test: Add Tests for /api/credit/lines and /api/credit/lines/:id Endpoints (#29)

[Bug-Hunter-X]

Overview

Adds focused integration tests for credit line list/detail endpoints, including empty-list behavior, success responses, and not-found responses.
Also adds minimal route error-path tests to ensure the credit route file meets the required route-level coverage threshold.

Closes #29

Changes

Credit Route Endpoint Tests

• [ADD] src/test/creditLinesEndpoints.test.ts
  • Added tests for GET /api/credit/lines:
  • Returns 200 with empty list when store is empty.
  • Returns all lines for success/future growth cases.
  • Returns JSON content-type.
  • Added tests for GET /api/credit/lines/:id:
  • Returns 200 with full credit line payload for known ID.
  • Returns 404 with consistent not-found format for unknown ID.
  • Returns JSON content-type on not-found response.

Route Coverage Support

• [ADD] src/test/creditRouteErrorHandling.test.ts
  • Added minimal tests for unexpected error handling in credit route POST handlers to cover 500 fallback branches.
  • Ensures route file reaches required coverage threshold without changing endpoint behavior.

Documentation

• [MODIFY] README.md
  • Added a testing note for running credit lines endpoint tests.

Tooling / Test Dependencies

• [MODIFY] package.json
  • Added supertest and @types/supertest under dev dependencies.
• [MODIFY] package-lock.json
  • Lockfile updates for added test dependencies.

How to Run Tests

npm test -- src/__test__/creditLinesEndpoints.test.ts src/__test__/creditRouteErrorHandling.test.ts

# Route coverage for credit route:
npx vitest run src/__test__/creditLinesEndpoints.test.ts src/__test__/creditRouteErrorHandling.test.ts --coverage --coverage.include=src/routes/credit.ts --coverage.reporter=text

Verification Results

Requirement	Status
Tests for /api/credit/lines	Done
Tests for /api/credit/lines/:id	Done
Empty list behavior covered	Done
Not-found behavior covered	Done
Success cases covered	Done
Route coverage >=95%	Done (100% for src/routes/credit.ts)
Documentation updated	Done

Verification Evidence

• npm test -- src/__test__/creditLinesEndpoints.test.ts src/__test__/creditRouteErrorHandling.test.ts
  • Passed: 2 test files, 14 tests.

• npx vitest run src/__test__/creditLinesEndpoints.test.ts src/__test__/creditRouteErrorHandling.test.ts --coverage --coverage.include=src/routes/credit.ts --coverage.reporter=text
  • src/routes/credit.ts: 100% statements, 100% branches, 100% functions, 100% lines.

[Bug-Hunter-X]

@greatest0fallt1me rei=view and merge sir

[greatest0fallt1me]

@Bug-Hunter-X Can you resolve the conflicts?

[Bug-Hunter-X]

@Bug-Hunter-X Can you resolve the conflicts?

DONE boss