npm test
or
npm run testwatch
or
npm test -- watch

Either use the atom babel package, or use gulp and babel to transpile from src to build.

Use of the atom editor is not required. But if you choose to use atom here are some tips.

apm install linter linter-eslint language-babel editorconfig

• Uncheck Lint on fly

• check Disable When NoEslintrc File In Path
• uncheck Use Global Eslint (unchecking seems to be necessary in order to use es2016)

• check Transpile On Save
• src in Babel Source Path
• build in Babel Transpile Path
• put runtime in Optional Transformers