jest.config.js

/**
 * Centralized Jest configuration file for all projects in repo.
 * This file uses Jest `projects` configuration and a couple of undocumented
 * hacks to get around some known issues in Jest configuration and coverage of
 * monorepos.
 */
const path = require('path');

/**
 * `configureProject()` makes a config object for use in the `projects` array.
 *
 * Each config object may use several root-relative paths to files in its
 * package folder. Instead of repetitive strings, like:
 *
 *     {
 *         name: 'peregrine',
 *         displayName: 'Peregrine',
 *         testMatch: '<rootDir>/packages/peregrine/**\/__tests__/*.(test|spec).js'
 *         setupFiles: [
 *             '<rootDir>/packages/peregrine/scripts/shim.js'
 *             '<rootDir>/packages/peregrine/scripts/fetch-mock.js'
 *         ]
 *     }
 *
 * Provide a convenience function via a callback, so the caller can provide
 * a configuration function which receives a path builder.
 *
 *      configureProject('peregrine', 'Peregrine', inPackage => ({
 *          setupFiles: [
 *              inPackage('scripts/shim.js'),
 *              inPackage('scripts/fetch-mock.js')
 *          ],
 *      }))
 *
 */

// Reusable glob string for building `testMatch` patterns.
const testGlob = '/**/__tests__/*.(test|spec).js';

const configureProject = (dir, displayName, cb) =>
    // Defaults that every project config must include.
    // Jest should properly merge some of these in from the root configuration,
    // but it doesn't: https://github.com/facebook/jest/issues/7268
    Object.assign(
        {
            // Set all projects to use the repo root as `rootDir`,
            // to work around https://github.com/facebook/jest/issues/7359
            rootDir: __dirname,
            // Use the dir as a unique "name" property to each config, to force
            // Jest to use different `jest-resolve` instances for each project.
            // This is an undocumented workaround:
            // https://github.com/facebook/jest/issues/6887#issuecomment-417170450
            name: dir,
            // Displays in the CLI.
            displayName,
            // All projects run in the context of the repo root, so each project
            // must specify manually that it only runs tests in its package
            // directory.
            testMatch: [path.join('<rootDir>', 'packages', dir, testGlob)],
            // All project must clear mocks before every test,
            clearMocks: true
        },
        // Pass a function which builds paths inside this project to a callback
        // which returns any additional properties.
        cb(path.join.bind(path, '<rootDir>', 'packages', dir))
    );
const jestConfig = {
    projects: [
        configureProject('peregrine', 'Peregrine', inPackage => ({
            // Expose jsdom to tests.
            browser: true,
            setupFiles: [
                // Shim DOM properties not supported by jsdom
                inPackage('scripts/shim.js'),
                // Always mock `fetch` instead of doing real network calls
                inPackage('scripts/fetch-mock.js')
            ],
            // Set up Enzyme React 16 adapter for testing React components
            setupTestFrameworkScriptFile: path.join(
                '<rootDir>',
                'scripts',
                'jest-enzyme-setup.js'
            ),
            // Give jsdom a real URL for router testing.
            testURL: 'https://localhost/'
        })),
        configureProject('pwa-buildpack', 'Buildpack', () => ({
            testEnvironment: 'node'
        })),
        configureProject('upward-js', 'Upward JS', () => ({
            testEnvironment: 'node'
        })),
        configureProject('venia-concept', 'Venia Concept', inPackage => ({
            // Expose jsdom to tests.
            browser: true,
            moduleNameMapper: {
                // Peregrine imports a virtual module that must be mocked.
                // It would be nice if Venia respected a mock in Peregrine,
                // but it doesn't, so Venia tests will fail without this.
                '^FETCH_ROOT_COMPONENT$': inPackage(
                    '__mocks__/virtualModule.js'
                ),
                // Mock binary files to avoid excess RAM usage.
                '\\.(jpg|jpeg|png)$': inPackage('__mocks__/fileMock.js'),
                // CSS module classes are dynamically generated, but that makes
                // it hard to test React components using DOM classnames.
                // This mapping forces CSS Modules to return literal identies,
                // so e.g. `classes.root` is always `"root"`.
                '\\.css$': 'identity-obj-proxy',
                '\\.svg$': 'identity-obj-proxy',
                // Re-write imports to Peregrine to ensure they're not pulled
                // from the build artifacts on disk in `dist`.
                '^@magento/peregrine(/*(?:.+)*)':
                    '<rootDir>/packages/peregrine/src/$1'
            },
            // Reproduce the Webpack resolution config that lets Venia import
            // from `src` instead of with relative paths:
            modulePaths: [
                inPackage(),
                inPackage('node_modules'),
                '<rootDir>/node_modules'
            ],
            // Set up Enzyme React 16 adapter for testing React components
            setupTestFrameworkScriptFile: path.join(
                '<rootDir>',
                'scripts',
                'jest-enzyme-setup.js'
            ),
            // Give jsdom a real URL for router testing.
            testURL: 'https://localhost/',
            transform: {
                // Reproduce the Webpack `graphql-tag/loader` that lets Venia
                // import `.graphql` files into JS.
                '\\.(gql|graphql)$': 'jest-transform-graphql',
                // Use the default babel-jest for everything else.
                '.*': 'babel-jest'
            },
            // Normally babel-jest ignores node_modules and only transpiles the
            // current package's source. This forces babel-jest to transpile
            // Peregrine as well, when it's testing Venia. That way, Peregrine
            // changes don't require a full compile.
            transformIgnorePatterns: ['node_modules/(?!@magento/peregrine)']
        })),
        // Test any root CI scripts as well, to ensure stable CI behavior.
        configureProject('scripts', 'CI Scripts', () => ({
            testEnvironment: 'node',
            testMatch: [`<rootDir>/scripts/${testGlob}`]
        }))
    ],
    // Include files with zero tests in overall coverage analysis by specifying
    // coverage paths manually.
    collectCoverage: true,
    collectCoverageFrom: [
        // Code directories
        'packages/*/{src,lib}/**/*.js',
        // Not node_modules
        '!**/node_modules/**',
        // Not __tests__, __helpers__, or __any_double_underscore_folders__
        '!**/__[[:alpha:]]*__/**',
        // Not this file itself
        '!jest.config.js'
    ],
    // Don't look for test files in these directories.
    testPathIgnorePatterns: [
        'dist',
        'node_modules',
        '__fixtures__',
        '__helpers__',
        '__snapshots__'
    ]
};

if (process.env.npm_lifecycle_event === 'test:ci') {
    // Extract test filename from full path, for use in JUnit report attributes.
    const testPathRE = /(^\/packages\/[^\/]+\/|\.spec|\/__tests?__)/g;
    const testPathToFilePath = filepath => filepath.replace(testPathRE, '');

    // Add JUnit reporter for use in CI.
    jestConfig.reporters = [
        'default',
        [
            'jest-junit',
            {
                suiteName: 'Jest unit and functional tests',
                output: './test-results/jest/results.xml',
                suiteNameTemplate: ({ displayName, filepath }) =>
                    `${displayName}: ${testPathToFilePath(
                        testPathToFilePath(filepath)
                    )}`,
                classNameTemplate: ({ classname, title }) =>
                    classname !== title ? classname : '',
                titleTemplate: '{title}'
            }
        ]
    ];
}

module.exports = jestConfig;