Make _comment() preserve trailing newlines.

2 files changed, 10 insertions, 2 deletions

diff --git a/kconfiglib.py b/kconfiglib.py
index c6d2a07..fa98855 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -3644,10 +3644,13 @@ def _sep_lines(*args):
     return "\n".join(args)
 
 def _comment(s):
-    """Returns a new string with "# " inserted before each line in 's'."""
+    """Returns a new string with "#" inserted before each line in 's'."""
     if not s:
         return "#"
-    return "\n".join(["#" + line for line in s.splitlines()])
+    res = "".join(["#" + line for line in s.splitlines(True)])
+    if s.endswith("\n"):
+        return res + "#"
+    return res
 
 def _get_lines(filename):
     """Returns a list of lines from 'filename', joining any line ending in \\
diff --git a/testsuite.py b/testsuite.py
index dd69ffe..f9378f9 100644
--- a/testsuite.py
+++ b/testsuite.py
@@ -996,8 +996,13 @@ def run_selftests():
            format(read_header))
 
     write_and_verify_header("")
+    write_and_verify_header(" ")
+    write_and_verify_header("\n")
+    write_and_verify_header("\n\n")
     write_and_verify_header("#")
     write_and_verify_header("a")
+    write_and_verify_header("a\n")
+    write_and_verify_header("a\n\n")
     write_and_verify_header("abcdef")
     write_and_verify_header("foo\nbar baz\n\n\n qaz#")