Fix requirements-txt-fixer for comments at end of file

Author: asottile

pre_commit_hooks/requirements_txt_fixer.py

@@ -63,9 +63,16 @@ def fix_requirements(f):
         else:
             requirement.value = line
 
+    # if a file ends in a comment, preserve it at the end
+    if requirements[-1].value is None:
+        rest = requirements.pop().comments
+    else:
+        rest = []
+
     for requirement in sorted(requirements):
         after.extend(requirement.comments)
         after.append(requirement.value)
+    after.extend(rest)
 
     after_string = b''.join(after)
 

tests/requirements_txt_fixer_test.py

@@ -11,6 +11,8 @@
     (
         (b'', PASS, b''),
         (b'\n', PASS, b'\n'),
+        (b'# intentionally empty\n', PASS, b'# intentionally empty\n'),
+        (b'foo\n# comment at end\n', PASS, b'foo\n# comment at end\n'),
         (b'foo\nbar\n', FAIL, b'bar\nfoo\n'),
         (b'bar\nfoo\n', PASS, b'bar\nfoo\n'),
         (b'#comment1\nfoo\n#comment2\nbar\n', FAIL, b'#comment2\nbar\n#comment1\nfoo\n'),