Add mirrors tests

test/codegen/lib/mirrors/declarations_type_test.dart

Index: test/codegen/lib/mirrors/declarations_type_test.dart
diff --git a/test/codegen/lib/mirrors/declarations_type_test.dart b/test/codegen/lib/mirrors/declarations_type_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..7cdd20e9a5b49d784027316f2f70968d057e71fa
--- /dev/null
+++ b/test/codegen/lib/mirrors/declarations_type_test.dart
@@ -0,0 +1,30 @@
+// 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.
+
+// Regression test for Issue 14972.
+
+library test.declarations_type;
+
+import 'dart:mirrors';
+import 'package:expect/expect.dart';
+
+class C {}
+
+main() {
+  var classDeclarations = reflectClass(C).declarations;
+  Expect.isTrue(classDeclarations is Map<Symbol, DeclarationMirror>);
+  Expect.isTrue(classDeclarations.values is Iterable<DeclarationMirror>);
+  Expect.isTrue(classDeclarations.values.where((x) => true) is Iterable<DeclarationMirror>);
+  Expect.isFalse(classDeclarations is Map<Symbol, MethodMirror>);
+  Expect.isFalse(classDeclarations.values is Iterable<MethodMirror>);
+  Expect.isFalse(classDeclarations.values.where((x) => true) is Iterable<MethodMirror>);
+
+  var libraryDeclarations = (reflectClass(C).owner as LibraryMirror).declarations;
+  Expect.isTrue(libraryDeclarations is Map<Symbol, DeclarationMirror>);
+  Expect.isTrue(libraryDeclarations.values is Iterable<DeclarationMirror>);
+  Expect.isTrue(libraryDeclarations.values.where((x) => true) is Iterable<DeclarationMirror>);
+  Expect.isFalse(libraryDeclarations is Map<Symbol, ClassMirror>);
+  Expect.isFalse(libraryDeclarations.values is Iterable<ClassMirror>);
+  Expect.isFalse(libraryDeclarations.values.where((x) => true) is Iterable<ClassMirror>);
+}