I've been wanting to upgrade my version of Hugo, but the Casper 2 theme I was using didn't support it. As a first step to this transition is to use Casper 3. It looks similar to my old theme, is easy to set up, but seems to be missing some features.

I cloned the repository, and changed the theme in my config.toml to theme = "hugo-casper3". The article images weren't showing because the Casper 3 theme uses feature_image instead of image and requires a leading slash in the path (which was optional in 2). I fixed both of these on my mmark articles using:

find . -name '*.mmark' -exec sed -i -E 's|^image( ?[=:] ?)"/?images|feature_image\1"/images|' {} \;

# Testing features

To make sure the conversion went well I created a list of articles using different features:

Article Image Code File List Quote Table LaTeX RMarkdown
Extracting Skills with Conjugations
JobPosting Schema
Real Roots of Polynomials
Blogdown

The result of my tests:

• Images, files and links are working
• Syntax highlighting now works
• Quotes work as before, lists look better (the CSS was broken before)
• LaTeX was broken
• RMarkdown files lost their images

I've also lost a lot of features from the list page such as pagination, contact details and a cover image. The theme doesn't look well supported, and I will investigate other themes in the future. But this is a start and I can work on remediating LaTeX and RMarkdown.