Add API endpoint for fetching a brand

app/controllers/api/brands_controller.rb

@@ -0,0 +1,12 @@
+class Api::BrandsController < ApplicationController
+  def show
+    expires_in 5.minutes, public: true
+    render json: brand.as_json(only: %i[name slug])
+  end
+
+private
+
+  def brand
+    Brand.find_by!(id: params[:brand_id])
+  end
+end

config/routes.rb

@@ -299,6 +299,8 @@
       get "/:tag", to: "api/form_documents#show", as: :form_document, constraints: { tag: /draft|live|archived/ }
       get "/group", to: "api/form_documents#group", as: :form_group
     end
+
+    get "brands/:brand_id", to: "api/brands#show", as: :brand
   end
 
   get "/maintenance" => "errors#maintenance", as: :maintenance_page

spec/requests/api/brands_controller_spec.rb

@@ -0,0 +1,41 @@
+require "rails_helper"
+
+RSpec.describe Api::BrandsController, type: :request do
+  let(:headers) { { "ACCEPT": "application/json" } }
+
+  describe "#show" do
+    context "when the brand exists" do
+      let(:brand) { create :brand, name: "Golden Zephyr", slug: "golden-zephyr" }
+
+      before do
+        get "/api/v2/brands/#{brand.id}", headers:
+      end
+
+      it "returns http success" do
+        expect(response).to have_http_status(:success)
+      end
+
+      it "returns the brand configuration" do
+        expect(response.parsed_body).to eq({
+          "name" => "Golden Zephyr",
+          "slug" => "golden-zephyr",
+        })
+      end
+
+      it "sets the response to be cached for 5 minutes" do
+        expect(response.headers["Cache-Control"]).to eq("max-age=300, public")
+      end
+    end
+
+    context "when the brand does not exist" do
+      before do
+        get "/api/v2/brands/0", headers:
+      end
+
+      it "returns http not found" do
+        expect(response).to have_http_status(:not_found)
+        expect(response.headers["Content-Type"]).to eq("application/json; charset=utf-8")
+      end
+    end
+  end
+end