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toBeInstanceOf()
The toBeInstanceOf() method asserts that a value is an instance of a specific class or constructor function.
Syntax
expect(actual).toBeInstanceOf(expected);
expect(actual).not.toBeInstanceOf(expected);Parameters
Returns
Description
The toBeInstanceOf() method uses the instanceof operator to check if the actual value is an instance of the expected constructor or class. It checks the prototype chain to determine if the constructor function appears anywhere in the object’s prototype chain.
Usage
import http from 'k6/http';
import { expect } from 'https://jslib.k6.io/k6-testing/0.6.1/index.js';
class User {
constructor(name) {
this.name = name;
}
}
export default function () {
const response = http.get('https://quickpizza.grafana.com/');
// Check response object types
expect(response).toBeInstanceOf(Object);
expect(response.headers).toBeInstanceOf(Object);
// Check built-in types
expect([1, 2, 3]).toBeInstanceOf(Array);
expect(new Date()).toBeInstanceOf(Date);
// Check custom classes
const user = new User('John');
expect(user).toBeInstanceOf(User);
expect(user).not.toBeInstanceOf(Array);
}
