pkg/csslib: use pkg/test and allow latest version of logging pkg

test/testing.dart

 // Copyright (c) 2012, 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.
 
 /** Common definitions used for setting up the test environment. */
 library testing;
 
 import 'package:csslib/parser.dart';
 import 'package:csslib/visitor.dart';
 import 'package:csslib/src/messages.dart';
 import 'package:csslib/src/options.dart';
 
 export 'package:csslib/src/options.dart';
 
 const simpleOptionsWithCheckedAndWarningsAsErrors = const PreprocessorOptions(
     useColors: false,
     checked: true,
     warningsAsErrors: true,
     inputFile: 'memory');
 
 const simpleOptions =
     const PreprocessorOptions(useColors: false, inputFile: 'memory');
 
 const options = const PreprocessorOptions(
     useColors: false, warningsAsErrors: true, inputFile: 'memory');
 
-void useMockMessages() {
-  messages = new Messages(printHandler: (message) {});
-}
-
 /**
  * Spin-up CSS parser in checked mode to detect any problematic CSS.  Normally,
  * CSS will allow any property/value pairs regardless of validity; all of our
  * tests (by default) will ensure that the CSS is really valid.
  */
 StyleSheet parseCss(String cssInput,
     {List<Message> errors, PreprocessorOptions opts}) => parse(cssInput,
         errors: errors,
         options: opts == null
             ? simpleOptionsWithCheckedAndWarningsAsErrors
@@ skipping 40 matching lines @@
   walkTree(ss);
   return (_emitCss..visitTree(ss, pretty: false)).toString();
 }
 
 /** Walks the style sheet tree does nothing; insures the basic walker works. */
 void walkTree(StyleSheet ss) {
   _cssVisitor..visitTree(ss);
 }
 
 String dumpTree(StyleSheet ss) => treeToDebugString(ss);