From 7adca0a1f308139ee95ea76dcd9fa73909625bb1 Mon Sep 17 00:00:00 2001
From: David Blaikie <dblaikie@gmail.com>
Date: Thu, 22 Aug 2024 20:06:36 +0000
Subject: [PATCH] Add docs to README.md

---
 testing/file_test/README.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/testing/file_test/README.md b/testing/file_test/README.md
index 8f5f208d922ab..ca9513cde650f 100644
--- a/testing/file_test/README.md
+++ b/testing/file_test/README.md
@@ -123,6 +123,11 @@ Supported comment markers are:
 
         Replaced with `${TEST_TMPDIR}/temp_file`.
 
+    -   `%{identifier}`
+
+        Replaces some implementation-specific identifier with a value. (Mappings
+        provided by way of an optional `MyFileTest::GetArgReplacements`)
+
     ARGS can be specified at most once. If not provided, the FileTestBase child
     is responsible for providing default arguments.