style: rubocopの指摘箇所を修正 (#66)

RSpec/ExampleLengthとRSpec/MultipleExpectationsを無効にした

.rubocop.yml

@@ -11,9 +11,7 @@ inherit_gem:
     - "config/rails.yml"
 
 RSpec/ExampleLength:
-  Exclude:
-    - spec/system/*
+  Enabled: false
 
 RSpec/MultipleExpectations:
-  Exclude:
-    - spec/system/*
+  Enabled: false

app/models/user.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class User < ApplicationRecord
   validates :provider, presence: true
   validates :uid, presence: true, uniqueness: { scope: :provider }

spec/factories/users.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 FactoryBot.define do
   factory :user do
     provider { 'github' }

spec/models/user_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 
 RSpec.describe User, type: :model do
@@ -75,12 +77,12 @@
     context 'when user does not exist' do
       it 'creates a new user' do
         expect do
-          User.find_or_create_from_auth_hash!(auth_hash)
-        end.to change(User, :count).by(1)
+          described_class.find_or_create_from_auth_hash!(auth_hash)
+        end.to change(described_class, :count).by(1)
       end
 
       it 'returns the created user' do
-        user = User.find_or_create_from_auth_hash!(auth_hash)
+        user = described_class.find_or_create_from_auth_hash!(auth_hash)
         expect(user).to have_attributes(
           provider: 'github',
           uid: '0001',
@@ -91,16 +93,16 @@
     end
 
     context 'when user already exists' do
-      let!(:existing_user) { FactoryBot.create(:user) }
+      before { FactoryBot.create(:user) }
 
       it 'does not create a new user' do
         expect do
-          User.find_or_create_from_auth_hash!(auth_hash)
-        end.not_to change(User, :count)
+          described_class.find_or_create_from_auth_hash!(auth_hash)
+        end.not_to change(described_class, :count)
       end
 
       it 'returns the existing user' do
-        user = User.find_or_create_from_auth_hash!(auth_hash)
+        user = described_class.find_or_create_from_auth_hash!(auth_hash)
         expect(user).to have_attributes(
           provider: 'github',
           uid: '0001',