Instrument MDX

[frattaro]

For some background, I'm using Docz and running Cypress testing against it. I want to add code coverage -- ideally that would trickle down to my components that are referenced in the mdx. I've found I can't instrument the MDX output.

Digging, I found that the babel transform for the MDX output appears to ignore any babel configuration:

gatsby/packages/gatsby-plugin-mdx/loaders/mdx-loader.js

Line 201 in 7e431fd

const result = babel.transform(rawMDXOutput, {

If I understand the situation (good possibility I'm missing something important) -- can we add a hook to modify that babel transform? (I would add babel-plugin-istanbul)