feat(R): check README.Rmd changes are rendered

Adds the githook generated by usethis::use_readme_rmd() to pre-commits,
ensuring any changes made to README.Rmd are properly synchronised to the
rendered README.md file.

.pre-commit-hooks.yaml

@@ -129,6 +129,15 @@
   minimum_pre_commit_version: 0.15.0
   description: 'Run lintr against R code'
 
+- id: r-readme
+  name: 'Generated README.Rmd'
+  entry: run-r-readme.sh
+  language: 'script'
+  files: README\.Rmd$
+  pass_filenames: false
+  minimum_pre_commit_version: 0.15.0
+  description: 'Check README.md in-sync with README.Rmd'
+
 - id: buf-lint
   name: 'Lint protobuf files'
   entry: buf-lint.sh

README.md

@@ -19,6 +19,7 @@ Hooks:
 * `rust-doc`: runs `cargo doc` against the workspace - great for linting [intra-doc links]
 * `r-stylr`: runs [`stylr`] to format R code
 * `r-lintr`: static analysis of R code with [`lintr`]
+* `r-readme`: ensure README.Rmd changes are rendered to README.md
 * `buf-lint`: runs [`buf`] lints against protobuf files
 * `buf-breaking`: protobuf breaking change detection using [`buf`]
 
@@ -87,6 +88,8 @@ repos:
 
       - id: r-lintr
         stages: [commit, push]
+
+      - id: r-readme
         stages: [commit, push]
 
       - id: buf-lint

run-r-readme.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+README=($(git diff --cached --name-only | grep -Ei '^README\.[R]?md$'))
+
+if [[ ${#README[@]} == 0 ]]; then
+  exit 0
+fi
+
+if [[ README.Rmd -nt README.md ]]; then
+  echo -e "README.md is out of date; please re-knit README.Rmd"
+  exit 1
+elif [[ ${#README[@]} -lt 2 ]]; then
+  echo -e "README.Rmd and README.md should be both staged"
+  exit 1
+fi