fix: quote newlines to distinguish from escaped newline strings

Resolves #49

Author: spaceone

src/logfmter/formatter.py

@@ -60,7 +60,12 @@ def format_string(cls, value: str) -> str:
         """
         needs_dquote_escaping = '"' in value
         needs_newline_escaping = "\n" in value
-        needs_quoting = " " in value or "=" in value or needs_dquote_escaping
+        needs_quoting = (
+            " " in value
+            or "=" in value
+            or needs_dquote_escaping
+            or needs_newline_escaping
+        )
         needs_backslash_escaping = "\\" in value and needs_quoting
 
         if needs_backslash_escaping:

tests/test_formatter.py

@@ -22,8 +22,8 @@
     # If the string is empty, then it should be left empty.
     ("", ""),
     # If the string contains a newline, then it should be escaped.
-    ("\n", "\\n"),
-    ("\n\n", "\\n\\n"),
+    ("\n", '"\\n"'),
+    ("\n\n", '"\\n\\n"'),
     # If the string contains a backslash and needs to be quoted, then
     # the backslashes need to be escaped.
     ("\\", "\\"),