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;

[Emily Fortuna, 2014/04/16 22:13:40]

I hate single letter names for these, but since it's a test I'll let it slide...

[kevmoo, 2014/04/17 00:01:19]

'p' is a pretty common convention, at least for Bob/Nathan code.

+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('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.json');
+      var dartCoreJson = new File(path).readAsStringSync();
+
+      var testLibBar = JSON.decode(dartCoreJson) as Map<String, dynamic>;
+
+      //
+      // Validate function doc references
+      //
+      var functionDef =
+          testLibBar['functions']['methods']['positionalDefaultValues'] as Map<String,

[Emily Fortuna, 2014/04/16 22:13:40]

80 char

[kevmoo, 2014/04/17 00:01:19]

Done.

+          dynamic>;
+
+      var params = functionDef['parameters'] as Map<String, dynamic>;
+
+      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\""
+};