test: add follower module tests

[hikmatazimzade]

🧪 Add Tests for Follower Module

Summary

This pull request introduces a new test suite for the follower module, located at tests/web/test_follower.py. These tests are designed to validate the follower's behavior in various scenarios, ensuring robustness and reliability.

Details

• Test Coverage: The suite includes tests for scenarios such as handling of leader updates, response to edge cases, and correct state transitions.
• Purpose: By covering these cases, we aim to detect regressions early and maintain the integrity of the follower's functionality.
• Integration: The tests are integrated into the existing testing framework and can be run using pytest or the project's make test command.

Testing Instructions

To run the tests locally:

pytest tests/web/test_follower.py

Or, to run the entire test suite:

make test

Notes

• All tests pass successfully in the current environment.
• No changes were made to the core application code; this PR strictly adds new tests.