Make chai.js and SinonJS compatible with testing framework and add instructions how to use it

chai.js and Sinon.JS are very popular testing libraries that run both in Node and browser.

Since they can be run in browser it should be a low hanging fruit to make them work in Deno and I believe it would be very valuable to add “first-class” instructions to testing/README.md how they could be used with Deno’s built-in testing (deno test).

CC @keithamus

[bartlomieju]

Are you facing any challenges…

Mostly motivation 😂. Deno is pleasurable to work with although it can be prickly with regard to imports and the .ts extension which Node+TypeScript doesn’t like, but Deno requires. I’m not sure if there is good tooling to help manage the difference in dependency APIs?

Keith I noticed that chai already has browser support; I’m willing to guess that it should just work in Deno without any changes. Maybe the only thing you want to do is link that output to https://deno.land/x/ to make it more discoverable for Deno users?

[kt3k]

addressed in #1334. Thank you @cmorten for the work!