rspecによるｺﾝﾄﾛｰﾗ起動ﾃｽﾄ時にｴﾗｰ

前提・実現したいこと

ここに質問の内容を詳しく書いてください。
ruby on railsのテスト実装中に以下のエラーメッセージが発生致しました。
※ruby on rails初心者です。
spec/controllers/messages_controller_spec.rb
Ruby 2.5.1
Rails 5.0.7.2

発生している問題・エラーメッセージ

1) #create log in can save count up message
     Failure/Error: login user
     
     NameError:
       undefined local variable or method `user' for #<RSpec::ExampleGroups::Create::LogIn::CanSave:0x00007f8d7443d7b8>
       Did you mean?  super
     # ./spec/controllers/messages_controller_spec.rb:47:in `block (3 levels) in <top (required)>'

  2) #create log in can save redirects to group_messages_path
     Failure/Error: login user
     
     NameError:
       undefined local variable or method `user' for #<RSpec::ExampleGroups::Create::LogIn::CanSave:0x00007f8d74446728>
       Did you mean?  super
     # ./spec/controllers/messages_controller_spec.rb:47:in `block (3 levels) in <top (required)>'

  3) #create log in can not save does not count up
     Failure/Error: login user
     
     NameError:
       undefined local variable or method `user' for #<RSpec::ExampleGroups::Create::LogIn::CanNotSave:0x00007f8d7444f198>
       Did you mean?  super
     # ./spec/controllers/messages_controller_spec.rb:47:in `block (3 levels) in <top (required)>'

  4) #create log in can not save renders index
     Failure/Error: login user
     
     NameError:
       undefined local variable or method `user' for #<RSpec::ExampleGroups::Create::LogIn::CanNotSave:0x00007f8d7369efd0>
       Did you mean?  super
     # ./spec/controllers/messages_controller_spec.rb:47:in `block (3 levels) in <top (required)>'

  5) #create not log in redirects to new_user_session_path
     Failure/Error: let(:params) { { group_id: group.id, user_id: user.id, message: attributes_for(:message) } }
     
     NameError:
       undefined local variable or method `group' for #<RSpec::ExampleGroups::Create::NotLogIn:0x00007f8d75174b70>

該当のソースコード


require 'rails_helper'

describe MessagesController do
  let(:group) { create(:group) }
  let(:user) { create(:user) }

  describe '#index' do

    context 'log in' do
      before do
        login user
        get :index, params: { group_id: group.id }
      end

      it 'assigns @message' do
        expect(assigns(:message)).to be_a_new(Message)
      end

      it 'assigns @group' do
        expect(assigns(:group)).to eq group
      end

      it 'redners index' do
        expect(response).to render_template :index
      end
    end

    context 'not log in' do
      before do
        get :index, params: { group_id: group.id }
      end

      it 'redirects to new_user_session_path' do
        expect(response).to redirect_to(new_user_session_path)
      end
    end
  end
end



describe '#create' do
    let(:params) { { group_id: group.id, user_id: user.id, message: attributes_for(:message) } }

    context 'log in' do
      before do
        login user
      end

      context 'can save' do
        subject {
          post :create,
          params: params
        }

        it 'count up message' do
          expect{ subject }.to change(Message, :count).by(1)
        end

        it 'redirects to group_messages_path' do
          subject
          expect(response).to redirect_to(group_messages_path(group))
        end
      end

      context 'can not save' do
        let(:invalid_params) { { group_id: group.id, user_id: user.id, message: attributes_for(:message, content: nil, image: nil) } }

        subject {
          post :create,
          params: invalid_params
        }

        it 'does not count up' do
          expect{ subject }.not_to change(Message, :count)
        end

        it 'renders index' do
          subject
          expect(response).to render_template :index
        end
      end
    end

    context 'not log in' do

      it 'redirects to new_user_session_path' do
        post :create, params: params
        expect(response).to redirect_to(new_user_session_path)
      end
    end
  end

試したこと

1)〜4)の原因は
undefined local variable or method `user' for #RSpec::ExampleGroups::Create::LogIn::CanSave:0x00007f8d74446728
Did you mean? super
5) は 1)〜4)の'user'部分が'group'となっております。
変数が定義されていないということで、userとgroupコントローラーを確認致しました。
※以下
=>users_controller.rb
class UsersController < ApplicationController
def edit
end