Ist NPM | npm.io

ist

This is a tiny assertion library (in the same space as require("assert")) that is only a handful of lines, and exports a simple API.

var ist = require("ist")

ist([] instanceof Array) // Assert that the argument is truthy
ist(1 + 1, 2)            // Assert that two values are the same
ist(1 + 1, 3, "<")       // Assert that 2 is less than 3
ist(a, b, myCompareFunc) // Pass an arbitrary compare function

ist.throws(function() { undefined.prop }) // Ensure something throws

ist(value)

Throws a exception of class ist.Failure when value is falsy.

ist(a, b, compare)

Compares a and b, and throws an ist.Failure if the comparison fails. compare defaults to ==, but you can pass a string that corresponds to a JavaScript comparison operator, or a custom function, to compare in a different way.

ist.throws(f, matches)

Ensure that calling f throws an exception, and optionally test whether the exception matches your expectation. matches may be a regexp, which is matched against the exception's message property, a string, which should be the same as the message, or a function that takes an exception and returns a boolean.