Add more tests for self-destruct mode (#30374)

spec/helpers/self_destruct_helper_spec.rb

@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe SelfDestructHelper do
+  describe 'self_destruct?' do
+    context 'when SELF_DESTRUCT is unset' do
+      it 'returns false' do
+        expect(helper.self_destruct?).to be false
+      end
+    end
+
+    context 'when SELF_DESTRUCT is set to an invalid value' do
+      around do |example|
+        ClimateControl.modify SELF_DESTRUCT: 'true' do
+          example.run
+        end
+      end
+
+      it 'returns false' do
+        expect(helper.self_destruct?).to be false
+      end
+    end
+
+    context 'when SELF_DESTRUCT is set to value signed for the wrong purpose' do
+      around do |example|
+        ClimateControl.modify(
+          SELF_DESTRUCT: Rails.application.message_verifier('foo').generate('example.com'),
+          LOCAL_DOMAIN: 'example.com'
+        ) do
+          example.run
+        end
+      end
+
+      it 'returns false' do
+        expect(helper.self_destruct?).to be false
+      end
+    end
+
+    context 'when SELF_DESTRUCT is set to value signed for the wrong domain' do
+      around do |example|
+        ClimateControl.modify(
+          SELF_DESTRUCT: Rails.application.message_verifier('self-destruct').generate('foo.com'),
+          LOCAL_DOMAIN: 'example.com'
+        ) do
+          example.run
+        end
+      end
+
+      it 'returns false' do
+        expect(helper.self_destruct?).to be false
+      end
+    end
+
+    context 'when SELF_DESTRUCT is set to a correctly-signed value' do
+      around do |example|
+        ClimateControl.modify(
+          SELF_DESTRUCT: Rails.application.message_verifier('self-destruct').generate('example.com'),
+          LOCAL_DOMAIN: 'example.com'
+        ) do
+          example.run
+        end
+      end
+
+      it 'returns true' do
+        expect(helper.self_destruct?).to be true
+      end
+    end
+  end
+end