Configured markdownlint to load custom config 🪇

[01taylop]

Details

What have you changed?

• 📑 Configured markdownlint to load custom config, defaulting to config defined by Lint Pilot.
• 🗞️ Installed and configured @rollup/plugin-replace.
• 🃏 Added a custom Jest matcher, toHaveBeenCalledOnceWith.
• 🌟 Improved unit tests, TypeScript types, utility functions, and global options such as debug.

Why are you making these changes?

• 🗞️ The @rollup/plugin-replace plugin means we can have conditional logic, such as if (process.env.NODE_ENV === 'development') { ... }, which can be removed from the bundle when compiling the module.
• 🃏 In many tests we assert that a mock is called once and with the correct arguments. A primary use-case is when asserting console.log to ensure there are no unexpected logs. This custom matcher combines two assertions into one which helps keep the tests cleaner, leaner, and therefore easier to read and maintain.
• 🌟 Improvements:
  • The unit tests are more concise, clearer, and more maintainable.
  • The TypeScript types are defined clearly in the most relevant files for their usage.
  • The utils such as colourLog has been improved and can now be used for all logging, including errors.
  • The option "debug" is now stored as a global so it can be accessed anywhere without needing to pass it around in each function.