       calls.should.eql 'ab'
 
     it 'parses, convert and stringify CSS', ->
-      a = (css) -> css.should.be.an.instanceof(Root)
+      a = (css) -> css.should.be.an.instanceof(postcss.Root)
       postcss(a).process('a {}').css.should.have.type('string')
 
     it 'adds map field only on request', ->

SourceMap = require('source-map')
postcss   = require('../lib/postcss')
Result    = require('../lib/result')
Root      = require('../lib/root')

describe 'postcss()', ->


    a = -> 1
    b = -> 2
    postcss(a, b).should.eql { processors: [a, b] }

  describe 'use()', ->

