Conditionally reducing dashboard chatter for users (#16999)

This commit provides two things:

1.  Some notes related to my analysis regarding the dashboard
2.  Conditional redirects and rendering based on article policies

The code comments say most of what I want to say, but to reiterate:

When a user can't create articles nor do they already have published
articles, then we don't want to avoid showing them stats related to
articles.

Closes forem/forem#16913
Related to forem/forem#16908 and forem/forem#16931

app/controllers/dashboards_controller.rb

@@ -1,3 +1,16 @@
+# @note The actions of this class are overloaded with three concerns:
+#
+#       - the current user
+#       - a given user
+#       - a given organization
+#
+#       The implementation details are such that things silently "fallback" to the current user's
+#       information.  This fallback happens when we have quasi-policy checks say the current user
+#       can't access the given user or given organization.
+#
+#       [@jeremyf] I'm including these notes for future refactors, as I've spent time trying to
+#       improve legibility of the code but there are logical assumptions that require revisiting
+#       (hence https://github.com/forem/forem/issues/16931).
 class DashboardsController < ApplicationController
   before_action :set_no_cache_header
   before_action :authenticate_user!
@@ -7,15 +20,22 @@ class DashboardsController < ApplicationController
   def show
     fetch_and_authorize_user
     target = @user
+    # NOTE: This is a subtle policy check happening here that we are not encapsulating
     not_authorized if params[:org_id] && !@user.org_admin?(params[:org_id] || @user.any_admin?)
 
     @organizations = @user.admin_organizations
 
+    # NOTE: This logic is a super set of the above not_authorized check
     if params[:which] == "organization" && params[:org_id] && (@user.org_admin?(params[:org_id]) || @user.any_admin?)
       target = @organizations.find_by(id: params[:org_id])
       @organization = target
       @articles = target.articles
     else
+      # This redirect assumes that the dashboards#show action renders article specific information.
+      # When a user doesn't have articles nor can they create them, we want to send them somewhere
+      # else.
+      redirect_to dashboard_following_tags_path unless policy(Article).has_existing_articles_or_can_create_new_ones?
+
       # if the target is a user, we need to eager load the organization
       @articles = target.articles.includes(:organization)
     end
@@ -92,6 +112,7 @@ class DashboardsController < ApplicationController
             else
               current_user
             end
+    # NOTE: later we expect @user so the `||` is a bit misleading.
     authorize (@user || User), :dashboard_show?
   end
 

app/views/dashboards/_actions.html.erb

@@ -1,5 +1,6 @@
 <nav class="hidden m:block" aria-label="Dashboards">
   <ul class="list-none p-0">
+    <% if policy(Article).has_existing_articles_or_can_create_new_ones? %>
     <li>
       <a class="crayons-link crayons-link--block <%= "crayons-link--current" if params[:action] == "show" && (params[:which] == "organization" || params[:which].blank?) %>"
         href="<%= dashboard_path %>"
@@ -26,6 +27,7 @@
         <span class="c-indicator"><%= @user.followers_count %></span>
       </a>
     </li>
+    <% end %>
 
     <li>
       <a class="crayons-link crayons-link--block <%= "crayons-link--current" if params[:action] == "following_tags" %>"
@@ -72,11 +74,13 @@
     </li>
     <%- end %>
 
+    <%- if policy(Article).has_existing_articles_or_can_create_new_ones? %>
     <li>
       <a class="crayons-link crayons-link--block" href="<%= dashboard_analytics_path %>">
         <%= t("views.dashboard.actions.analytics") %>
       </a>
     </li>
+    <%- end %>
 
   <% if @organizations && (params[:which].blank? || params[:which] == "organization") %>
     <% @organizations.each do |org| %>

spec/requests/dashboard_spec.rb

@@ -97,6 +97,25 @@ RSpec.describe "Dashboards", type: :request do
       end
     end
 
+    context "when logged but has no articles nor can create them" do
+      it "redirects to /dashboard/following_tags" do
+        sign_in user
+
+        # [@jeremyf] I'm choosing not to setup the exact conditions of the data for this to be true.
+        # Instead, I'm relying on that function to already be tested.
+        #
+        # rubocop:disable RSpec/AnyInstance
+        # Pundit does not make it easy to stub the policy().method questions so I'm using the any instance antics.
+        allow_any_instance_of(ArticlePolicy)
+          .to receive(:has_existing_articles_or_can_create_new_ones?)
+          .and_return(false)
+        # rubocop:enable RSpec/AnyInstance
+
+        get dashboard_path
+        expect(response).to redirect_to("/dashboard/following_tags")
+      end
+    end
+
     context "when logged in as a super admin" do
       it "renders the specified user's articles" do
         article