FEATURE: Support for publishing topics as pages (#9364)

If the feature is enabled, staff members can construct a URL and publish a
topic for others to browse without the regular Discourse chrome.

This is useful if you want to use Discourse like a CMS and publish
topics as articles, which can then be embedded into other systems.

spec/requests/published_pages_controller_spec.rb

@@ -0,0 +1,170 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe PublishedPagesController do
+  fab!(:published_page) { Fabricate(:published_page) }
+  fab!(:admin) { Fabricate(:admin) }
+  fab!(:user) { Fabricate(:user) }
+
+  context "when enabled" do
+    before do
+      SiteSetting.enable_page_publishing = true
+    end
+
+    context "check slug availability" do
+      it "returns true for a new slug" do
+        get "/pub/check-slug.json?slug=cool-slug-man"
+        expect(response).to be_successful
+        expect(response.parsed_body["valid_slug"]).to eq(true)
+      end
+
+      it "returns true for a new slug with whitespace" do
+        get "/pub/check-slug.json?slug=cool-slug-man%20"
+        expect(response).to be_successful
+        expect(response.parsed_body["valid_slug"]).to eq(true)
+      end
+
+      it "returns false for an empty value" do
+        get "/pub/check-slug.json?slug="
+        expect(response).to be_successful
+        expect(response.parsed_body["valid_slug"]).to eq(false)
+        expect(response.parsed_body["reason"]).to be_present
+      end
+
+      it "returns false for a reserved value" do
+        get "/pub/check-slug.json", params: { slug: "check-slug" }
+        expect(response).to be_successful
+        expect(response.parsed_body["valid_slug"]).to eq(false)
+        expect(response.parsed_body["reason"]).to be_present
+      end
+    end
+
+    context "show" do
+      it "returns 404 for a missing article" do
+        get "/pub/no-article-here-no-thx"
+        expect(response.status).to eq(404)
+      end
+
+      context "private topic" do
+        fab!(:group) { Fabricate(:group) }
+        fab!(:private_category) { Fabricate(:private_category, group: group) }
+
+        before do
+          published_page.topic.update!(category: private_category)
+        end
+
+        it "returns 403 for a topic you can't see" do
+          get published_page.path
+          expect(response.status).to eq(403)
+        end
+
+        context "as an admin" do
+          before do
+            sign_in(admin)
+          end
+
+          it "returns 200" do
+            get published_page.path
+            expect(response.status).to eq(200)
+          end
+        end
+      end
+
+      it "returns an error for an article you can't see" do
+        get "/pub/no-article-here-no-thx"
+        expect(response.status).to eq(404)
+      end
+
+      it "returns 200 for a valid article" do
+        get published_page.path
+        expect(response.status).to eq(200)
+      end
+    end
+
+    context "publishing" do
+      fab!(:topic) { Fabricate(:topic) }
+
+      it "returns invalid access for non-staff" do
+        sign_in(user)
+        put "/pub/by-topic/#{topic.id}.json", params: { published_page: { slug: 'cant-do-this' } }
+        expect(response.status).to eq(403)
+      end
+
+      context "with a valid staff account" do
+        before do
+          sign_in(admin)
+        end
+
+        it "creates the published page record" do
+          put "/pub/by-topic/#{topic.id}.json", params: { published_page: { slug: 'i-hate-salt' } }
+          expect(response).to be_successful
+          expect(response.parsed_body['published_page']).to be_present
+          expect(response.parsed_body['published_page']['slug']).to eq("i-hate-salt")
+
+          expect(PublishedPage.exists?(topic_id: response.parsed_body['published_page']['id'])).to eq(true)
+          expect(UserHistory.exists?(
+            acting_user_id: admin.id,
+            action: UserHistory.actions[:page_published],
+            topic_id: topic.id
+          )).to be(true)
+        end
+
+        it "returns an error if the slug is already taken" do
+          PublishedPage.create!(slug: 'i-hate-salt', topic: Fabricate(:topic))
+          put "/pub/by-topic/#{topic.id}.json", params: { published_page: { slug: 'i-hate-salt' } }
+          expect(response).not_to be_successful
+        end
+
+        it "returns an error if the topic already has been published" do
+          PublishedPage.create!(slug: 'already-done-pal', topic: topic)
+          put "/pub/by-topic/#{topic.id}.json", params: { published_page: { slug: 'i-hate-salt' } }
+          expect(response).to be_successful
+          expect(PublishedPage.exists?(topic_id: topic.id)).to eq(true)
+        end
+
+      end
+    end
+
+    context "destroy" do
+
+      it "returns invalid access for non-staff" do
+        sign_in(user)
+        delete "/pub/by-topic/#{published_page.topic_id}.json"
+        expect(response.status).to eq(403)
+      end
+
+      context "with a valid staff account" do
+        before do
+          sign_in(admin)
+        end
+
+        it "deletes the record" do
+          topic_id = published_page.topic_id
+
+          delete "/pub/by-topic/#{topic_id}.json"
+          expect(response).to be_successful
+          expect(PublishedPage.exists?(slug: published_page.slug)).to eq(false)
+
+          expect(UserHistory.exists?(
+            acting_user_id: admin.id,
+            action: UserHistory.actions[:page_unpublished],
+            topic_id: topic_id
+          )).to be(true)
+        end
+      end
+    end
+  end
+
+  context "when disabled" do
+    before do
+      SiteSetting.enable_page_publishing = false
+    end
+
+    it "returns 404 for any article" do
+      get published_page.path
+      expect(response.status).to eq(404)
+    end
+  end
+
+end