Node.JS Basic testing

Task goal:

Write unit tests for code, provided in file index.ts.

How to use:

• use cli script 'npm install',
• use cli script 'npm run test' of 'npm run test:verbose ${testFilePath}',

Implemented tests:

1. Simple tests
2. Table tests
3. Error handling & async
4. Testing class
5. Partial mocking
6. Mocking Node.js API
7. Mocking library API
8. Snapshot testing

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Task: basic testing