@rbxts/expect

Test-agnostic assertion library for ROBLOX.

---

Demo

import { expect } from "@rbxts/expect";
import t from "@rbxts/t";

enum Sport {
  Basketball,
  Soccer,
  Football
}

expect(5).to.be.a.number().that.equals(5);

expect("Daymon").to.have.the.substring("day");
expect("Mom").to.be.a.string().that.has.a.sizeOf(3);

expect(new Vector3(1, 2, 3)).to.equal(new Vector3(1, 2, 3));
expect({
  name: "Daymon",
  age: 24
}).to.equal({
  name: "Daymon",
  age: 24
});

expect(Sport.Basketball).to.be.the.enum(Sport, "Basketball");
expect("Football").to.be.the.enum(Sport);

expect(1).to.be.anyOf([1, 2, 3]);

expect([]).to.be.empty();
expect([1,2,3]).to.include(1);
expect([1,2,3]).to.be.an.array();
expect([1,2,3]).to.be.an.arrayOf("number");
expect([1,2,3]).to.have.the.size(3);

expect({ name: "Daymon" }).to.be.an.object().but.not.an.array();

expect(new Vector3(1,2,3)).to.be.an.instanceOf("Vector3");
expect("string").to.be.a.typeOf(t.string);

Installation

Install expect with your preferred package manager.

npm

npm install @rbxts/expect

pnpm

pnpm add @rbxts/expect

yarn

yarn add @rbxts/expect

Overview

expect is a test-agnostic assertion library for ROBLOX, enabling assertions in tests or server-side code without test dependencies; with a focus on more descriptive failure messages.

expect also provides a variety of common matchers out of the box, with full support for adding your own.

Documentation

Quick Start

API Reference

Matchers

Extension Guides

Features

Common matchers

expect comes packages with common matchers that you'll find in most modern assertion libraries; that were previously missing from popular roblox libraries.

expect(1).to.be.anyOf([1, 2, 3]);
expect([]).to.be.empty();
expect([1,2,3]).to.include(1);

Chainable matchers

Matchers return themselves, so you can write long chainable checks on values.

expect([1,2,3]).to.be.an.array()
               .that.is.not.empty()
               .and.includes(1)
               .but.does.not.include(4)

Array support

In typescript, the distinction between an object and an array is pretty black and white, while in lua, this distinction is usually lost.

expect attempts to rectify this by providing a variety of helper methods for checking arrays- and ensuring failure outputs for array values are formatted correctly.

Expected '{"name": "Daymon"}' to be an array, but it had a non number key 'name' (string)

Expected '[1,2,3]' to be an array of type 'string', but there was an element that was a 'number'

Index: 1
Value: 1

Expected '[1,2]' to deep equal '[1]', but there were extra elements

Expected: '[1]'
Actual: '[1,2]'
Extra Elements: '[2]'

Enum support

expect comes with first-class support for user-defined enums.

Expected '5' (number) to be a valid enum of '(First | Second | Third)'

Expected 'Basketball' (enum/number) to be any of '["Football", "Soccer"'

Table property testing

With the power of proxies, you can perform checks on your tables- and get their paths populated in your failure messages.

Expected parent.cars to be empty, but it had 2 elements.

parent.cars: '["Tesla","Civic"]'

Descriptive failure messages

Get more out of your failure messages, no matter what you're checking.

Expected '{"name": "Daymon"}' to be an array, but it had a non number key 'name' (string)

Easy extensibility

Easily add your custom methods, or custom properties to use with expect.

You can even publish a library of them!

Deep equals

By taking advantage of the @rbxts/deep-equal library, expect has full support for comparing nested object and roblox data-types.

Test-agnostic

Since @rbxts/expect is test-agnostic, you can take full advantage of it outside of tests.

import { expect } from "@rbxts/expect";
import { remotes } from "./remotes";
import { saves } from "./saves";
import { pets } from "./data";

remotes.purchasePet.connect(async (player, petId) => {
  const data = saves.get(player);
  const pet = pets.get(petId);

  expect(data.money, "You don't have enough money!").to.be.gte(pet.cost);

  data.money -= pet.cost;
  data.pets.push(pet);

  data.save();

  return "Pet purchased!";
});

Getting Started

So you're ready to get started with expect!

You can either checkout our Quick Start guide, or jump straight into our API Reference.

Roadmap

• Add publishing for wally
• Add docs for lua usage
• Implement workflow for test coverage
• Add workflow for checking API diff and version bumping according to semver
• Add note in contributing about checking the api diff

Contributing

If you're interested in contributing to expect, give the CONTRIBUTING doc a read.

License

Apache 2.0