httpexpect - End-to-end HTTP and REST API testing for Go.

•    Go

Concise, declarative, and easy to use end-to-end HTTP and REST API testing for Go (golang).Basically, httpexpect is a set of chainable builders for HTTP requests and assertions for HTTP responses and payload, on top of net/http and several utility packages.

fluentassertions - Fluent Assertions is a set of

•    CSharp

Fluent Assertions is a set of .NET extension methods that allow you to more naturally specify the expected outcome of a TDD or BDD-style test. We currently use it in all our internal and client projects, and it is used in many open-source projects. It runs on .NET 4.0, 4.5, 4.6, CoreClr, .NET Native, Windows 8.1, Silverlight 5, Windows Phone 8.0 and UWP. It supports the unit test frameworks MSTest, MSTest2, NUnit, XUnit, MBUnit, Gallio, NSpec and MSpec.

enzyme - JavaScript Testing utilities for React

•    Javascript

Enzyme is a JavaScript Testing utility for React that makes it easier to assert, manipulate, and traverse your React Components' output.Enzyme's API is meant to be intuitive and flexible by mimicking jQuery's API for DOM manipulation and traversal.

assertj-core - AssertJ is a library providing easy to use rich typed assertions

•    Java

Rich and fluent assertions for testing for Java

silk - Markdown based document-driven RESTful API testing.

•    Go

Markdown based document-driven web API testing. (VIDEO) Watch the talk about Silk (with slides) or read about Silk in this blog post.

chai-as-promised - Extends Chai with assertions about promises.

•    Javascript

Chai as Promised extends Chai with a fluent language for asserting facts about promises. Notice: either return or notify(done) must be used with promise assertions. This can be a slight departure from the existing format of assertions being used on a project or by a team. Those other assertions are likely synchronous and thus do not require special handling.

chai - BDD / TDD assertion framework for node

•    Javascript

Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework. For more information or to download plugins, view the documentation.

Testify - A toolkit with common assertions and mocks that plays nicely with the standard library

•    Go

Go code (golang) set of packages that provide many tools for testifying that your code will behave as you intend. It supports Easy assertions, Mocking, Testing suite interfaces and functions.

Pester - Pester is the ubiquitous test and mock framework for PowerShell.

•    PowerShell

Pester is the ubiquitous test and mock framework for PowerShell. This code example lies a tiny bit, find it annotated and production ready here.

kotlintest - Powerful, elegant and flexible Kotlin test framework

•    Kotlin

KotlinTest comes with several testing styles so you can choose one that fits your needs. Matchers are extension methods and so your IDE will auto complete. See the full list of matchers or write your own.

karate - Test Automation Made Simple

•    Java

Karate is the only open-source tool to combine API test-automation, mocks, performance-testing and even UI automation into a single, unified framework. The BDD syntax popularized by Cucumber is language-neutral, and easy for even non-programmers. Powerful JSON & XML assertions are built-in, and you can run tests in parallel for speed.

karate - Test Automation Made Simple

•    Java

Karate is the only open-source tool to combine API test-automation, mocks, performance-testing and even UI automation into a single, unified framework. The BDD syntax popularized by Cucumber is language-neutral, and easy for even non-programmers. Assertions and HTML reports are built-in, and you can run tests in parallel for speed.

gock - HTTP traffic mocking and expectations made easy for Go ༼ʘ̚ل͜ʘ̚༽

•    Go

Versatile HTTP mocking made easy in Go.Heavily inspired by nock. See also its Python port, pook.

Jasmine-Matchers - A huge library of test matchers for Jasmine and Jest.

•    Javascript

A huge library of test matchers for a range of common use-cases, compatible with all versions of Jasmine and Jest. Custom Matchers make tests easier to read and produce relevant and useful messages when they fail.

jest-extended - Additional Jest matchers 🃏💪

•    Javascript

Jest is an amazing test runner and has some awesome assertion APIs built in by default. However there are times when having more specific matchers (assertions) would be far more convenient. If you've come here to help contribute - Thanks! Take a look at the contributing docs as a way of getting started.

quicktest - Quick helpers for testing Go applications

•    Go

Package quicktest provides a collection of Go helpers for writing tests. An assertion looks like this, where qt.Equals could be replaced by any available checker. If the assertion fails, the underlying Fatal method is called to describe the error and abort the test.

Jolt.NET : Productivity Libraries for the .NET Framework

•    DotNet

Inspired by the Boost C++ libraries, Jolt.NET aims to complement the .NET Base Class Library (BCL) and .NET Framework with algorithms, data structures, and general productivity tools. It is the hope of the authors that Jolt.NET features will one day be represented in .NET.

Fluent Assertions

Fluent interface for writing .NET unit test assertions with more clarity than the traditional assertion syntax such as offered by MSTest, NUnit or XUnit.

Assertion.NUnit

•    DotNet

NUnit test helper class. Traditionally NUnit stops test on the first check failure. But sometimes subsequent rules check may helps with bug location.

truss - Assertions API for Clojure/Script

•    Clojure

Or: A lightweight alternative to static typing, clojure.spec, core.typed, @plumatic/schema, etc.Truss is a micro library for Clojure/Script that provides fast, flexible runtime condition assertions with great error messages. It can be used to get many of the most important benefits of static/gradual typing without the usual rigidity or onboarding costs.