add specs of gist controller

spec/controllers/gists_controller_spec.rb

@@ -1,5 +1,49 @@
 require 'spec_helper'
 
 describe GistsController do
+  describe "GET show" do
+    let(:gist_object) {FactoryGirl.create(:gist)}
 
+    context "with sign in" do
+      let!(:tag) do
+        tag = Tag.create!(name: "tag", user_id: gist_object.user.id, gist_id: gist_object.id)
+        get :show, {id: gist_object.id}, {user: gist_object.user.id}
+        tag
+      end
+
+      it "return http success" do
+        expect(response).to be_success
+      end
+
+      it "assigns current_user as user" do
+        expect(assigns(:current_user)).to eq(gist_object.user)
+      end
+
+      it "assigns tags as tag" do
+        expect(assigns(:tags)).to eq([tag.name])
+      end
+    end
+
+    context "with not sign in" do
+      it "return http 404 if not sign in" do
+        get :show, {id: gist_object.id}
+        expect(response.status).to eq(404)
+      end
+    end
+
+    context "with bad request" do
+      it "return http 404 if not exists gist" do
+        Gist.should_receive(:find).and_raise(ActiveRecord::RecordNotFound)
+        get :show, {id: gist_object.id}, {user: gist_object.user.id}
+        expect(response.status).to eq(404)
+      end
+
+      it "return http 404 if othor user's private gist" do
+        g = FactoryGirl.create(:gist)
+        g.update_attributes!(public_gist: false)
+        get :show, {id: g.id}, {user: gist_object.user.id}
+        expect(response.status).to eq(404)
+      end
+    end
+  end
 end