Add model TermsOfServiceFile

We want to enable instance managers to upload TOS files.

I also added the rails_helper which is a new convention. It can contain
more Rails specific configuration we currently have in the spec_helper.

app/models/terms_of_service_file.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class TermsOfServiceFile < ApplicationRecord
+  # The most recently uploaded file is the current one.
+  def self.current
+    order(:id).last
+  end
+end

db/migrate/20210415015550_create_terms_of_service_files.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class CreateTermsOfServiceFiles < ActiveRecord::Migration[5.0]
+  def change
+    # rubocop:disable Style/SymbolProc
+    create_table :terms_of_service_files do |t|
+      t.timestamps
+    end
+    # rubocop:enable Style/SymbolProc
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2021_04_14_171109) do
+ActiveRecord::Schema.define(version: 2021_04_15_015550) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -1145,6 +1145,11 @@ ActiveRecord::Schema.define(version: 2021_04_14_171109) do
     t.index ["name"], name: "index_tags_on_name", unique: true
   end
 
+  create_table "terms_of_service_files", force: :cascade do |t|
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
   create_table "variant_overrides", force: :cascade do |t|
     t.integer "variant_id", null: false
     t.integer "hub_id", null: false

spec/models/terms_of_service_file_spec.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe TermsOfServiceFile do
+  describe ".current" do
+    it "returns nil" do
+      expect(TermsOfServiceFile.current).to be_nil
+    end
+
+    it "returns the last one" do
+      existing = [
+        TermsOfServiceFile.create!,
+        TermsOfServiceFile.create!,
+      ]
+
+      expect(TermsOfServiceFile.current).to eq existing.last
+    end
+  end
+end

spec/rails_helper.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require 'spec_helper'