Add Unit Tests

[Kokonutic]

This PR adds comprehensive unit and integration tests for the backend API server, targeting user authentication, trip planning, and chat functionality. The tests are implemented using Jest and Supertest with proper mocking of external dependencies.

Key changes include:

• Updated Jest and Supertest to latest patch versions for improved testing capabilities
• Added comprehensive test coverage for user authentication flows (signup, login, profile management, password changes)
• Added test coverage for trip planning API with OpenAI service mocking to validate request handling and response generation

PR CHECKLIST

• My code follows the style guidelines of this project (variable naming, commenting, copyright, etc.)
• I have performed a self-review of my code
• Changes are clearly highlighted and easy to understand
• I have commented my code, particularly in hard-to-understand areas
• I have meaningful commit messages that explain what was changed/committed
• I have built and locally tested my changes
• My changes generate no new errors or regressions (pending verification)
• I have made corresponding changes to the documentation OR this is N/A
• Documentation accurately reflects the current state of the project OR this is N/A
• I have added tests that prove my fix is effective or that my feature works OR this is N/A
• New and existing unit tests pass locally with my changes OR this is N/A
• Any dependent changes have been merged and published in downstream modules OR this is N/A
• All links are working and correct OR this is N/A
• Spelling and grammar are correct
• I have added the "READY FOR REVIEWS" tag when this PR is ready for reviews

[Copilot]

Pull Request Overview

This PR adds comprehensive unit and integration tests for the backend API server, targeting user authentication, trip planning, and chat functionality. The tests are implemented using Jest and Supertest with proper mocking of external dependencies.

Key changes include:

• Updated Jest and Supertest to latest patch versions for improved testing capabilities
• Added comprehensive test coverage for user authentication flows (signup, login, profile management, password changes)
• Added test coverage for trip planning API with OpenAI service mocking to validate request handling and response generation

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated no comments.

File	Description
package.json	Updated Jest and Supertest dependencies to latest patch versions
tests/user.test.js	Comprehensive user authentication API tests with database and auth service mocking
tests/plan.test.js	Trip planning API tests with OpenAI service mocking and validation
tests/chat.test.js	Chat/trip history API tests with database and image service mocking

Comments suppressed due to low confidence (3)

tests/user.test.js:85

• The test should expect a specific status code (201 for resource creation) rather than accepting multiple possible codes. This makes the test assertion less precise.

      expect([200, 201]).toContain(res.statusCode);

tests/user.test.js:209

• The test should expect a specific status code (typically 200 or 204 for password updates) rather than accepting multiple possible codes. This makes the test assertion less precise.

      expect([200, 204]).toContain(res.statusCode);

tests/plan.test.js:77

• The test should have separate test cases for success (200) and failure (503) scenarios rather than accepting both status codes in a single assertion. This would provide better test coverage and clearer test intentions.

      expect([200, 503]).toContain(res.statusCode);

[Rongbin99]

LGTM