Replace nil specs with Sorbet type checks in TestDataHelpers

[stefan-burke]

Summary

• Converted TestDataHelpers module to use Sorbet strict typing
• Added Sorbet signatures to all helper methods for better type safety
• Removed redundant RSpec tests that checked for nil handling, relying on Sorbet instead

Changes

Type System

• Changed # typed: false to # typed: strict in lib/test_data_helpers.rb
• Added extend T::Sig to enable Sorbet signatures
• Added sig annotations for all public methods in TestDataHelpers:
  • british_phone_number returns String
  • british_postcode returns String
  • british_address returns String
  • british_city returns String
  • british_company_name takes a String and returns a String

Tests

• Removed the spec context that tested british_company_name with a nil base name, as Sorbet typing enforces non-nil String input

Test plan

• Existing tests for TestDataHelpers pass without errors
• Confirmed no regressions by running full test suite

This change improves code robustness by leveraging Sorbet's static type checking and removes unnecessary runtime nil checks in tests.

🌿 Generated by Terry

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📎 Task: https://www.terragonlabs.com/task/f979d69b-f156-4b6f-a0e4-671badd73cc4