- iframe rendered
  - test libs loaded with script tags in <head>
  - mocha element

run tests
- set the `onload` prop of the iframe to run tests function
- programmatically reload the iframe to re-run the tests
- remove elements in iframe body with loop (could be an issue, but there are only 3 elements)
- create a new mocha div element
-  append div#mocha to body
- create script elements for
  - user's code
  - spec code
  - script to get test results
- append scripts to iframe body
