test: Add comprehensive tests for user promo operations

[RandomProgramm3r]

This commit introduces a suite of tests for the user-facing promo code functionality, ensuring robustness and correctness.
The new tests cover the following areas:

• Promo Code Activation:

  • Verification of activation logic, including success and failure scenarios for common and unique promos.
  • Edge cases such as inactive promos, targeting mismatches, and exhausted activation limits (max_count).
  • Checks to prevent users who are blocked by the anti-fraud service from activating promos.

• Promo Activation History:

  • Tests for the user's promo activation history endpoint.
  • Validation of the returned data and its order.
  • Pagination functionality (limit and offset).

• Anti-Fraud Service Integration:

  • Unit tests for the AntiFraudService to verify its caching behavior and resilience to external service failures.
  • Integration tests to confirm that the promo activation process correctly respects the anti-fraud service's verdicts, including delayed updates from the cache.