Introduction to assert-plus

assert-plus is a simple assertion library for JavaScript, designed to provide a familiar API for testing and validating inputs in your applications. It is lightweight, performant, and easy to use. In this article, we will delve into the various APIs provided by assert-plus with code snippets and demonstrate how to utilize them effectively in your projects.

APIs and Examples

assert.bool(value, [message])

Ensures that value is a boolean.

const assert = require('assert-plus');
assert.bool(true); // Pass
assert.bool('not a boolean'); // Throws an AssertionError

assert.number(value, [message])

Validates that value is a number.

const assert = require('assert-plus');
assert.number(42); // Pass
assert.number('a string'); // Throws an AssertionError

assert.string(value, [message])

Checks if value is a string.

const assert = require('assert-plus');
assert.string('Hello World'); // Pass
assert.string(100); // Throws an AssertionError

assert.array(value, [message])

Validates that value is an array.

const assert = require('assert-plus');
assert.array([1, 2, 3]); // Pass
assert.array('not an array'); // Throws an AssertionError

assert.object(value, [message])

Ensures that value is an object.

const assert = require('assert-plus');
assert.object({ key: 'value' }); // Pass
assert.object(null); // Throws an AssertionError

App Example Using assert-plus

Now, let’s see a complete example of a Node.js application using assert-plus for input validation:

const assert = require('assert-plus');

// Example function to add a user
function addUser(user) {
   assert.object(user, 'user must be an object');
   assert.string(user.name, 'user name must be a string');
   assert.number(user.age, 'user age must be a number');
   assert.bool(user.active, 'user active must be a boolean');
  
   // proceed with adding user logic
   console.log('User added:', user);
}

// Example data
const newUser = {
   name: 'John Doe',
   age: 30,
   active: true
};

// Calling the addUser function
addUser(newUser);

In this example, we are adding a new user and validating that the user object has the correct data types for its properties using assert-plus APIs.

Note: The above example demonstrates a typical use case for input validation in Node.js applications.

By incorporating assert-plus into your projects, you can ensure robust input validation and improve the reliability of your code. Make sure to configure appropriate error handling and logging mechanisms to capture and respond to assertion errors in a controlled manner.

Explore more about assert-plus and its useful APIs in the official documentation to further enhance your testing strategies.

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