Fix trailing whitespace/newline logic

Author: pwilkin

scripts/jinja/jinja-tester.py

@@ -142,14 +142,16 @@ def format_template_content(template_content):
 
         i += 1
 
-    # Clean up leading and trailing empty lines that would change output
+    # Clean up trailing newlines and spaces
     result = result.rstrip()
 
-    # But preserve the exact trailing newline behavior of the original
-    if template_content.endswith("\n") and not result.endswith("\n"):
-        result += "\n"
-    elif not template_content.endswith("\n") and result.endswith("\n"):
-        result = result[:-1]
+    # Copy the newline / space count from the original
+    tc_rstrip = template_content.rstrip()
+    if not tc_rstrip.endswith("-%}") and not tc_rstrip.endswith(r'-}}'):
+        # If orig ends with -%} or -}}, that means all newlines are stripped anyways
+        # So we shouldn't add anything
+        trailing_length = len(template_content) - len(tc_rstrip)
+        result += template_content[:-trailing_length]
 
     return result