[doc] Add `trailing-newlines` example (#6839)

Use literalinclude for including python file in examples.

5 files changed, 13 insertions, 8 deletions

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index aee7aa46f..04b7dcc29 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -8,7 +8,12 @@ repos:
       - id: trailing-whitespace
         exclude: tests(/\w*)*/functional/t/trailing_whitespaces.py|tests/pyreverse/data/.*.html|doc/data/messages/t/trailing-whitespace/bad.py
       - id: end-of-file-fixer
-        exclude: tests(/\w*)*/functional/m/missing/missing_final_newline.py|tests/functional/t/trailing_newlines.py
+        exclude: |
+          (?x)^(
+            tests(/\w*)*/functional/m/missing/missing_final_newline.py|
+            tests/functional/t/trailing_newlines.py|
+            doc/data/messages/t/trailing-newlines/bad.py|
+          )$
   - repo: https://github.com/myint/autoflake
     rev: v1.4
     hooks:
diff --git a/doc/data/messages/t/trailing-newlines/bad.py b/doc/data/messages/t/trailing-newlines/bad.py
new file mode 100644
index 000000000..bf21afae0
--- /dev/null
+++ b/doc/data/messages/t/trailing-newlines/bad.py
@@ -0,0 +1,3 @@
+print("apple")
+# The file ends with 2 lines that are empty # +3: [trailing-newlines]
+
diff --git a/doc/data/messages/t/trailing-newlines/details.rst b/doc/data/messages/t/trailing-newlines/details.rst
deleted file mode 100644
index ab8204529..000000000
--- a/doc/data/messages/t/trailing-newlines/details.rst
+++ /dev/null
@@ -1 +0,0 @@
-You can help us make the doc better `by contributing <https://github.com/PyCQA/pylint/issues/5953>`_ !
diff --git a/doc/data/messages/t/trailing-newlines/good.py b/doc/data/messages/t/trailing-newlines/good.py
index c40beb573..57725797f 100644
--- a/doc/data/messages/t/trailing-newlines/good.py
+++ b/doc/data/messages/t/trailing-newlines/good.py
@@ -1 +1 @@
-# This is a placeholder for correct code for this message.
+print("apple")
diff --git a/doc/exts/pylint_messages.py b/doc/exts/pylint_messages.py
index 0e5f13872..3ca0f467a 100644
--- a/doc/exts/pylint_messages.py
+++ b/doc/exts/pylint_messages.py
@@ -105,12 +105,10 @@ def _get_python_code_as_rst(code_path: Path) -> str:
     """
     if not code_path.exists():
         return ""
-    with open(code_path, encoding="utf-8") as f:
-        file_content = f.readlines()
     return f"""\
-.. code-block:: python
-
-{"".join("  " + i for i in file_content)}"""
+.. literalinclude:: /{code_path.relative_to(Path.cwd())}
+   :language: python
+"""
 
 
 def _create_placeholders(