getTest(webpackConfig) {
        const extensions = [
            'm?jsx?', // match .js and .jsx and .mjs
        ];

        if (webpackConfig.useBabelTypeScriptPreset) {
            extensions.push('tsx?'); // match .ts and .tsx
        }

        return new RegExp(`\\.(${extensions.join('|')})$`);
    }
@param {WebpackConfig} webpackConfig
@returns {RegExp} to use for eslint-loader `test` rule