docs: add diff_test note to generated_file_test
fixes #3184
diff --git a/docs/Built-ins.md b/docs/Built-ins.md
index 7acc6c6..4a2e35f 100755
--- a/docs/Built-ins.md
+++ b/docs/Built-ins.md
@@ -1953,6 +1953,10 @@
This is useful for testing, where a "snapshot" or "golden" file is checked in,
so that you can code review changes to the generated output.
+Note, for binary files you can just use the `diff_test` rule from bazel-skylib.
+See https://github.com/bazelbuild/bazel-skylib/blob/main/docs/diff_test_doc.md
+and https://blog.aspect.dev/bazel-can-write-to-the-source-folder
+
**PARAMETERS**
diff --git a/internal/generated_file_test/generated_file_test.bzl b/internal/generated_file_test/generated_file_test.bzl
index 4f33a7f..39565be 100644
--- a/internal/generated_file_test/generated_file_test.bzl
+++ b/internal/generated_file_test/generated_file_test.bzl
@@ -8,6 +8,10 @@
This is useful for testing, where a "snapshot" or "golden" file is checked in,
so that you can code review changes to the generated output.
+ Note, for binary files you can just use the `diff_test` rule from bazel-skylib.
+ See https://github.com/bazelbuild/bazel-skylib/blob/main/docs/diff_test_doc.md
+ and https://blog.aspect.dev/bazel-can-write-to-the-source-folder
+
Args:
name: Name of the rule.
generated: a Label of the output file generated by another rule
