From 533b8a645e9768347e869fb5ace9b689bbcf9c30 Mon Sep 17 00:00:00 2001
From: Dom Dwyer <dom@itsallbroken.com>
Date: Thu, 25 Aug 2022 00:00:09 +0200
Subject: [PATCH] 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 |  9 +++++++++
 README.md              |  3 +++
 run-r-readme.sh        | 17 +++++++++++++++++
 3 files changed, 29 insertions(+)
 create mode 100755 run-r-readme.sh

diff --git a/.pre-commit-hooks.yaml b/.pre-commit-hooks.yaml
index b63779f..e7683c0 100644
--- a/.pre-commit-hooks.yaml
+++ b/.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
diff --git a/README.md b/README.md
index 521f4b0..7e68181 100644
--- a/README.md
+++ b/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
diff --git a/run-r-readme.sh b/run-r-readme.sh
new file mode 100755
index 0000000..f9d3ff0
--- /dev/null
+++ b/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+  echo -e "README.md is out of date; please re-knit README.Rmd"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
\ No newline at end of file