From 9d4d7ef806c17387af9778725cd65a5e7ed10e39 Mon Sep 17 00:00:00 2001
From: historia <historiavg@proton.me>
Date: Wed, 19 Aug 2026 04:45:28 -0400
Subject: fix: limit chunk size to 250

---
 tests/test_audio.py | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

(limited to 'tests/test_audio.py')

diff --git a/tests/test_audio.py b/tests/test_audio.py
index fb448f8..c043766 100644
--- a/tests/test_audio.py
+++ b/tests/test_audio.py
@@ -1,9 +1,11 @@
 """Tests for audio helpers: speed parameters, chunk cleanup, encoding,
-command construction, and duration verification."""
+command construction, duration verification, and audio concatenation."""
 
 import tempfile
 import unittest
+import wave
 from pathlib import Path
+from unittest.mock import patch
 
 from converter import audio
 from converter import config
@@ -17,6 +19,7 @@ from converter.audio import (
     build_ffmetadata,
     build_m4b_chapters_command,
     cleanup_chunks,
+    concat_audio_files,
     speed_export_params,
     verify_output_duration,
 )
@@ -422,5 +425,67 @@ class BuildM4bChaptersCommandMetaTests(unittest.TestCase):
         self.assertNotIn("-metadata", cmd)
 
 
+class ConcatAudioFilesTests(unittest.TestCase):
+    """Concatenation of sub-request audio into one chunk file."""
+
+    @staticmethod
+    def _write_wav(path: Path, frames: bytes, framerate: int = 24000) -> Path:
+        with wave.open(str(path), "wb") as wav_file:
+            wav_file.setnchannels(1)
+            wav_file.setsampwidth(2)
+            wav_file.setframerate(framerate)
+            wav_file.writeframes(frames)
+        return path
+
+    def test_wav_files_are_merged_in_order(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            first = self._write_wav(Path(tmp) / "a.wav", b"\x01\x00" * 10)
+            second = self._write_wav(Path(tmp) / "b.wav", b"\x02\x00" * 20)
+            destination = Path(tmp) / "out.wav"
+            concat_audio_files([first, second], destination)
+            with wave.open(str(destination), "rb") as wav_file:
+                self.assertEqual(wav_file.getframerate(), 24000)
+                self.assertEqual(wav_file.getnchannels(), 1)
+                self.assertEqual(wav_file.getsampwidth(), 2)
+                frames = wav_file.readframes(wav_file.getnframes())
+            self.assertEqual(frames, b"\x01\x00" * 10 + b"\x02\x00" * 20)
+
+    def test_single_wav_file_is_copied(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            source = self._write_wav(Path(tmp) / "a.wav", b"\x03\x00" * 15)
+            destination = Path(tmp) / "out.wav"
+            concat_audio_files([source], destination)
+            with wave.open(str(destination), "rb") as wav_file:
+                self.assertEqual(wav_file.readframes(wav_file.getnframes()),
+                                 b"\x03\x00" * 15)
+
+    def test_empty_source_list_raises(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            with self.assertRaises(ValueError):
+                concat_audio_files([], Path(tmp) / "out.wav")
+
+    def test_mismatched_wav_parameters_fall_back_to_ffmpeg(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            first = self._write_wav(Path(tmp) / "a.wav", b"\x01\x00" * 10, framerate=24000)
+            second = self._write_wav(Path(tmp) / "b.wav", b"\x02\x00" * 10, framerate=16000)
+            destination = Path(tmp) / "out.wav"
+            with patch("converter.audio.shutil.which", return_value=None), \
+                    self.assertRaises(RuntimeError) as ctx:
+                concat_audio_files([first, second], destination)
+            self.assertIn("ffmpeg", str(ctx.exception))
+            # The wave-module path must not have written a partial output.
+            self.assertFalse(destination.exists())
+
+    def test_non_wav_input_falls_back_to_ffmpeg(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            source = Path(tmp) / "part.mp3"
+            source.write_bytes(b"not a wav file")
+            destination = Path(tmp) / "out.wav"
+            with patch("converter.audio.shutil.which", return_value=None), \
+                    self.assertRaises(RuntimeError) as ctx:
+                concat_audio_files([source], destination)
+            self.assertIn("ffmpeg", str(ctx.exception))
+
+
 if __name__ == "__main__":
     unittest.main()
-- 
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