# Assert Gooder Supercharged assert replacement. Lua Library that replaces the default [assert](https://www.lua.org/manual/5.4/manual.html#pdf-assert) function with one that can emit improved error messages. The improved assert function parses the assert condition, inspects the state of the program and emits an improved error message. ## Example ```lua function f (a) ``` assert(type(a) == 'string') ``` end f(42) ``` Without [assert-gooder](index.html#), the above code would fail with the error message `assertion failed!`. With [assert-gooder](index.html#), it will fail with this error message: `assertion failed! bad argument #1 'a' to 'f' (string expected, but got number: 42)`, ## Motivation Assertions are useful to ensure internal consistency, when you're writing code in a hurry, but in Lua (and most other languages), these assert constructs never produce useful error messages, but rather unhelpful `assert failed!` errors and a stack trace. By making it a runtime library, instead of a "compile-time" rewrite, we gain flexibility. It's much easier to import a library, than restructuring then compile pipeline. It also means that we have access to runtime values, allowing even more helpful messages. ## Setup Download, and use `assert = require "assert-gooder"` to overwrite Lua's default assert with [assert-gooder](index.html#). - Author: Jon Michael Aanes (jonjmaa@gmail.com) ## Dependencies This project requires [PUC Lua 5.1](https://www.tecgraf.puc-rio.br/lua/mirror/versions.html#5.1) or [LuaJIT](https://luajit.org/luajit.html). Newer versions of PUC Lua are not supported. This project does not have any library requirements 😎 ## Contributing Feel free to submit pull requests. Please follow the [Code Conventions](CONVENTIONS.md) when doing so. ## License ``` MIT License Copyright (c) 2017-2025 Jon Michael Aanes Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. ```