Assertion

Error constructor for test and validation frameworks that implements standardized AssertionError specification.

Assertion Library for Browser and Node.JS

Format errors to display a diff between the actual and expected

Allow parsing of the module assertion attributes in the import statement

Support for import assertions in acorn

Pass two numbers, get a regex-compatible source string for matching ranges. Validated against more than 2.78 million test assertions.

Validate XML, Parse XML, Build XML without C/C++ based libraries

Extra assertions on top of node's assert module

Type check values

minimalistic-assert ===

BDD/TDD assertion library for node.js and the browser. Test framework agnostic.

A tiny invariant function

The assert module from Node.js, for the browser.

String validation and sanitization

simple, flexible, fun test framework

JavaScript test spies, stubs and mocks.

Featherweight assert module

Lazy assertions without performance penalty

Do things in development and nothing otherwise

[](https://github.com/mmkal/expect-type/actions/workflows/ci.yml)  [![X (formerly Twitter) Follow](https://img.shields.io/twitte

flow typed nullthrows

TypeScript implementation of invariant(condition, message)

A little library for asserting types and values, with zero dependencies.

typesafe assertion library for TypeScript 3.7+

Yet another JavaScript assertion/invariant library.

uvu is an extremely fast and lightweight test runner for Node.js and the browser

assert with status codes

assertion renderer for power-assert context

Helpers for asserting that a JavaScript environment supports certain features necessary for the operation of the Solana JavaScript SDK

A simple and composable way to validate data in JavaScript (and TypeScript).

test framework agnostic BDD-style assertions

Type assertions aka less-broken `typeof`

TypeScript definitions for http-assert

Adaptation of react-addons-shallow-compare, for independent usage

Useful utilities for working with Uint8Array (and Buffer)

Helper function for exhaustive checks of discriminated unions in TypeScript

Next-gen browser and mobile automation test framework for Node.js

JavaScript Testing utilities for React

Hook and modify stdout and stderr

Additional Jest matchers

Extends Chai with assertions about promises.

Function argument validation for humans

JavaScript Testing utilities for React

WebdriverIO Assertion Library

JavaScript Testing utilities for React

Better assertions for node, reporting the expr, filename, lineno etc

Precondition checking utilities.

Extends Chai with assertions for the Sinon.JS mocking framework.

A tiny javascript type testing tool

Disallow type assertions in TypeScript code