jest.ts

/*
 * Copyright (c) 2020, salesforce.com, inc.
 * All rights reserved.
 * SPDX-License-Identifier: BSD-3-Clause
 * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/BSD-3-Clause
 */

import { assertAccessible } from '@sa11y/assert';
import { A11yConfig, extended } from '@sa11y/preset-rules';
import { matcherHint } from 'jest-matcher-utils';

export const matcherHintMsg = `expected document to have no accessibility violations but found following issues: `;

// Type def for custom jest a11y matcher toBeAccessible
// Ref: https://jestjs.io/docs/en/expect.html#expectextendmatchers
declare global {
    // eslint-disable-next-line @typescript-eslint/no-namespace
    namespace jest {
        interface Matchers<R> {
            toBeAccessible(config?: A11yConfig): Promise<CustomMatcherResult>;
            toBeAccessibleWith(config: A11yConfig): Promise<CustomMatcherResult>;
        }
    }
}

/**
 * Jest expect matcher to check DOM for accessibility issues
 * @param receivedDom - DOM to be tested for accessibility
 * @param config - A11yConfig to be used to test for accessibility. Defaults to extended.
 */
export async function toBeAccessible(
    receivedDom: Document = document,
    config: A11yConfig = extended
): Promise<jest.CustomMatcherResult> {
    let isAccessible = true;
    let a11yViolations = '';

    try {
        await assertAccessible(receivedDom, config);
    } catch (e) {
        isAccessible = false;
        a11yViolations = e;
    }
    return {
        pass: isAccessible,
        // Display assertion for the report when a test fails
        message: (): string => matcherHint(`${toBeAccessible.name}: ${matcherHintMsg} \n\n ${a11yViolations}`),
    };
}

/**
 * Jest expect matcher to check DOM for accessibility issues with a `@sa11y/preset-rule`
 * @param receivedDom - DOM to be tested for accessibility
 * @param config - A11yConfig to be used to test for accessibility.
 */
export function toBeAccessibleWith(
    receivedDom: Document = document,
    config: A11yConfig
): Promise<jest.CustomMatcherResult> {
    return toBeAccessible(receivedDom, config);
}