DEV: Ability to collect stats without exposing them via API (#23933)

This adds the ability to collect stats without exposing them 
among other stats via API.

The most important thing I wanted to achieve is to provide 
an API where stats are not exposed by default, and a developer 
has to explicitly specify that they should be 
exposed (`expose_via_api: true`). Implementing an opposite 
solution would be simpler, but that's less safe in terms of 
potential security issues. 

When working on this, I had to refactor the current solution. 
I would go even further with the refactoring, but the next steps 
seem to be going too far in changing the solution we have, 
and that would also take more time. Two things that can be 
improved in the future:
1. Data structures for holding stats can be further improved
2. Core stats are hard-coded in the About template (it's hard 
to fix it without correcting data structures first, see point 1):
    63a0700d45/app/views/about/index.html.erb (L61-L101)

The most significant refactorings are:
1. Introducing the `Stat` model
2. Aligning the way the core and the plugin stats' are registered

app/assets/javascripts/discourse/app/templates/about.hbs

@@ -110,21 +110,21 @@
                 <td>{{number this.model.stats.topics_last_day}}</td>
                 <td>{{number this.model.stats.topics_7_days}}</td>
                 <td>{{number this.model.stats.topics_30_days}}</td>
-                <td>{{number this.model.stats.topic_count}}</td>
+                <td>{{number this.model.stats.topics_count}}</td>
               </tr>
               <tr class="about-post-count">
                 <td>{{i18n "about.post_count"}}</td>
                 <td>{{number this.model.stats.posts_last_day}}</td>
                 <td>{{number this.model.stats.posts_7_days}}</td>
                 <td>{{number this.model.stats.posts_30_days}}</td>
-                <td>{{number this.model.stats.post_count}}</td>
+                <td>{{number this.model.stats.posts_count}}</td>
               </tr>
               <tr class="about-user-count">
                 <td>{{i18n "about.user_count"}}</td>
                 <td>{{number this.model.stats.users_last_day}}</td>
                 <td>{{number this.model.stats.users_7_days}}</td>
                 <td>{{number this.model.stats.users_30_days}}</td>
-                <td>{{number this.model.stats.user_count}}</td>
+                <td>{{number this.model.stats.users_count}}</td>
               </tr>
               <tr class="about-active-user-count">
                 <td>{{i18n "about.active_user_count"}}</td>
@@ -138,7 +138,7 @@
                 <td>{{number this.model.stats.likes_last_day}}</td>
                 <td>{{number this.model.stats.likes_7_days}}</td>
                 <td>{{number this.model.stats.likes_30_days}}</td>
-                <td>{{number this.model.stats.like_count}}</td>
+                <td>{{number this.model.stats.likes_count}}</td>
               </tr>
               {{#each
                 this.site.displayed_about_plugin_stat_groups

app/models/about.rb

@@ -2,10 +2,7 @@
 
 class About
   def self.displayed_plugin_stat_groups
-    DiscoursePluginRegistry
-      .about_stat_groups
-      .select { |stat_group| stat_group[:show_in_ui] }
-      .map { |stat_group| stat_group[:name] }
+    DiscoursePluginRegistry.stats.select { |stat| stat.show_in_ui }.map { |stat| stat.name }
   end
 
   class CategoryMods
@@ -28,7 +25,7 @@ class About
   end
 
   def self.fetch_stats
-    About.new.stats
+    Stat.api_stats
   end
 
   def initialize(user = nil)
@@ -64,57 +61,7 @@ class About
   end
 
   def stats
-    @stats ||= {
-      topic_count: Topic.listable_topics.count,
-      topics_last_day: Topic.listable_topics.where("created_at > ?", 1.days.ago).count,
-      topics_7_days: Topic.listable_topics.where("created_at > ?", 7.days.ago).count,
-      topics_30_days: Topic.listable_topics.where("created_at > ?", 30.days.ago).count,
-      post_count: Post.count,
-      posts_last_day: Post.where("created_at > ?", 1.days.ago).count,
-      posts_7_days: Post.where("created_at > ?", 7.days.ago).count,
-      posts_30_days: Post.where("created_at > ?", 30.days.ago).count,
-      user_count: User.real.count,
-      users_last_day: User.real.where("created_at > ?", 1.days.ago).count,
-      users_7_days: User.real.where("created_at > ?", 7.days.ago).count,
-      users_30_days: User.real.where("created_at > ?", 30.days.ago).count,
-      active_users_last_day: User.where("last_seen_at > ?", 1.days.ago).count,
-      active_users_7_days: User.where("last_seen_at > ?", 7.days.ago).count,
-      active_users_30_days: User.where("last_seen_at > ?", 30.days.ago).count,
-      like_count: UserAction.where(action_type: UserAction::LIKE).count,
-      likes_last_day:
-        UserAction.where(action_type: UserAction::LIKE).where("created_at > ?", 1.days.ago).count,
-      likes_7_days:
-        UserAction.where(action_type: UserAction::LIKE).where("created_at > ?", 7.days.ago).count,
-      likes_30_days:
-        UserAction.where(action_type: UserAction::LIKE).where("created_at > ?", 30.days.ago).count,
-    }.merge(plugin_stats)
-  end
-
-  def plugin_stats
-    final_plugin_stats = {}
-    DiscoursePluginRegistry.about_stat_groups.each do |stat_group|
-      begin
-        stats = stat_group[:block].call
-      rescue StandardError => err
-        Discourse.warn_exception(
-          err,
-          message: "Unexpected error when collecting #{stat_group[:name]} About stats.",
-        )
-        next
-      end
-
-      if !stats.key?(:last_day) || !stats.key?("7_days") || !stats.key?("30_days") ||
-           !stats.key?(:count)
-        Rails.logger.warn(
-          "Plugin stat group #{stat_group[:name]} for About stats does not have all required keys, skipping.",
-        )
-      else
-        final_plugin_stats.merge!(
-          stats.transform_keys { |key| "#{stat_group[:name]}_#{key}".to_sym },
-        )
-      end
-    end
-    final_plugin_stats
+    @stats ||= About.fetch_stats
   end
 
   def category_moderators

app/models/stat.rb

@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+class Stat
+  def initialize(name, show_in_ui: false, expose_via_api: false, &block)
+    @name = name
+    @show_in_ui = show_in_ui
+    @expose_via_api = expose_via_api
+    @block = block
+  end
+
+  attr_reader :name, :expose_via_api, :show_in_ui
+
+  def calculate
+    @block.call.transform_keys { |key| build_key(key) }
+  rescue StandardError => err
+    Discourse.warn_exception(err, message: "Unexpected error when collecting #{@name} About stats.")
+    {}
+  end
+
+  def self.all_stats
+    calculate(_all_stats)
+  end
+
+  def self.api_stats
+    calculate(_api_stats)
+  end
+
+  private
+
+  def build_key(key)
+    "#{@name}_#{key}".to_sym
+  end
+
+  def self._all_stats
+    core_stats.concat(plugin_stats)
+  end
+
+  def self.calculate(stats)
+    stats.map { |stat| stat.calculate }.reduce(Hash.new, :merge)
+  end
+
+  def self.core_stats
+    [
+      Stat.new("topics", show_in_ui: true, expose_via_api: true) { Statistics.topics },
+      Stat.new("posts", show_in_ui: true, expose_via_api: true) { Statistics.posts },
+      Stat.new("users", show_in_ui: true, expose_via_api: true) { Statistics.users },
+      Stat.new("active_users", show_in_ui: true, expose_via_api: true) { Statistics.active_users },
+      Stat.new("likes", show_in_ui: true, expose_via_api: true) { Statistics.likes },
+    ]
+  end
+
+  def self._api_stats
+    _all_stats.select { |stat| stat.expose_via_api }
+  end
+
+  def self.plugin_stats
+    DiscoursePluginRegistry.stats
+  end
+
+  private_class_method :_all_stats, :calculate, :core_stats, :_api_stats, :plugin_stats
+end

app/serializers/about_serializer.rb

@@ -30,7 +30,7 @@ class AboutSerializer < ApplicationSerializer
   end
 
   def stats
-    object.class.fetch_cached_stats || Jobs::AboutStats.new.execute({})
+    object.class.fetch_cached_stats
   end
 
   def include_contact_url?

lib/discourse_plugin_registry.rb

@@ -113,7 +113,7 @@ class DiscoursePluginRegistry
 
   define_filtered_register :search_groups_set_query_callbacks
 
-  define_filtered_register :about_stat_groups
+  define_filtered_register :stats
   define_filtered_register :bookmarkables
 
   define_filtered_register :list_suggested_for_providers

lib/plugin/instance.rb

@@ -1110,7 +1110,7 @@ class Plugin::Instance
   # but all stats will be shown on the /about.json route. For example take
   # this usage:
   #
-  # register_about_stat_group("chat_messages") do
+  # register_stat("chat_messages") do
   #   { last_day: 1, "7_days" => 10, "30_days" => 100, count: 1000, previous_30_days: 150 }
   # end
   #
@@ -1132,18 +1132,12 @@ class Plugin::Instance
   # group of stats is shown on the site About page in the Site Statistics
   # table. Some stats may be needed purely for reporting purposes and thus
   # do not need to be shown in the UI to admins/users.
-  def register_about_stat_group(plugin_stat_group_name, show_in_ui: false, &block)
+  def register_stat(name, show_in_ui: false, expose_via_api: false, &block)
     # We do not want to register and display the same group multiple times.
-    if DiscoursePluginRegistry.about_stat_groups.any? { |stat_group|
-         stat_group[:name] == plugin_stat_group_name
-       }
-      return
-    end
+    return if DiscoursePluginRegistry.stats.any? { |stat| stat.name == name }
 
-    DiscoursePluginRegistry.register_about_stat_group(
-      { name: plugin_stat_group_name, show_in_ui: show_in_ui, block: block },
-      self,
-    )
+    stat = Stat.new(name, show_in_ui: show_in_ui, expose_via_api: expose_via_api, &block)
+    DiscoursePluginRegistry.register_stat(stat, self)
   end
 
   ##

lib/statistics.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+class Statistics
+  def self.active_users
+    {
+      last_day: User.where("last_seen_at > ?", 1.days.ago).count,
+      "7_days": User.where("last_seen_at > ?", 7.days.ago).count,
+      "30_days": User.where("last_seen_at > ?", 30.days.ago).count,
+    }
+  end
+
+  def self.likes
+    {
+      last_day:
+        UserAction.where(action_type: UserAction::LIKE).where("created_at > ?", 1.days.ago).count,
+      "7_days":
+        UserAction.where(action_type: UserAction::LIKE).where("created_at > ?", 7.days.ago).count,
+      "30_days":
+        UserAction.where(action_type: UserAction::LIKE).where("created_at > ?", 30.days.ago).count,
+      count: UserAction.where(action_type: UserAction::LIKE).count,
+    }
+  end
+
+  def self.posts
+    {
+      last_day: Post.where("created_at > ?", 1.days.ago).count,
+      "7_days": Post.where("created_at > ?", 7.days.ago).count,
+      "30_days": Post.where("created_at > ?", 30.days.ago).count,
+      count: Post.count,
+    }
+  end
+
+  def self.topics
+    {
+      last_day: Topic.listable_topics.where("created_at > ?", 1.days.ago).count,
+      "7_days": Topic.listable_topics.where("created_at > ?", 7.days.ago).count,
+      "30_days": Topic.listable_topics.where("created_at > ?", 30.days.ago).count,
+      count: Topic.listable_topics.count,
+    }
+  end
+
+  def self.users
+    {
+      last_day: User.real.where("created_at > ?", 1.days.ago).count,
+      "7_days": User.real.where("created_at > ?", 7.days.ago).count,
+      "30_days": User.real.where("created_at > ?", 30.days.ago).count,
+      count: User.real.count,
+    }
+  end
+end

plugins/chat/lib/chat/statistics.rb

@@ -4,40 +4,40 @@ module Chat
   class Statistics
     def self.about_messages
       {
-        :last_day => Chat::Message.where("created_at > ?", 1.days.ago).count,
-        "7_days" => Chat::Message.where("created_at > ?", 7.days.ago).count,
-        "30_days" => Chat::Message.where("created_at > ?", 30.days.ago).count,
-        :previous_30_days =>
+        last_day: Chat::Message.where("created_at > ?", 1.days.ago).count,
+        "7_days": Chat::Message.where("created_at > ?", 7.days.ago).count,
+        "30_days": Chat::Message.where("created_at > ?", 30.days.ago).count,
+        previous_30_days:
           Chat::Message.where("created_at BETWEEN ? AND ?", 60.days.ago, 30.days.ago).count,
-        :count => Chat::Message.count,
+        count: Chat::Message.count,
       }
     end
 
     def self.about_channels
       {
-        :last_day => Chat::Channel.where(status: :open).where("created_at > ?", 1.days.ago).count,
-        "7_days" => Chat::Channel.where(status: :open).where("created_at > ?", 7.days.ago).count,
-        "30_days" => Chat::Channel.where(status: :open).where("created_at > ?", 30.days.ago).count,
-        :previous_30_days =>
+        last_day: Chat::Channel.where(status: :open).where("created_at > ?", 1.days.ago).count,
+        "7_days": Chat::Channel.where(status: :open).where("created_at > ?", 7.days.ago).count,
+        "30_days": Chat::Channel.where(status: :open).where("created_at > ?", 30.days.ago).count,
+        previous_30_days:
           Chat::Channel
             .where(status: :open)
             .where("created_at BETWEEN ? AND ?", 60.days.ago, 30.days.ago)
             .count,
-        :count => Chat::Channel.where(status: :open).count,
+        count: Chat::Channel.where(status: :open).count,
       }
     end
 
     def self.about_users
       {
-        :last_day => Chat::Message.where("created_at > ?", 1.days.ago).distinct.count(:user_id),
-        "7_days" => Chat::Message.where("created_at > ?", 7.days.ago).distinct.count(:user_id),
-        "30_days" => Chat::Message.where("created_at > ?", 30.days.ago).distinct.count(:user_id),
-        :previous_30_days =>
+        last_day: Chat::Message.where("created_at > ?", 1.days.ago).distinct.count(:user_id),
+        "7_days": Chat::Message.where("created_at > ?", 7.days.ago).distinct.count(:user_id),
+        "30_days": Chat::Message.where("created_at > ?", 30.days.ago).distinct.count(:user_id),
+        previous_30_days:
           Chat::Message
             .where("created_at BETWEEN ? AND ?", 60.days.ago, 30.days.ago)
             .distinct
             .count(:user_id),
-        :count => Chat::Message.distinct.count(:user_id),
+        count: Chat::Message.distinct.count(:user_id),
       }
     end
 

plugins/chat/plugin.rb

@@ -480,11 +480,13 @@ after_initialize do
 
   register_email_unsubscriber("chat_summary", EmailControllerHelper::ChatSummaryUnsubscriber)
 
-  register_about_stat_group("chat_messages", show_in_ui: true) { Chat::Statistics.about_messages }
+  register_stat("chat_messages", show_in_ui: true, expose_via_api: true) do
+    Chat::Statistics.about_messages
+  end
 
-  register_about_stat_group("chat_channels") { Chat::Statistics.about_channels }
+  register_stat("chat_channels", expose_via_api: true) { Chat::Statistics.about_channels }
 
-  register_about_stat_group("chat_users") { Chat::Statistics.about_users }
+  register_stat("chat_users", expose_via_api: true) { Chat::Statistics.about_users }
 
   # Make sure to update spec/system/hashtag_autocomplete_spec.rb when changing this.
   register_hashtag_data_source(Chat::ChannelHashtagDataSource)

plugins/chat/spec/lib/chat/statistics_spec.rb

@@ -79,8 +79,8 @@ describe Chat::Statistics do
     it "counts non-deleted messages created in all status channels in the time period accurately" do
       about_messages = described_class.about_messages
       expect(about_messages[:last_day]).to eq(1)
-      expect(about_messages["7_days"]).to eq(3)
-      expect(about_messages["30_days"]).to eq(7)
+      expect(about_messages[:"7_days"]).to eq(3)
+      expect(about_messages[:"30_days"]).to eq(7)
       expect(about_messages[:previous_30_days]).to eq(2)
       expect(about_messages[:count]).to eq(10)
     end
@@ -90,8 +90,8 @@ describe Chat::Statistics do
     it "counts open channels created in the time period accurately" do
       about_channels = described_class.about_channels
       expect(about_channels[:last_day]).to eq(1)
-      expect(about_channels["7_days"]).to eq(3)
-      expect(about_channels["30_days"]).to eq(5)
+      expect(about_channels[:"7_days"]).to eq(3)
+      expect(about_channels[:"30_days"]).to eq(5)
       expect(about_channels[:previous_30_days]).to eq(1)
       expect(about_channels[:count]).to eq(6)
     end
@@ -101,8 +101,8 @@ describe Chat::Statistics do
     it "counts any users who have sent any message to a chat channel in the time periods accurately" do
       about_users = described_class.about_users
       expect(about_users[:last_day]).to eq(1)
-      expect(about_users["7_days"]).to eq(2)
-      expect(about_users["30_days"]).to eq(3)
+      expect(about_users[:"7_days"]).to eq(2)
+      expect(about_users[:"30_days"]).to eq(3)
       expect(about_users[:previous_30_days]).to eq(2)
       expect(about_users[:count]).to eq(4)
     end

spec/lib/discourse_hub_spec.rb

@@ -23,9 +23,9 @@ RSpec.describe DiscourseHub do
         DiscourseHub.stats_fetched_at = 8.days.ago
         json = JSON.parse(DiscourseHub.version_check_payload.to_json)
 
-        expect(json["topic_count"]).to be_present
-        expect(json["post_count"]).to be_present
-        expect(json["user_count"]).to be_present
+        expect(json["topics_count"]).to be_present
+        expect(json["posts_count"]).to be_present
+        expect(json["users_count"]).to be_present
         expect(json["topics_7_days"]).to be_present
         expect(json["topics_30_days"]).to be_present
         expect(json["posts_7_days"]).to be_present
@@ -34,7 +34,7 @@ RSpec.describe DiscourseHub do
         expect(json["users_30_days"]).to be_present
         expect(json["active_users_7_days"]).to be_present
         expect(json["active_users_30_days"]).to be_present
-        expect(json["like_count"]).to be_present
+        expect(json["likes_count"]).to be_present
         expect(json["likes_7_days"]).to be_present
         expect(json["likes_30_days"]).to be_present
         expect(json["installed_version"]).to be_present

spec/lib/plugin/instance_spec.rb

@@ -808,15 +808,15 @@ RSpec.describe Plugin::Instance do
     end
   end
 
-  describe "#register_about_stat_group" do
+  describe "#register_stat" do
     let(:plugin) { Plugin::Instance.new }
 
     after { DiscoursePluginRegistry.reset! }
 
     it "registers an about stat group correctly" do
       stats = { :last_day => 1, "7_days" => 10, "30_days" => 100, :count => 1000 }
-      plugin.register_about_stat_group("some_group", show_in_ui: true) { stats }
-      expect(About.new.plugin_stats.with_indifferent_access).to match(
+      plugin.register_stat("some_group", show_in_ui: true) { stats }
+      expect(Stat.all_stats.with_indifferent_access).to match(
         hash_including(
           some_group_last_day: 1,
           some_group_7_days: 10,
@@ -828,15 +828,15 @@ RSpec.describe Plugin::Instance do
 
     it "hides the stat group from the UI by default" do
       stats = { :last_day => 1, "7_days" => 10, "30_days" => 100, :count => 1000 }
-      plugin.register_about_stat_group("some_group") { stats }
+      plugin.register_stat("some_group") { stats }
       expect(About.displayed_plugin_stat_groups).to eq([])
     end
 
     it "does not allow duplicate named stat groups" do
       stats = { :last_day => 1, "7_days" => 10, "30_days" => 100, :count => 1000 }
-      plugin.register_about_stat_group("some_group") { stats }
-      plugin.register_about_stat_group("some_group") { stats }
-      expect(DiscoursePluginRegistry.about_stat_groups.count).to eq(1)
+      plugin.register_stat("some_group") { stats }
+      plugin.register_stat("some_group") { stats }
+      expect(DiscoursePluginRegistry.stats.count).to eq(1)
     end
   end
 

spec/models/about_spec.rb

@@ -5,9 +5,9 @@ RSpec.describe About do
     include_examples "stats cacheable"
   end
 
-  def register_about_stat_group(name, stats_block, show_in_ui: true)
-    DiscoursePluginRegistry.register_about_stat_group(
-      { name: name, show_in_ui: show_in_ui, block: stats_block },
+  def register_stat(name, stats_block)
+    DiscoursePluginRegistry.register_stat(
+      Stat.new(name, show_in_ui: true, expose_via_api: true, &stats_block),
       stub(enabled?: true),
     )
   end
@@ -17,7 +17,7 @@ RSpec.describe About do
   describe "#stats" do
     it "adds plugin stats to the output" do
       stats = { :last_day => 1, "7_days" => 10, "30_days" => 100, :count => 1000 }
-      register_about_stat_group("some_group", Proc.new { stats })
+      register_stat("some_group", Proc.new { stats })
       expect(described_class.new.stats.with_indifferent_access).to match(
         hash_including(
           some_group_last_day: 1,
@@ -30,7 +30,7 @@ RSpec.describe About do
 
     it "does not add plugin stats to the output if they are missing one of the required keys" do
       stats = { "7_days" => 10, "30_days" => 100, :count => 1000 }
-      register_about_stat_group("some_group", Proc.new { stats })
+      register_stat("some_group", Proc.new { stats })
       expect(described_class.new.stats).not_to match(
         hash_including(
           some_group_last_day: 1,
@@ -43,8 +43,8 @@ RSpec.describe About do
 
     it "does not error if any of the plugin stat blocks throw an error and still adds the non-errored stats to output" do
       stats = { :last_day => 1, "7_days" => 10, "30_days" => 100, :count => 1000 }
-      register_about_stat_group("some_group", Proc.new { stats })
-      register_about_stat_group("other_group", Proc.new { raise StandardError })
+      register_stat("some_group", Proc.new { stats })
+      register_stat("other_group", Proc.new { raise StandardError })
       expect(described_class.new.stats.with_indifferent_access).to match(
         hash_including(
           some_group_last_day: 1,

spec/requests/site_controller_spec.rb

@@ -40,9 +40,9 @@ RSpec.describe SiteController do
       json = response.parsed_body
 
       expect(response.status).to eq(200)
-      expect(json["topic_count"]).to be_present
-      expect(json["post_count"]).to be_present
-      expect(json["user_count"]).to be_present
+      expect(json["topics_count"]).to be_present
+      expect(json["posts_count"]).to be_present
+      expect(json["users_count"]).to be_present
       expect(json["topics_7_days"]).to be_present
       expect(json["topics_30_days"]).to be_present
       expect(json["posts_7_days"]).to be_present
@@ -51,7 +51,7 @@ RSpec.describe SiteController do
       expect(json["users_30_days"]).to be_present
       expect(json["active_users_7_days"]).to be_present
       expect(json["active_users_30_days"]).to be_present
-      expect(json["like_count"]).to be_present
+      expect(json["likes_count"]).to be_present
       expect(json["likes_7_days"]).to be_present
       expect(json["likes_30_days"]).to be_present
     end
@@ -62,5 +62,32 @@ RSpec.describe SiteController do
       get "/site/statistics.json"
       expect(response).to redirect_to "/"
     end
+
+    it "returns exposable stats only" do
+      Discourse.redis.del(About.stats_cache_key)
+
+      SiteSetting.login_required = true
+      SiteSetting.share_anonymized_statistics = true
+
+      plugin = Plugin::Instance.new
+      plugin.register_stat("private_stat", expose_via_api: false) do
+        { :last_day => 1, "7_days" => 2, "30_days" => 3, :count => 4 }
+      end
+      plugin.register_stat("exposable_stat", expose_via_api: true) do
+        { :last_day => 11, "7_days" => 12, "30_days" => 13, :count => 14 }
+      end
+
+      get "/site/statistics.json"
+      json = response.parsed_body
+
+      expect(json["exposable_stat_last_day"]).to be(11)
+      expect(json["exposable_stat_7_days"]).to be(12)
+      expect(json["exposable_stat_30_days"]).to be(13)
+      expect(json["exposable_stat_count"]).to be(14)
+      expect(json["private_stat_last_day"]).not_to be_present
+      expect(json["private_stat_7_days"]).not_to be_present
+      expect(json["private_stat_30_days"]).not_to be_present
+      expect(json["private_stat_count"]).not_to be_present
+    end
   end
 end

spec/serializers/about_serializer_spec.rb

@@ -42,4 +42,32 @@ RSpec.describe AboutSerializer do
       expect(json[:contact_email]).to eq(SiteSetting.contact_email)
     end
   end
+
+  describe "#stats" do
+    let(:plugin) { Plugin::Instance.new }
+
+    it "serialize exposable stats only" do
+      Discourse.redis.del(About.stats_cache_key)
+
+      plugin.register_stat("private_stat", expose_via_api: false) do
+        { :last_day => 1, "7_days" => 2, "30_days" => 3, :count => 4 }
+      end
+      plugin.register_stat("exposable_stat", expose_via_api: true) do
+        { :last_day => 11, "7_days" => 12, "30_days" => 13, :count => 14 }
+      end
+
+      serializer = AboutSerializer.new(About.new(user), scope: Guardian.new(user), root: nil)
+      json = serializer.as_json
+
+      stats = json[:stats]
+      expect(stats["exposable_stat_last_day"]).to be(11)
+      expect(stats["exposable_stat_7_days"]).to be(12)
+      expect(stats["exposable_stat_30_days"]).to be(13)
+      expect(stats["exposable_stat_count"]).to be(14)
+      expect(stats["private_stat_last_day"]).not_to be_present
+      expect(stats["private_stat_7_days"]).not_to be_present
+      expect(stats["private_stat_30_days"]).not_to be_present
+      expect(stats["private_stat_count"]).not_to be_present
+    end
+  end
 end