From c72d04e98510f189a0a5f2bb133395d8b07f17f1 Mon Sep 17 00:00:00 2001
From: Amy Qualls <aqualls@gitlab.com>
Date: Sun, 4 Jun 2023 22:28:24 +0000
Subject: [PATCH] Document non-Vale/markdownlint tests, testing pg

The docs-lint markdown job is sneaky, and runs an additional check
that we don't talk much about.
---
 doc/development/documentation/testing.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/doc/development/documentation/testing.md b/doc/development/documentation/testing.md
index 4a7e206da201a..31e495fe9a46c 100644
--- a/doc/development/documentation/testing.md
+++ b/doc/development/documentation/testing.md
@@ -48,6 +48,24 @@ To run tests locally, it's important to:
 
 ### Lint checks
 
+Merge requests containing changes to Markdown (`.md`) files run a `docs-lint markdown`
+job. This job runs `markdownlint`, and a set of tests from
+[`/scripts/lint-doc.sh`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/scripts/lint-doc.sh)
+that look for page content problems that Vale and markdownlint cannot test for.
+The job fails if any of these tests fail:
+
+- Curl (`curl`) commands must use long-form options (`--header`) instead of short options, like `-h`.
+- Documentation pages must contain front matter indicating ownership of the page.
+- Non-standard Unicode space characters (NBSP, NNBSP, ZWSP) must not be used in documentation,
+  because they can cause irregularities in search indexing and grepping.
+- `CHANGELOG.md` must not contain duplicate versions.
+- No files in the `doc/` directory may be executable.
+- Use `index.md` instead of `README.md`.
+- Directories and file names must use underscores instead of dashes.
+- Directories and file names must be in lower case.
+
+#### Run lint checks locally
+
 Lint checks are performed by the [`lint-doc.sh`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/scripts/lint-doc.sh)
 script and can be executed with the help of a Rake task as follows:
 
-- 
GitLab