Adding tests should be extremely easy. Otherwise you’ll just skip it.

x9 provides three ways of creating tests:

• x9.test: testing with Dragon DNA via x9.test
  • this is the recommended way of writing tests. It provides a few new features such as
• block tests: block form syntax for inline testing
  • similar to playgrounds, they are extremely convenient and concise
• jest/mocha: (soon)
  • use test, describe, it, expect, etc
  • useful if you’re migrating an existing codebase and you don’t want to rewrite your tests

Mini Tests (or Test Blocks)

If you use expect within a playground, it becomes a test. You’ll see its color change in the IDE.

function sum(a, b) {
  return a + b;
}

{
  expect(sum(1, 2)).toBe(3);
}

• If automatic detection fails, you can explicitly transform a playground into a test by adding a // x9.test comment (and // x9.test=false if it fails the other way)

Async/Await

You can use await at the top level (within the block). The containing block will be automatically treated as an async function

{  expect(await sum(1, 2)).toBe(3);}

Proposal: Terse Assertion Syntax

Experimental: When using the Block form you also get some syntactic sugar.

{  // x9.test  sum(1, 2) === 3; // expect(1,2).toBe(3)  sum(1, 2) < 10; // expect(1,2).toBeLessThan(10)}

The goal of this syntax is twofold:

1. It makes writing basic tests even easier (the ultimate goal is to remove all boundaries so writing basic tests becomes part of your normal workflow, with zero overhad)
2. This terse syntax results in highly readable tests that can serve as documentation. For a related idea, see Python doctests

Notes:

• Only top-level (direct children of the block) binary expressions statements with a boolean operator (==, ===, !=, !==, >=, etc) are transformed.