feat: add user index page and update navigation

- Implement users index action in UsersController
- Create view for displaying all users with gravatar
- Update header to link to users index
- Add styles for user list display

This commit introduces a new feature that allows logged-in users to
view a list of all registered users. It includes necessary
controller actions, view templates, and styling to improve the
user interface.

app/assets/stylesheets/custom.scss

@@ -2,6 +2,7 @@
 
 /* color */
 $light-gray: #777;
+$gray-lighter: #D3D3D3;
 
 /* universal */
 body {
@@ -187,3 +188,14 @@ input {
   width: auto;
   margin-left: 0;
 }
+
+/* Users index */
+.users {
+  list-style: none;
+  margin: 0;
+  li {
+    overflow: auto;
+    padding: 10px 0;
+    border-bottom: 1px solid $gray-lighter;
+  }
+}

app/controllers/users_controller.rb

@@ -1,7 +1,12 @@
 class UsersController < ApplicationController
   include SessionsHelper
-  before_action :logged_in_user,  only: [ :edit, :update ]
+  before_action :logged_in_user,  only: [ :index, :edit, :update ]
   before_action :correct_user,    only: [ :edit, :update ]
+
+  def index
+    @users = User.all
+  end
+
   def show
     @user = User.find(params[:id])
     # debugger

app/helpers/users_helper.rb

@@ -1,5 +1,6 @@
 module UsersHelper
-  def gravatar_for(user, size: 80)
+  def gravatar_for(user, options = { size: 80 })
+    size = options[:size]
     gravatar_id = Digest::MD5.hexdigest(user.email.downcase)
     gravatar_url = "https://secure.gravatar.com/avatar/#{gravatar_id}?s=#{size}"
     image_tag(gravatar_url, alt: user.name, class: "gravatar")

app/views/layouts/_header.html.erb

@@ -18,7 +18,7 @@
         <li><%= link_to "Home", root_url %></li>
         <li><%= link_to "Help", help_url %></li>
         <% if logged_in? %>
-          <li><%= link_to "Users", '#' %></li>
+          <li><%= link_to "Users", users_path %></li>
           <li class="dropdown">
             <a href="#" class="dropdown-toggle" data-toggle="dropdown">
               Account <b class="caret"></b>

app/views/users/index.html.erb

@@ -0,0 +1,12 @@
+<% provide(:title, 'All users') %>
+
+<h1>All users</h1>
+
+<ul class="users">
+  <% @users.each do |user| %>
+    <li>
+      <%= gravatar_for user, size: 50 %>
+      <%= link_to user.name, user %>
+    </li>
+  <% end %>
+</ul>

test/controllers/users_controller_test.rb

@@ -10,6 +10,11 @@ class UsersControllerTest < ActionDispatch::IntegrationTest
     assert_response :success
   end
 
+  test "should redirect index when not logged in" do
+    get users_path
+    assert_redirected_to login_url
+  end
+
   test "Should get sign up title" do
     get signup_path
     assert_response :success