指摘していただいた部分を修正しました。

.gitignore

@@ -40,3 +40,6 @@ yarn-debug.log*
 .yarn-integrity
 
 /config/credentials/production.key
+
+.DS_Store
+vendor/bundle/

.node-version

@@ -0,0 +1 @@
+16.16.0

Gemfile

@@ -46,6 +46,9 @@ group :development, :test do
   gem 'byebug', platforms: %i[mri mingw x64_mingw]
   gem 'rb-readline'
   gem 'rspec-rails'
+  gem 'capybara', '~> 3.23'
+  gem 'selenium-webdriver', '4.9.0'
+  gem 'webdrivers'
 end
 
 group :development do

Gemfile.lock

@@ -106,6 +106,15 @@ GEM
       msgpack (~> 1.0)
     builder (3.2.4)
     byebug (11.1.3)
+    capybara (3.39.2)
+      addressable
+      matrix
+      mini_mime (>= 0.1.3)
+      nokogiri (~> 1.8)
+      rack (>= 1.6.0)
+      rack-test (>= 0.6.3)
+      regexp_parser (>= 1.5, < 3.0)
+      xpath (~> 3.2)
     concurrent-ruby (1.1.9)
     crass (1.0.6)
     diff-lcs (1.4.4)
@@ -173,6 +182,7 @@ GEM
     mail (2.7.1)
       mini_mime (>= 0.1.1)
     marcel (1.0.2)
+    matrix (0.4.2)
     method_source (1.0.0)
     mini_mime (1.1.2)
     minitest (5.14.4)
@@ -181,6 +191,8 @@ GEM
     multi_xml (0.6.0)
     multipart-post (2.1.1)
     nio4r (2.5.8)
+    nokogiri (1.12.5-arm64-darwin)
+      racc (~> 1.4)
     nokogiri (1.12.5-x86_64-darwin)
       racc (~> 1.4)
     nokogiri (1.12.5-x86_64-linux)
@@ -284,6 +296,7 @@ GEM
       rubocop (>= 1.7.0, < 2.0)
     ruby-progressbar (1.11.0)
     ruby2_keywords (0.0.5)
+    rubyzip (2.3.2)
     sass-rails (6.0.0)
       sassc-rails (~> 2.1, >= 2.1.1)
     sassc (2.4.0)
@@ -294,6 +307,10 @@ GEM
       sprockets (> 3.0)
       sprockets-rails
       tilt
+    selenium-webdriver (4.9.0)
+      rexml (~> 3.2, >= 3.2.5)
+      rubyzip (>= 1.2.2, < 3.0)
+      websocket (~> 1.0)
     semantic_range (3.0.0)
     sorcery (0.16.1)
       bcrypt (~> 3.1)
@@ -318,24 +335,33 @@ GEM
       activemodel (>= 6.0.0)
       bindex (>= 0.4.0)
       railties (>= 6.0.0)
+    webdrivers (5.3.1)
+      nokogiri (~> 1.6)
+      rubyzip (>= 1.3.0)
+      selenium-webdriver (~> 4.0, < 4.11)
     webpacker (5.4.3)
       activesupport (>= 5.2)
       rack-proxy (>= 0.6.1)
       railties (>= 5.2)
       semantic_range (>= 2.3.0)
+    websocket (1.2.10)
     websocket-driver (0.7.5)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
+    xpath (3.2.0)
+      nokogiri (~> 1.8)
     zeitwerk (2.5.1)
 
 PLATFORMS
+  arm64-darwin-22
   x86_64-darwin-19
   x86_64-linux
 
 DEPENDENCIES
   aws-sdk-s3
   bootsnap (>= 1.4.4)
   byebug
+  capybara (~> 3.23)
   draper
   enum_help
   factory_bot_rails
@@ -356,11 +382,13 @@ DEPENDENCIES
   rubocop
   rubocop-rails
   sass-rails (>= 6)
+  selenium-webdriver (= 4.9.0)
   sorcery
   spring
   sqlite3 (~> 1.4)
   tzinfo-data
   web-console (>= 4.1.0)
+  webdrivers
   webpacker (~> 5.0)
 
 RUBY VERSION

README.md

@@ -2,10 +2,24 @@
 
 ## 環境構築
 ```
-$ bundle install
+$ bundle install --without=production
 $ bin/rails db:setup
 $ yarn install
+$ bin/webpack
 $ bin/rails s
 ```
 
 ## 事業をエンジニアリングしよう提案編の回答は以下に記述してください
+```
+選択した事業側の課題
+直近一年間で、2回以上もくもく会に参加してくれた人は利用者全体の1%のみ。もくもく会で気の合う仲間を見つけられなかったのではないか？
+
+提案内容
+・もくもく会にタグ(Ruby, Rails, PHP, iOS, 駆け出しエンジニア etc)を設定 & 絞り込みができるようにする
+→ 自分の学習している言語を見つけやすくする。また、人気のタグを表示することで、ユーザーは他の・ユーザープロフィールに、ユーザーのタグ情報を追加する。
+→　人々がどのようなトピックに関心を持っているかを知り、共通の興味を持つ仲間を見つけやすくなる。
+
+実装方針
+もくもく会でよく使用されるタグを抽出し、トレンドや人気のあるトピックを表示する機能を追加する。
+ユーザープロフィールにおいて、タグを表示する機能を追加する。
+```

app/controllers/mypage/profiles_controller.rb

@@ -17,6 +17,6 @@ def update
   private
 
   def profile_params
-    params.require(:user).permit(:name, :avatar)
+    params.require(:user).permit(:name, :avatar, :hobby, :profile)
   end
 end

app/controllers/relationships_controller.rb

@@ -0,0 +1,12 @@
+class RelationshipsController < ApplicationController
+  def create
+    current_user.follow(params[:user_id])
+    redirect_to request.referer
+    end
+
+  # フォロー外すとき
+  def destroy
+    current_user.unfollow(params[:user_id])
+    redirect_to request.referer  
+    end
+end

app/controllers/users_controller.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 class UsersController < ApplicationController
+  before_action :set_user, only: [:show, :follows, :followers]
   def new
     @user = User.new
   end
@@ -16,6 +17,24 @@ def create
     end
   end
 
+  def show
+  end
+
+  def follows
+    @users = @user.following_users
+  end
+
+  # フォロワー一覧
+  def followers
+    @follower_users = @user.follower_users
+  end
+
+  private
+
+  def set_user
+    @user = User.find(params[:id])
+  end
+
   def user_params
     params.require(:user).permit(:email, :name, :password, :password_confirmation)
   end

app/models/relationship.rb

@@ -0,0 +1,4 @@
+class Relationship < ApplicationRecord
+  belongs_to :follower, class_name: "User"
+  belongs_to :followed, class_name: "User"
+end

app/models/user.rb

@@ -14,6 +14,13 @@ class User < ApplicationRecord
   has_many :notification_timings, through: :user_notification_timings
   has_one_attached :avatar
 
+  has_many :followers, class_name: "Relationship", foreign_key: "follower_id", dependent: :destroy
+  has_many :followeds, class_name: "Relationship", foreign_key: "followed_id", dependent: :destroy
+
+  # 一覧画面で使う
+  has_many :following_users, through: :followers, source: :followed
+  has_many :follower_users, through: :followeds, source: :follower
+
   validates :password, length: { minimum: 3 }, if: -> { new_record? || changes[:crypted_password] }
   validates :password, confirmation: true, if: -> { new_record? || changes[:crypted_password] }
   validates :password_confirmation, presence: true, if: -> { new_record? || changes[:crypted_password] }
@@ -76,4 +83,18 @@ def allow_attended_to_event_notification?
   def allow_liked_event_notification?
     notification_timings.liked_event.present?
   end
+
+  def follow(user_id)
+    followers.create(followed_id: user_id)
+  end
+
+  #　フォローを外すときの処理
+  def unfollow(user_id)
+    followers.find_by(followed_id: user_id)&.destroy
+  end
+
+  #フォローしていればtrueを返す
+  def following?(user)
+    following_users.include?(user)
+  end	 
 end

app/views/events/_event.html.erb

@@ -23,7 +23,7 @@
       <div class="d-flex align-items-center justify-content-between">
         <div class="d-flex align-items-center gap-3">
           <%= image_tag event.user.decorate.avatar, class: 'avatar-sm rounded-circle' %>
-          <%= event.user.name %>
+          <%= link_to event.user.name, user_path(event.user) %>
         </div>
         <% if logged_in? %>
           <div id="js-event-bookmark-<%= event.id %>">

app/views/events/show.html.erb

@@ -57,7 +57,7 @@
         <div class="card-body">
           <div class="d-flex align-items-center gap-3 mb-3">
             <%= image_tag @event.user.decorate.avatar, class: 'rounded-circle avatar-lg' %>
-            <%= @event.user.name %>
+            <%= link_to @event.user.name, user_path(@event.user) %>
           </div>
           <div class="p-3 bg-light">
             イベント数
@@ -112,7 +112,11 @@
         </div>
         <div class="card-body">
            <ul class="list-unstyled">
-             <%= render partial: 'events/attendee', collection: @event.attendees %>
+            <% @event.attendees.each do |attendee| %>
+              <li>
+                <%= link_to attendee.name, user_path(attendee) %>
+              </li>
+            <% end %>
            </ul>
         </div>
       </div>

app/views/mypage/profiles/show.html.erb

@@ -38,6 +38,14 @@
           <%= f.label :name, class: 'form-label' %>
           <%= f.text_field :name, class: 'form-control', placeholder: 'らんてくん' %>
         </div>
+        <div class="mb-3">
+          <%= f.label :hobby, class: 'form-label' %>
+          <%= f.text_field :hobby, class: 'form-control', placeholder: '趣味' %>
+        </div>
+        <div class="mb-3">
+          <%= f.label :profile, class: 'form-label' %>
+          <%= f.text_area :profile, class: 'form-control', placeholder: 'プロフィール情報' %>
+        </div>
         <div class="col-12">
           <!-- Button -->
           <%= f.submit class: 'btn btn-primary' %>

app/views/users/show.html.erb

@@ -0,0 +1,10 @@
+<h1><%= @user.name %> のプロフィール</h1>
+
+<p><strong>Hobby:</strong> <%= @user.hobby %></p>
+<p><strong>Profile:</strong> <%= @user.profile %></p>
+
+<% if current_user.following?(@user) %>
+  <%= link_to "フォローを外す", user_relationships_path(@user.id), method: :delete %>
+<% else %>
+  <%= link_to "フォローする", user_relationships_path(@user.id), method: :post %>
+<% end %>

config/routes.rb

@@ -9,7 +9,13 @@
   delete 'logout', to: 'sessions#destroy'
   get 'signup', to: 'users#new'
   post 'signup', to: 'users#create'
-  resources :users, only: %i[new create]
+  resources :users, only: %i[new create show] do
+    member do
+      get :follows, :followers
+    end
+      resource :relationships, only: [:create, :destroy]
+  end
+
   resources :events do
     collection do
       get :future

db/migrate/20231022153030_add_profile_and_hobby_to_users.rb

@@ -0,0 +1,6 @@
+class AddProfileAndHobbyToUsers < ActiveRecord::Migration[6.1]
+  def change
+    add_column :users, :profile, :string
+    add_column :users, :hobby, :string
+  end
+end

db/migrate/20231022154826_create_relationships.rb

@@ -0,0 +1,10 @@
+class CreateRelationships < ActiveRecord::Migration[6.1]
+  def change
+    create_table :relationships do |t|
+      t.integer :follower_id
+      t.integer :followed_id
+
+      t.timestamps
+    end
+  end
+end

spec/decorators/relationship_decorator_spec.rb

@@ -0,0 +1,4 @@
+require 'rails_helper'
+
+RSpec.describe RelationshipDecorator do
+end

spec/factories/relationships.rb

@@ -0,0 +1,6 @@
+FactoryBot.define do
+  factory :relationship do
+    association :follower, factory: :user
+    association :followed, factory: :user
+  end
+end

spec/models/relationship_spec.rb

@@ -0,0 +1,5 @@
+require 'rails_helper'
+
+RSpec.describe Relationship, type: :model do
+  pending "add some examples to (or delete) #{__FILE__}"
+end

spec/requests/relationships_spec.rb

@@ -0,0 +1,7 @@
+require 'rails_helper'
+
+RSpec.describe "Relationships", type: :request do
+  describe "GET /index" do
+    pending "add some examples (or delete) #{__FILE__}"
+  end
+end