Add tests for ai.js

[AnhChienVu]

Description

I have written some tests for ai.js file

Changes Made

There are 4 tests for ai.js:

• Return a parsed temperature properly
• Should throw error if parsed temperature is NaN type
• Should handle ouput file if options.output is provided
• Should throw error if initializeModel() function throws error

Testing Details

I have used the mocking function feature of Jest to mock the returned value from relative functions that are used inside ai.js

Impact

The test made sure that the current code for ai.js is covered 100%

Checklist

• Code compiles correctly
• Tests have been written and run
• Code adheres to the style guidelines
• Ready for review