vore-rpg/config/jest/peggyTransform.js

'use strict';

const babelJest = require('babel-jest');
const makeCacheKey = require('@jest/create-cache-key-function').default();
const peggy = require("peggy");

const hasJsxRuntime = (() => {
    if (process.env.DISABLE_NEW_JSX_TRANSFORM === 'true') {
        return false;
    }

    try {
        require.resolve('react/jsx-runtime');
        return true;
    } catch (e) {
        return false;
    }
})();

const babelJestInstance = babelJest.createTransformer({
    presets: [
        [
            require.resolve('babel-preset-react-app'),
            {
                runtime: hasJsxRuntime ? 'automatic' : 'classic',
            },
        ],
    ],
    babelrc: false,
    configFile: false,
});

const startRuleFinder = /\s*\/\/\s*peggy-loader:startRule\s*(\S+)\s*\n/g

module.exports = {
    canInstrument: babelJestInstance.canInstrument,
    createTransformer() {
        return this;
    },
    getCacheKey(sourceText, sourcePath, configString, options) {
        return makeCacheKey(sourceText, sourcePath, configString, options) + babelJestInstance.getCacheKey(sourceText, sourcePath, configString, options)
    },
    process(sourceText, sourcePath, configString, options) {
        const start = Array.from({ [Symbol.iterator]() { return sourceText.matchAll(startRuleFinder) } }, ([_, rule]) => rule)
        const resultSource = peggy.generate(sourceText, {
            grammarSource: this.resourcePath,
            allowedStartRules: start,
            output: "source",
            format: "es",
        })
        return babelJest.process(resultSource, sourcePath, configString, options)
    },
}