diff --git a/spec/controllers/application_controller_spec.rb b/spec/controllers/application_controller_spec.rb
index 44830e12b2..1b209feb50 100644
--- a/spec/controllers/application_controller_spec.rb
+++ b/spec/controllers/application_controller_spec.rb
@@ -2,7 +2,69 @@
 
 require 'rails_helper'
 
-describe ApplicationController do
+describe ApplicationController, type: :controller do
+  controller do
+    def success
+      head 200
+    end
+
+    def routing_error
+      raise ActionController::RoutingError, ''
+    end
+
+    def record_not_found
+      raise ActiveRecord::RecordNotFound, ''
+    end
+
+    def invalid_authenticity_token
+      raise ActionController::InvalidAuthenticityToken, ''
+    end
+  end
+
+  shared_examples 'respond_with_error' do |code|
+    it "returns http #{code} for any" do
+      subject
+      expect(response).to have_http_status(code)
+    end
+
+    it "returns http #{code} for http" do
+      subject
+      expect(response).to have_http_status(code)
+    end
+
+    it "renders template for http" do
+      is_expected.to render_template("errors/#{code}", layout: 'error')
+    end
+  end
+
+  it "does not force ssl if LOCAL_HTTPS is not 'true'" do
+    routes.draw { get 'success' => 'anonymous#success' }
+    ENV['LOCAL_HTTPS'] = ''
+    allow(Rails.env).to receive(:production?).and_return(true)
+    get 'success'
+    expect(response).to have_http_status(:success)
+  end
+
+  it "forces ssl if LOCAL_HTTPS is 'true'" do
+    routes.draw { get 'success' => 'anonymous#success' }
+    ENV['LOCAL_HTTPS'] = 'true'
+    allow(Rails.env).to receive(:production?).and_return(true)
+    get 'success'
+    expect(response).to redirect_to('https://test.host/success')
+  end
+
+  describe 'helper_method :current_account' do
+    it 'returns nil if not signed in' do
+      expect(controller.view_context.current_account).to be_nil
+    end
+
+    it 'returns account if signed in' do
+      account = Fabricate(:account)
+      sign_in(Fabricate(:user, account: account))
+      expect(controller.view_context.current_account).to eq account
+    end
+  end
+
   describe 'helper_method :single_user_mode?' do
     it 'returns false if it is in single_user_mode but there is no account' do
       allow(Rails.configuration.x).to receive(:single_user_mode).and_return(true)
@@ -21,4 +83,207 @@ describe ApplicationController do
       expect(controller.view_context.single_user_mode?).to eq true
     end
   end
+
+  context 'ActionController::RoutingError' do
+    subject do
+      routes.draw { get 'routing_error' => 'anonymous#routing_error' }
+      get 'routing_error'
+    end
+
+    include_examples 'respond_with_error', 404
+  end
+
+  context 'ActiveRecord::RecordNotFound' do
+    subject do
+      routes.draw { get 'record_not_found' => 'anonymous#record_not_found' }
+      get 'record_not_found'
+    end
+
+    include_examples 'respond_with_error', 404
+  end
+
+  context 'ActionController::InvalidAuthenticityToken' do
+    subject do
+      routes.draw { get 'invalid_authenticity_token' => 'anonymous#invalid_authenticity_token' }
+      get 'invalid_authenticity_token'
+    end
+
+    include_examples 'respond_with_error', 422
+  end
+
+  describe 'before_action :store_current_location' do
+    it 'stores location for user if it is not devise controller' do
+      routes.draw { get 'success' => 'anonymous#success' }
+      get 'success'
+      expect(controller.stored_location_for(:user)).to eq '/success'
+    end
+
+    context do
+      controller Devise::SessionsController do
+      end
+
+      it 'does not store location for user if it is devise controller' do
+        @request.env["devise.mapping"] = Devise.mappings[:user]
+        get 'create'
+        expect(controller.stored_location_for(:user)).to be_nil
+      end
+    end
+  end
+
+  describe 'before_action :check_suspension' do
+    before do
+      routes.draw { get 'success' => 'anonymous#success' }
+    end
+
+    it 'does nothing if not signed in' do
+      get 'success'
+      expect(response).to have_http_status(:success)
+    end
+
+    it 'does nothing if user who signed in is not suspended' do
+      sign_in(Fabricate(:user, account: Fabricate(:account, suspended: false)))
+      get 'success'
+      expect(response).to have_http_status(:success)
+    end
+
+    it 'returns http 403 if user who signed in is suspended' do
+      sign_in(Fabricate(:user, account: Fabricate(:account, suspended: true)))
+      get 'success'
+      expect(response).to have_http_status(403)
+    end
+  end
+
+  describe 'raise_not_found' do
+    it 'raises error' do
+      controller.params[:unmatched_route] = 'unmatched'
+      expect{ controller.raise_not_found }.to raise_error(ActionController::RoutingError, 'No route matches unmatched')
+    end
+  end
+
+  describe 'require_admin!' do
+    controller do
+      before_action :require_admin!
+
+      def sucesss
+        head 200
+      end
+    end
+
+    before do
+      routes.draw { get 'sucesss' => 'anonymous#sucesss' }
+    end
+
+    it 'redirects to root path if current user is not admin' do
+      sign_in(Fabricate(:user, admin: false))
+      get 'sucesss'
+      expect(response).to redirect_to('/')
+    end
+
+    it 'does nothing if current user is admin' do
+      sign_in(Fabricate(:user, admin: true))
+      get 'sucesss'
+      expect(response).to have_http_status(200)
+    end
+  end
+
+  describe 'forbidden' do
+    controller do
+      def route_forbidden
+        forbidden
+      end
+    end
+
+    subject do
+      routes.draw { get 'route_forbidden' => 'anonymous#route_forbidden' }
+      get 'route_forbidden'
+    end
+
+    include_examples 'respond_with_error', 403
+  end
+
+  describe 'not_found' do
+    controller do
+      def route_not_found
+        not_found
+      end
+    end
+
+    subject do
+      routes.draw { get 'route_not_found' => 'anonymous#route_not_found' }
+      get 'route_not_found'
+    end
+
+    include_examples 'respond_with_error', 404
+  end
+
+  describe 'gone' do
+    controller do
+      def route_gone
+        gone
+      end
+    end
+
+    subject do
+      routes.draw { get 'route_gone' => 'anonymous#route_gone' }
+      get 'route_gone'
+    end
+
+    include_examples 'respond_with_error', 410
+  end
+
+  describe 'unprocessable_entity' do
+    controller do
+      def route_unprocessable_entity
+        unprocessable_entity
+      end
+    end
+
+    subject do
+      routes.draw { get 'route_unprocessable_entity' => 'anonymous#route_unprocessable_entity' }
+      get 'route_unprocessable_entity'
+    end
+
+    include_examples 'respond_with_error', 422
+  end
+
+  describe 'cache_collection' do
+    class C < ApplicationController
+      public :cache_collection
+    end
+
+    shared_examples 'receives :with_includes' do |fabricator, klass|
+      it 'uses raw if it is not an ActiveRecord::Relation' do
+        record = Fabricate(fabricator)
+        expect(C.new.cache_collection([record], klass)).to match_array([record])
+      end
+    end
+
+    shared_examples 'cacheable' do |fabricator, klass|
+      include_examples 'receives :with_includes', fabricator, klass
+
+      it 'calls cache_ids of raw if it is an ActiveRecord::Relation' do
+        record = Fabricate(fabricator)
+        relation = klass.none
+        allow(relation).to receive(:cache_ids).and_return([record])
+        expect(C.new.cache_collection(relation, klass)).to match_array([record])
+      end
+    end
+
+    it 'returns raw unless class responds to :with_includes' do
+      raw = Object.new
+      expect(C.new.cache_collection(raw, Object)).to eq raw
+    end
+
+    context 'Notification' do
+      include_examples 'cacheable', :notification, Notification
+    end
+
+    context 'Status' do
+      include_examples 'cacheable', :status, Status
+    end
+
+    context 'StreamEntry' do
+      include_examples 'receives :with_includes', :stream_entry, StreamEntry
+    end
+  end
 end
diff --git a/spec/fabricators/stream_entry_fabricator.rb b/spec/fabricators/stream_entry_fabricator.rb
new file mode 100644
index 0000000000..f33822c7c5
--- /dev/null
+++ b/spec/fabricators/stream_entry_fabricator.rb
@@ -0,0 +1,5 @@
+Fabricator(:stream_entry) do
+  account
+  activity { Fabricate(:status) }
+  hidden { [true, false].sample }
+end