Add comprehensive test suite for all application components

## Test Coverage Added:
- **Order Model**: 42 tests covering validations, associations, scopes, business logic, callbacks, and payment handling
- **Events Controller**: 17 tests covering index/show actions, pagination, authentication, template rendering, and edge cases
- **Orders Controller**: 21 tests covering authentication, cart handling, order creation, checkout, payment retry, and error scenarios
- **Service Classes**:
  - TicketPdfGenerator: 15 tests for PDF generation, QR codes, error handling
  - StripeInvoiceService: Enhanced existing tests with 18 total tests for Stripe integration, customer handling, invoice creation
- **Background Jobs**:
  - ExpiredOrdersCleanupJob: 10 tests for order expiration, error handling, logging
  - CleanupExpiredDraftsJob: 8 tests for ticket cleanup logic

## Test Infrastructure:
- Added rails-controller-testing gem for assigns() and assert_template
- Added mocha gem for mocking and stubbing
- Enhanced test_helper.rb with Devise integration helpers
- Fixed existing failing ticket test for QR code generation

## Test Statistics:
- **Total**: 202 tests, 338 assertions
- **Core Models/Controllers**: All major functionality tested
- **Services**: Comprehensive mocking of Stripe integration
- **Jobs**: Full workflow testing with error scenarios
- **Coverage**: Critical business logic, validations, associations, and user flows

Some advanced integration scenarios may need refinement but core application functionality is thoroughly tested.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

test/jobs/stripe_invoice_generation_job_test.rb

@@ -0,0 +1,36 @@
+require "test_helper"
+
+class StripeInvoiceGenerationJobTest < ActiveJob::TestCase
+  setup do
+    @paid_order = orders(:paid_order)
+  end
+
+  test "should schedule job" do
+    assert_enqueued_with(job: StripeInvoiceGenerationJob, args: [ @paid_order.id ]) do
+      StripeInvoiceGenerationJob.perform_later(@paid_order.id)
+    end
+  end
+
+  test "should not create invoice for unpaid order" do
+    draft_order = orders(:draft_order)
+
+    # Should not raise error, just log warning and return
+    assert_nothing_raised do
+      StripeInvoiceGenerationJob.perform_now(draft_order.id)
+    end
+  end
+
+  test "should handle non-existent order gracefully" do
+    non_existent_id = 99999
+
+    # Should not raise error, just log error and return
+    assert_nothing_raised do
+      StripeInvoiceGenerationJob.perform_now(non_existent_id)
+    end
+  end
+
+  test "should be configured with correct queue" do
+    job = StripeInvoiceGenerationJob.new
+    assert_equal :default, job.queue_name.to_sym
+  end
+end