From 875ddeddd763f550286d142aad37ac266056049d Mon Sep 17 00:00:00 2001
From: Stein Magnus Jodal <stein.magnus@jodal.no>
Date: Sat, 3 Aug 2024 21:46:29 +0200
Subject: [PATCH] Ignore redundant separator characters

Fixes #176
---
 src/biip/gs1/_messages.py  | 19 +++++++------------
 tests/gs1/test_messages.py | 30 ++++++++++++++++--------------
 2 files changed, 23 insertions(+), 26 deletions(-)

diff --git a/src/biip/gs1/_messages.py b/src/biip/gs1/_messages.py
index 1bf97ee7..99243dac 100644
--- a/src/biip/gs1/_messages.py
+++ b/src/biip/gs1/_messages.py
@@ -66,7 +66,8 @@ def parse(
             A message object with one or more element strings.
 
         Raises:
-            ParseError: If a fixed-length field ends with a separator character.
+            ValueError: If the ``separator_char`` isn't exactly 1 character long.
+            ParseError: If the parsing fails.
         """
         value = value.strip()
         element_strings: List[GS1ElementString] = []
@@ -83,17 +84,11 @@ def parse(
 
             rest = rest[len(element_string) :]
 
-            if rest.startswith(tuple(separator_chars)):
-                if element_string.ai.fnc1_required:
-                    rest = rest[1:]
-                else:
-                    separator_char = rest[0]
-                    msg = (
-                        f"Element String {element_string.as_hri()!r} has fixed length "
-                        "and should not end with a separator character. "
-                        f"Separator character {separator_char!r} found in {value!r}."
-                    )
-                    raise ParseError(msg)
+            # Separator characters are accepted inbetween any element string,
+            # even if the AI doesn't require it. See GS1 General Specifications,
+            # section 7.8.6 for details.
+            while rest.startswith(tuple(separator_chars)):
+                rest = rest[1:]
 
         return cls(value=value, element_strings=element_strings)
 
diff --git a/tests/gs1/test_messages.py b/tests/gs1/test_messages.py
index 9ed23a14..00e11cf5 100644
--- a/tests/gs1/test_messages.py
+++ b/tests/gs1/test_messages.py
@@ -150,20 +150,22 @@ def test_parse_fails_if_unparsed_data_left(value: str, error: str) -> None:
     assert str(exc_info.value) == error
 
 
-def test_parse_fails_if_fixed_length_field_ends_with_separator_char() -> None:
-    # 15... is a fixed length date.
-    # \x1d is the default separator character in an illegal position.
-    # 10... is any other field.
-    value = "15210526\x1d100329"
-
-    with pytest.raises(ParseError) as exc_info:
-        GS1Message.parse(value)
-
-    assert str(exc_info.value) == (
-        r"Element String '(15)210526' has fixed length and "
-        r"should not end with a separator character. "
-        r"Separator character '\x1d' found in '15210526\x1d100329'."
-    )
+@pytest.mark.parametrize(
+    ("value", "expected_hri"),
+    [
+        # A separator at the end of the string is never needed.
+        ("15210526100329\x1d", "(15)210526(10)0329"),
+        # 15... is a fixed length date, and should not end with a separator.
+        ("15210526\x1d100329", "(15)210526(10)0329"),
+        # Double separator chars are ignored.
+        (
+            "0107032069804988100329\x1d\x1d15210526",
+            "(01)07032069804988(10)0329(15)210526",
+        ),
+    ],
+)
+def test_parse_ignores_redundant_separator_chars(value: str, expected_hri: str) -> None:
+    assert GS1Message.parse(value).as_hri() == expected_hri
 
 
 def test_parse_strips_surrounding_whitespace() -> None: