Refactor Kitty completely

[avborup]

Goals

I had a few main goals with this refactor:

• Improve the code quality to make it more readable, extendable, and maintainable
• Add some sort of integration tests to ensure that core functionality works
• Improve error messages and ability to diagnose bugs
• Fix bugs caused by the new Kattis UI update (which broke web scraping)

My main motivation for the refactor is that I feel like I have improved a lot at Rust in the past two years - and I wanted to apply that to kitty. As you can see, the first thing I did was remove all the code in the project so I could go through it, slowly adding/rewriting everything step by step.

What's changed?

As for what has actually changed in the code, this list can be seen as a rough summary:

• The CLI is now handled structopt-style with clap's derive macros. This makes handling of arguments more type-safe, and the CLI definition file is now far more readable.
• Everything is passed via arguments to functions, getting rid of the global lazy_static config object. The new App type is central here.
• Use eyre for error handling, heavily utilising wrap_err (analagous to anyhow's context, if you're familiar with that) to provide specific error messages. Combined with --verbose showing a backtrace, this allows for tracking down a problem more easily.
• Add integration tests that make sure that the most important happy and unhappy paths have the expected side effects and terminal output.
• macOS ARM now also receives a prebuilt binary for each new release (aarch64-apple-darwin)
• The history and random commands have been removed. These commands were seemingly not used often, and it streamlines the purpose of kitty a bit more. If there is a need for them, we can add them back down the line.

Subcommand progress

Tracks how many of the current subcommands have been refactored/reintroduced.

• config
• get
• help
• history
• langs
• open
• random
• submit
• test
• update

[avborup]

Task failed successfully:

Edit: has been fixed

[JoachimBorup]

Submitting a Java solution produces the following behaviour:

$ kitty submit addingwords -y
Problem:  addingwords
Language: Java
File:     Addingwords.java
Error: Failed to find submission ID in response from Kattis. Received: No mainclass set.