The Node.js assert API is simple and easy to use, but can be useful if a test suit like Jest is too much to your requirements at a certain moment. If it does not, throw an AssertionError.Īnd, if you need, just use the assert.fail() to throw a AssertionError with this message. Tests if the value of the expression is true. When the assertion is true, a AssertionError **is throw. ![]() "Deep" equality means that the enumerable "own" properties of child objects are recursively evaluated also by the following rules."Īssert.notDeepStrictEqual(actual, expected)īasically, the inverse of deepStrictEqual. "Tests for deep equality between the actual and expected parameters.Throw a AssertionError **if the values are equal.Īssert.notStrictEqual( 5, 10, "5 is equal to 10 ?") ĪepStrictEqual(actual, expected) We did our first test that will fail, but what is strictEqual? This function and others will be showed here.Īssert.strictEqual(actual, expected)Īssert.notStrictEqual(actual, expected) import assert from "assert" Īssert.strictEqual( 5, 10, "The values are not equal") //test if the values are equal console.log( "Ok") To verify the result, without fight against a Node.js error, it is possible to put the assertions inside a "try catch". The functions of the "assert" module throw an exception called AssertionError **when some tests failed, but it does nothing when it passes. To begin, you just import the module "assert" to your code import assert from "assert" Notice some function from this module are deprecated and others are under test, so I'll just introduce the stable ones.įor this tutorial, I'm using Node.js, version 15.6.0 and npm, version 6.14.11. To try this test approach in Node.js, we can use the " assert" module, what provide some basics functions to check your functions and methods. This practice became a software development process called TDD (Test-driven development), what consist basically in create a test before build the feature, let it fail, and build the code to pass this test, what do the code to be smaller and focused. where assert would throw an error if the condition were false.Testing are a way that you can do to verify if the features of your application are working correctly, either isolated or integrated. So you might do: assert(typeof argumentName = "string") You'd want to know if someone called that function with something that wasn't a string (without having a type checking layer like TypeScript or Flow). Suppose you had a function that was supposed to always accept a string. Usually assertions (as they're called) are used only in "testing" or "debug" builds and stripped out of production code. The usual meaning of an assert function is to throw an error if the expression passed into the function is false this is part of the general concept of assertion checking. ![]() (Browsers and other environments that offer a console implementing the Console API provide console.assert.) ![]() Perhaps you're using some library that provides one for instance, if you're using Node.js, perhaps you're using the assertion module. There is no standard assert in JavaScript itself.
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