RSpec shared examples with template methods

It’s pretty common to have multiple tests that are nearly the same.

In one app, we support bidding on both online and hammer auctions (auctions with people physically present). They’re separate controllers but with a lot of shared code and behavior.

We want to test both, but we’d rather not write two almost identical tests if we can help it.

So we’ve been using RSpec shared examples, with the template method patternto account for the differences, and we like it.

Here’s a simplified example:

spec/request/online_bidding_spec.rb

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require "spec_helper" require "support/shared_examples/bidding" describe "Bidding online" do include_examples :bidding let(:auction) { FactoryGirl.create(:online_auction) } def auction_path online_auction_path(auction) end end

spec/request/hammer_bidding_spec.rb

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require "spec_helper" require "support/shared_examples/bidding" describe "Bidding at hammer auction" do include_examples :bidding let(:auction) { FactoryGirl.create(:hammer_auction) } def auction_path hammer_auction_path(auction) end end

spec/support/shared_examples/bidding.rb

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shared_examples :bidding do it "lets you bid when logged in" do log_in # Implemented somewhere else. visit auction_path place_bid bid_should_be_accepted end it "doesn't let you bid when not logged in" do visit item_path place_bid bid_should_be_rejected end def auction_path raise "Implement me." end def place_bid fill_in "Bid", with: 123 click_button "Place bid" end def bid_should_be_accepted page.should have_content("OK! :)") end def bid_should_be_rejected page.should have_content("NO! :(") end end

The only template method here is auction_path . The shared example makes sure, by raising, that it’s overridden in your concrete specs.