extract resolve_fallback_voice_spec to domain/voice_resolution.py; fix missing get_default_voice import and __custom_mix reset bug

tests/test_voice_fallback.py

@@ -0,0 +1,139 @@
+import sys
+import types
+
+if "soundfile" not in sys.modules:
+    soundfile_stub = types.ModuleType("soundfile")
+
+    class _SoundFileStub:  # pragma: no cover - placeholder to satisfy imports
+        def __init__(self, *args: object, **kwargs: object) -> None:
+            raise RuntimeError("soundfile is not installed in the test environment")
+
+    soundfile_stub.SoundFile = _SoundFileStub  # type: ignore[attr-defined]
+    sys.modules["soundfile"] = soundfile_stub
+
+if "static_ffmpeg" not in sys.modules:
+    sys.modules["static_ffmpeg"] = types.ModuleType("static_ffmpeg")
+
+if "ebooklib" not in sys.modules:
+    ebooklib_stub = types.ModuleType("ebooklib")
+    ebooklib_epub_stub = types.ModuleType("ebooklib.epub")
+    ebooklib_stub.epub = ebooklib_epub_stub  # type: ignore[attr-defined]
+    sys.modules["ebooklib"] = ebooklib_stub
+    sys.modules["ebooklib.epub"] = ebooklib_epub_stub
+
+if "fitz" not in sys.modules:
+    sys.modules["fitz"] = types.ModuleType("fitz")
+
+if "markdown" not in sys.modules:
+    markdown_stub = types.ModuleType("markdown")
+
+    class _MarkdownStub:
+        def __init__(self, *args: object, **kwargs: object) -> None:
+            self.toc_tokens = []
+
+        def convert(self, text: str) -> str:
+            return text
+
+    markdown_stub.Markdown = _MarkdownStub  # type: ignore[attr-defined]
+    sys.modules["markdown"] = markdown_stub
+
+if "bs4" not in sys.modules:
+    bs4_stub = types.ModuleType("bs4")
+
+    class _BeautifulSoupStub:
+        def __init__(self, *args: object, **kwargs: object) -> None:
+            self._text = ""
+
+        def find(self, *args: object, **kwargs: object) -> None:
+            return None
+
+        def get_text(self) -> str:
+            return self._text
+
+        def decompose(self) -> None:  # pragma: no cover - compatibility shim
+            return None
+
+    class _NavigableStringStub(str):
+        pass
+
+    bs4_stub.BeautifulSoup = _BeautifulSoupStub  # type: ignore[attr-defined]
+    bs4_stub.NavigableString = _NavigableStringStub  # type: ignore[attr-defined]
+    sys.modules["bs4"] = bs4_stub
+
+
+from unittest.mock import patch, MagicMock
+
+
+class TestResolveFallbackVoiceSpec:
+    """Tests for the voice fallback resolution helper."""
+
+    def test_uses_base_voice_spec(self) -> None:
+        from abogen.domain.voice_resolution import resolve_fallback_voice_spec
+
+        result = resolve_fallback_voice_spec(
+            base_spec="af_heart",
+            job_voice="af_bella",
+            voice_cache_keys=[],
+        )
+        assert result == "af_heart"
+
+    def test_falls_back_to_job_voice(self) -> None:
+        from abogen.domain.voice_resolution import resolve_fallback_voice_spec
+
+        result = resolve_fallback_voice_spec(
+            base_spec="",
+            job_voice="af_bella",
+            voice_cache_keys=[],
+        )
+        assert result == "af_bella"
+
+    def test_skips_custom_mix_uses_job_voice(self) -> None:
+        from abogen.domain.voice_resolution import resolve_fallback_voice_spec
+
+        result = resolve_fallback_voice_spec(
+            base_spec="__custom_mix",
+            job_voice="af_bella",
+            voice_cache_keys=[],
+        )
+        assert result == "af_bella"
+
+    def test_falls_back_to_voice_cache(self) -> None:
+        from abogen.domain.voice_resolution import resolve_fallback_voice_spec
+
+        result = resolve_fallback_voice_spec(
+            base_spec="",
+            job_voice="",
+            voice_cache_keys=["kokoro:af_heart"],
+        )
+        assert result == "af_heart"
+
+    def test_skips_custom_mix_in_cache(self) -> None:
+        from abogen.domain.voice_resolution import resolve_fallback_voice_spec
+
+        result = resolve_fallback_voice_spec(
+            base_spec="",
+            job_voice="",
+            voice_cache_keys=["__custom_mix", "kokoro:af_heart"],
+        )
+        assert result == "af_heart"
+
+    def test_falls_back_to_default_voice(self) -> None:
+        from abogen.domain.voice_resolution import resolve_fallback_voice_spec
+
+        with patch("abogen.domain.voice_resolution.get_default_voice", return_value="af_heart"):
+            result = resolve_fallback_voice_spec(
+                base_spec="",
+                job_voice="",
+                voice_cache_keys=[],
+            )
+        assert result == "af_heart"
+
+    def test_empty_base_and_job_with_cache(self) -> None:
+        from abogen.domain.voice_resolution import resolve_fallback_voice_spec
+
+        result = resolve_fallback_voice_spec(
+            base_spec="",
+            job_voice="",
+            voice_cache_keys=["kokoro:af_bella", "kokoro:af_heart"],
+        )
+        assert result == "af_bella"