALUES = {
+  "boolConst": "true",
+  "intConst": "42",
+  "listConst": '[true, 42, "Shanna", null, 3.14, []]',
+  "mapConst": startsWith("Map"),
+  "emptyMap": '{}',
+  "stringConst": "\"Shanna\""
+};