What does that line of code do?
assigns(:articles).should eq([article])
in the following rspec
describe \"GET #index\" do
assigns
relates to the instance variables created within a controller action (and assigned to the view).
to answer your remark in comments, I guess that:
1) your index action looks like @articles = Articles.all
(I hope you use pagination though)
2) prior to the spec block above, you have one article created in db (or I hope you stub db queries in db)
1 + 2 => @articles
should contain one article, that's your spec expectation