node.js - Node mocha array should contain an element -

i want simple assertion of like

knownarray.should.include('known value') 

the array correct, can't figure out proper assertion use check whether array has value (the index doesn't matter). tried should.contain both of these throw error object #<assertion> has no method 'contain' (or 'include')

how can check array contains element using should?

should.js has containeql method. in case:

knownarray.should.containeql('known value'); 

the methods include, includes , contain find in chai.js.