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toContain()

The toContain() method asserts that an array contains a specific item or a string contains a substring.

Syntax

JavaScript 
expect(actual).toContain(expected);
expect(actual).not.toContain(expected);

Parameters

ParameterTypeDescription
expectedanyThe value to search for

Returns

TypeDescription
voidNo return value

Description

The toContain() method checks if:

  • An array contains a specific element (using includes())
  • A string contains a substring (using includes())

For arrays, it uses strict equality (===) to match elements. For more complex object matching in arrays, use toContainEqual().

Usage

JavaScript 
import { expect } from 'https://jslib.k6.io/k6-testing/0.5.0/index.js';

export default function () {
  const numbers = [1, 2, 3, 4, 5];
  expect(numbers).toContain(3);
  expect(numbers).not.toContain(6);

  const fruits = ['apple', 'banana', 'orange'];
  expect(fruits).toContain('banana');
  expect(fruits).not.toContain('grape');
}