Add testing-guide.md to document testing best practices

[victor-yanev]

Problem

To ensure consistency and quality in our testing approach, we need to create a comprehensive testing-guide.md document. This guide will serve as a reference for all contributors to understand and implement best practices in writing tests for our project.

Benefits

• Consistency: Ensures all contributors follow the same testing practices, leading to more consistent and reliable tests.
• Quality: Improves the overall quality of the codebase by promoting thorough and effective testing.
• Onboarding: Eases the onboarding process for new developers by providing a clear and structured guide to testing.
• Efficiency: Saves time by providing ready-to-use examples and reducing the learning curve for writing tests.

Objectives

1. Document Testing Strategies: Outline the overall testing strategy, including unit tests, integration tests, and end-to-end tests.
2. Environment Setup: Provide detailed instructions on setting up the testing environment, including necessary dependencies and configurations.
3. Test Writing Guidelines: Offer guidelines on how to write effective and maintainable tests, including naming conventions, structuring test cases, and using assertions.
4. Utilizing Helper Methods: Explain the usage of helper methods such as overrideEnvs, withOverriddenEnvs, useInMemoryRedisServer, startRedisInMemoryServer, and stopRedisInMemoryServer. Include examples and scenarios where these methods should be used.
5. Common Pitfalls: Highlight common mistakes and pitfalls in writing tests and how to avoid them.
6. Code Examples: Provide code examples and templates that developers can use as a starting point for writing their tests.
7. Continuous Integration: Describe how tests are integrated into the CI/CD pipeline and the importance of maintaining a green build and isolating failing test cases.

Action Items

• Create a new testing-guide.md file in the root directory of the project.
• Populate the guide with the outlined sections and content.
• Review and refine the guide with input from senior developers and the QA team.
• Communicate the availability of the guide to all contributors and encourage its usage.

By implementing this guide, we aim to foster a culture of quality and reliability in our development process, ensuring that all code changes are thoroughly tested and validated.