#97 test case fix

Author: 刘祺

test.js

@@ -7,6 +7,7 @@ var sourceMaps = require('gulp-sourcemaps')
 var postcss = require('./index')
 var proxyquire = require('proxyquire')
 var sinon = require('sinon')
+var path = require('path')
 
 it('should pass file when it isNull()', function (cb) {
   var stream = postcss([ doubler ])
@@ -261,7 +262,7 @@ describe('PostCSS Guidelines', function () {
     var stream = postcss([ doubler ])
     var cssPath = __dirname + '/src/fixture.css'
     function Warning (msg) {
-      this.toSting = function () {
+      this.toString = function () {
         return msg
       }
     }
@@ -275,7 +276,7 @@ describe('PostCSS Guidelines', function () {
     }))
 
     stream.on('data', function () {
-      gutil.log.calledWith('gulp-postcss:', '/src/fixture.css\nmsg1\nmsg2')
+      assert(gutil.log.calledWith('gulp-postcss:', 'src' +  path.sep + 'fixture.css\nmsg1\nmsg2'))
       cb()
     })