Add tests to `testing/` and `std/` with Elsa.tests

[littledivy]

Add tests for all the js/ts files inside testing/ and std/

The test file should be named in the pattern *_test.js for elsa to identify it as a test file.

Example:

// some_test.js
import { eq } from "./utils.ts";

Elsa.tests({
  "test mode == `test`": function () {
    eq(Elsa.mode, "test");
  },
});

and run ./elsa test

Marking as a good first issue as anyone with Deno.test experience can give it a try 😄

[sidntrivedi]

Hey @littledivy, is this issue resolved? If not, would like to give it a go. Thanks :)

[littledivy]

tests for testing/ have been added. std tests are pending - feel free to give it a try