Implements the HasFilters controller concern

app/controllers/concerns/has_filters.rb

@@ -0,0 +1,13 @@
+module HasFilters
+  extend ActiveSupport::Concern
+
+  class_methods do
+    def has_filters(valid_filters, *args)
+      before_filter(*args) do
+        @valid_filters = valid_filters
+        @current_filter = params[:filter]
+        @current_filter = @valid_filters.first unless @valid_filters.include?(@current_filter)
+      end
+    end
+  end
+end

spec/controllers/concerns/has_filters_spec.rb

@@ -0,0 +1,37 @@
+require 'rails_helper'
+
+describe 'HasFilters' do
+
+  class FakeController < ActionController::Base; end
+
+  controller(FakeController) do
+    include HasFilters
+    has_filters ['all', 'pending', 'reviewed'], only: :index
+
+    def index
+      render text: "#{@current_filter} (#{@valid_filters.join(' ')})"
+    end
+  end
+
+  it "has the valid filters set up" do
+    get :index
+    expect(response.body).to eq('all (all pending reviewed)')
+  end
+
+  describe "the current filter" do
+    it "defaults to the first one on the list" do
+      get :index
+      expect(response.body).to eq('all (all pending reviewed)')
+    end
+
+    it "can be changed by the filter param" do
+      get :index, filter: 'pending'
+      expect(response.body).to eq('pending (all pending reviewed)')
+    end
+
+    it "defaults to the first one on the list if given a bogus filter" do
+      get :index, filter: 'foobar'
+      expect(response.body).to eq('all (all pending reviewed)')
+    end
+  end
+end