From 8a84699ee052b094f403c7470134af0c768becb3 Mon Sep 17 00:00:00 2001
From: Scott Boudreaux <scott@elyanlabs.com>
Date: Wed, 20 May 2026 15:56:50 -0500
Subject: [PATCH] TEST: build the ZIP fixture little-endian in the local-header
 test
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test_load_zip_with_local_header_extra_field hand-builds a ZIP and wrote
the positions/offsets arrays with `.tobytes()`, which serializes in
native byte order. The TRX format stores arrays little-endian on disk
(see `_get_dtype_little_endian` / `_ensure_little_endian`), and the
reader decodes them little-endian — so on a big-endian host (s390x) the
fixture wrote big-endian bytes that the reader then byte-swapped, and the
test failed with mismatched values.

Serialize the fixture arrays explicitly as little-endian
(`astype("<f4")` / `astype("<u8")`) so the test is valid regardless of
host endianness. Library code is unchanged.

Fixes #113

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 trx/tests/test_memmap.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/trx/tests/test_memmap.py b/trx/tests/test_memmap.py
index 21451a4..1436a1b 100644
--- a/trx/tests/test_memmap.py
+++ b/trx/tests/test_memmap.py
@@ -523,10 +523,12 @@ def test_load_zip_with_local_header_extra_field():
             local_info = []
             extra = b"\x00\x00\x04\x00TEST"  # 8-byte extra field
 
+            # TRX stores arrays little-endian on disk; serialize the fixture
+            # explicitly so it is valid on big-endian hosts too (issue #113).
             for name, data in [
                 ("header.json", json.dumps(header).encode()),
-                ("positions.3.float32", positions.tobytes()),
-                ("offsets.uint64", offsets.tobytes()),
+                ("positions.3.float32", positions.astype("<f4").tobytes()),
+                ("offsets.uint64", offsets.astype("<u8").tobytes()),
             ]:
                 offset = f.tell()
                 fname = name.encode()