| <p align=center> |
| AssertionError and AssertionResult classes. |
| </p> |
|
|
| <p align=center> |
| <a href="https://github.com/chaijs/assertion-error/actions"> |
| <img |
| alt="build:?" |
| src="https://github.com/chaijs/assertion-error/actions/workflows/nodejs.yml/badge.svg" |
| /> |
| </a><a href="https://www.npmjs.com/package/assertion-error"> |
| <img |
| alt="downloads:?" |
| src="https://img.shields.io/npm/dm/assertion-error.svg" |
| /> |
| </a><a href=""> |
| <img |
| alt="devDependencies:none" |
| src="https://img.shields.io/badge/dependencies-none-brightgreen" |
| /> |
| </a> |
| </p> |
| |
| ## What is AssertionError? |
|
|
| Assertion Error is a module that contains two classes: `AssertionError`, which |
| is an instance of an `Error`, and `AssertionResult` which is not an instance of |
| Error. |
|
|
| These can be useful for returning from a function - if the function "succeeds" |
| return an `AssertionResult` and if the function fails return (or throw) an |
| `AssertionError`. |
|
|
| Both `AssertionError` and `AssertionResult` implement the `Result` interface: |
|
|
| ```typescript |
| interface Result { |
| name: "AssertionError" | "AssertionResult"; |
| ok: boolean; |
| toJSON(...args: unknown[]): Record<string, unknown>; |
| } |
| ``` |
|
|
| So if a function returns `AssertionResult | AssertionError` it is easy to check |
| _which_ one is returned by checking either `.name` or `.ok`, or check |
| `instanceof Error`. |
|
|
| ## Installation |
|
|
| ### Node.js |
|
|
| `assertion-error` is available on [npm](http://npmjs.org). |
|
|
| ``` |
| $ npm install --save assertion-error |
| ``` |
|
|
| ### Deno |
|
|
| `assertion_error` is available on |
| [Deno.land](https://deno.land/x/assertion_error) |
|
|
| ```typescript |
| import { |
| AssertionError, |
| AssertionResult, |
| } from "https://deno.land/x/assertion_error@2.0.0/mod.ts"; |
| ``` |
|
|
