Improve handling of transpiled packages in unit tests (#14432)

package.json

@@ -186,7 +186,7 @@
 		"test-e2e": "wp-scripts test-e2e --config packages/e2e-tests/jest.config.js",
 		"test-e2e:watch": "npm run test-e2e -- --watch",
 		"test-php": "npm run lint-php && npm run test-unit-php",
-		"test-unit": "wp-scripts test-unit-js --config test/unit/jest.config.json",
+		"test-unit": "wp-scripts test-unit-js --config test/unit/jest.config.js",
 		"test-unit:update": "npm run test-unit -- --updateSnapshot",
 		"test-unit:watch": "npm run test-unit -- --watch",
 		"test-unit-php": "docker-compose run --rm wordpress_phpunit phpunit",

packages/block-serialization-default-parser/test/index.js

@@ -12,7 +12,7 @@ import { jsTester, phpTester } from '@wordpress/block-serialization-spec-parser/
 /**
  * Internal dependencies
  */
-import { parse } from '../';
+import { parse } from '../src';
 
 describe( 'block-serialization-default-parser-js', jsTester( parse ) );
 

packages/components/src/disabled/test/index.js

@@ -14,7 +14,7 @@ import { Component } from '@wordpress/element';
 import Disabled from '../';
 
 jest.mock( '@wordpress/dom', () => {
-	const focus = require.requireActual( '@wordpress/dom' ).focus;
+	const focus = require.requireActual( '../../../../dom/src' ).focus;
 
 	return {
 		focus: {

test/unit/jest.config.js

@@ -0,0 +1,30 @@
+/**
+ * External dependencies
+ */
+const glob = require( 'glob' ).sync;
+
+// Finds all packages which are transpiled with Babel to force Jest to use their source code.
+const transpiledPackageNames = glob( 'packages/*/src/index.js' )
+	.map( ( fileName ) => fileName.split( '/' )[ 1 ] );
+
+module.exports = {
+	rootDir: '../../',
+	moduleNameMapper: {
+		[ `@wordpress\\/(${ transpiledPackageNames.join( '|' ) })$` ]: 'packages/$1/src',
+	},
+	preset: '@wordpress/jest-preset-default',
+	setupFiles: [
+		'core-js/fn/symbol/async-iterator',
+		'<rootDir>/test/unit/config/gutenberg-phase.js',
+	],
+	testURL: 'http://localhost',
+	testPathIgnorePatterns: [
+		'/node_modules/',
+		'/packages/e2e-tests',
+		'<rootDir>/.*/build/',
+		'<rootDir>/.*/build-module/',
+	],
+	transformIgnorePatterns: [
+		'node_modules/(?!(simple-html-tokenizer)/)',
+	],
+};