expose option to not parse function bodies when calling parseCompilationUnit

pkg/analyzer/test/parse_compilation_unit_test.dart

 // Copyright (c) 2013, 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 test.parse.compilation.unit;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:unittest/unittest.dart';
 
 void main() {
@@ skipping 14 matching lines @@
   });
 
   test("defaults to '<unknown source>' if no name is provided", () {
     expect(() {
       parseCompilationUnit("void main() => print('Hello, world!')");
     }, throwsA(predicate((error) {
       return error is AnalyzerErrorGroup &&
           error.toString().contains("Error in <unknown source>: Expected to find ';'");
     })));
   });
+
+  test("allows you to specify whether or not to parse function bodies", () {
+    var unit = parseCompilationUnit(
+        "void main() => print('Hello, world!');", parseFunctionBodies: false);
+    expect(unit.toString(), equals("void main() ;"));
+  });
 }