.babelrc

{
    "presets": [
        ["@babel/preset-env", {
            "useBuiltIns": "entry",
            "corejs": "3"
        }]
    ],
    "env": {
        "test": {
            "plugins": ["istanbul",
                ["@babel/plugin-proposal-decorators", {
                    "legacy": true
                }],
                "@babel/plugin-proposal-function-sent",
                "@babel/plugin-proposal-export-namespace-from",
                "@babel/plugin-proposal-numeric-separator",
                "@babel/plugin-proposal-throw-expressions",
                ["@babel/plugin-proposal-class-properties", {
                    "loose": true
                }],
                ["@babel/plugin-transform-runtime",
                    {
                        "regenerator": true
                    }
                ]
            ]
        }
    },
    "retainLines": true,
    "sourceMaps": true
}