Add specs for BackupPolicy (mastodon#9576)

Author: ysksn

spec/policies/backup_policy_spec.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+require 'pundit/rspec'
+
+RSpec.describe BackupPolicy do
+  let(:subject) { described_class }
+  let(:john)    { Fabricate(:user).account }
+
+  permissions :create? do
+    context 'not user_signed_in?' do
+      it 'denies' do
+        expect(subject).to_not permit(nil, Backup)
+      end
+    end
+
+    context 'user_signed_in?' do
+      context 'no backups' do
+        it 'permits' do
+          expect(subject).to permit(john, Backup)
+        end
+      end
+
+      context 'backups are too old' do
+        it 'permits' do
+          travel(-8.days) do
+            Fabricate(:backup, user: john.user)
+          end
+
+          expect(subject).to permit(john, Backup)
+        end
+      end
+
+      context 'backups are newer' do
+        it 'denies' do
+          travel(-3.days) do
+            Fabricate(:backup, user: john.user)
+          end
+
+          expect(subject).to_not permit(john, Backup)
+        end
+      end
+    end
+  end
+end