test: P3-1 第二十二波 TTS音频合并+流式服务单元测试 14个

- AudioMerger 7个（空列表/单文件/多文件/wav格式/异常/临时目录清理）
- TTSStreamingService 7个（空文本/过长文本/短文本成功/合成失败/无audio_url/分块推送/send_json容错）
- 合计 14 个测试全部通过

tests/unit/test_tts_audio_merger.py

@@ -0,0 +1,296 @@
+"""
+TTS 相关单元测试（第二十二波）
+
+覆盖：
+- AudioMerger (空列表/单文件/多文件合并/格式/异常)
+"""
+
+import os
+import subprocess
+import tempfile
+
+import pytest
+
+from packages.application.tts_job.audio_merger import (
+    AudioMergeError,
+    AudioMerger,
+)
+
+
+def _make_silence(duration: float = 0.5, sample_rate: int = 22050, fmt: str = "mp3") -> str:
+    """生成一段静音音频文件，返回路径。"""
+    tmp = tempfile.NamedTemporaryFile(suffix=f".{fmt}", delete=False)
+    tmp.close()
+    cmd = [
+        "ffmpeg", "-y", "-f", "lavfi",
+        "-i", f"anullsrc=r={sample_rate}:cl=mono",
+        "-t", str(duration),
+        "-q:a", "9",
+        tmp.name,
+    ]
+    subprocess.run(cmd, capture_output=True, check=True)
+    return tmp.name
+
+
+class TestAudioMerger:
+    """AudioMerger 音频合并器"""
+
+    def test_empty_list_raises(self):
+        """空列表抛错"""
+        merger = AudioMerger()
+        with pytest.raises(AudioMergeError, match="没有可合并"):
+            merger.merge([])
+
+    def test_single_file_returns_content(self):
+        """单个文件直接返回内容"""
+        path = _make_silence(duration=0.3)
+        try:
+            merger = AudioMerger()
+            result = merger.merge([path])
+            assert isinstance(result, bytes)
+            assert len(result) > 100  # 应该有有效数据
+            # 应该和文件本身一致
+            with open(path, "rb") as f:
+                original = f.read()
+            assert result == original
+        finally:
+            os.unlink(path)
+
+    def test_two_files_merged(self):
+        """两个文件合并"""
+        p1 = _make_silence(duration=0.3)
+        p2 = _make_silence(duration=0.4)
+        try:
+            merger = AudioMerger()
+            result = merger.merge([p1, p2])
+            assert isinstance(result, bytes)
+            assert len(result) > 200  # 合并后应该有数据
+            # 写出来用 ffprobe 验证时长
+            tmp = tempfile.NamedTemporaryFile(suffix=".mp3", delete=False)
+            tmp.write(result)
+            tmp.close()
+            try:
+                probe = subprocess.run(
+                    ["ffprobe", "-v", "error", "-show_entries", "format=duration",
+                     "-of", "default=noprint_wrappers=1:nokey=1", tmp.name],
+                    capture_output=True, text=True, check=True,
+                )
+                duration = float(probe.stdout.strip())
+                # 0.3 + 0.4 = 0.7 秒左右，允许一定误差
+                assert 0.5 < duration < 1.0
+            finally:
+                os.unlink(tmp.name)
+        finally:
+            os.unlink(p1)
+            os.unlink(p2)
+
+    def test_three_files_merged(self):
+        """三个文件合并"""
+        paths = [_make_silence(duration=0.2) for _ in range(3)]
+        try:
+            merger = AudioMerger()
+            result = merger.merge(paths)
+            assert isinstance(result, bytes)
+            assert len(result) > 200
+        finally:
+            for p in paths:
+                os.unlink(p)
+
+    def test_wav_format(self):
+        """wav 格式合并"""
+        p1 = _make_silence(duration=0.2, fmt="wav")
+        p2 = _make_silence(duration=0.2, fmt="wav")
+        try:
+            merger = AudioMerger()
+            result = merger.merge([p1, p2], output_format="wav")
+            assert isinstance(result, bytes)
+            # WAV 头部以 RIFF 开头
+            assert result[:4] == b"RIFF"
+        finally:
+            os.unlink(p1)
+            os.unlink(p2)
+
+    def test_nonexistent_file_raises(self):
+        """不存在的文件会抛错"""
+        merger = AudioMerger()
+        with pytest.raises(AudioMergeError):
+            merger.merge(["/nonexistent/path/a.mp3", "/nonexistent/path/b.mp3"])
+
+    def test_cleanup_temp_dir(self):
+        """临时目录会被清理"""
+        p1 = _make_silence(duration=0.2)
+        p2 = _make_silence(duration=0.2)
+        try:
+            import tempfile as _tf
+            before = set(os.listdir(_tf.gettempdir()))
+            merger = AudioMerger()
+            merger.merge([p1, p2])
+            after = set(os.listdir(_tf.gettempdir()))
+            # 不应该残留 tts_merge_ 前缀的目录
+            new_items = after - before
+            tts_items = [i for i in new_items if i.startswith("tts_merge_")]
+            assert len(tts_items) == 0, f"残留临时目录: {tts_items}"
+        finally:
+            os.unlink(p1)
+            os.unlink(p2)
+
+
+# ============================================================
+# TTSStreamingService - 入口路由与边界
+# ============================================================
+
+
+class TestTTSStreamingServiceRouting:
+    """TTSStreamingService 入口路由与边界条件"""
+
+    @pytest.mark.asyncio
+    async def test_empty_text_returns_error(self):
+        """空文本返回错误"""
+        from unittest.mock import AsyncMock, MagicMock
+
+        from packages.application.tts_job.streaming_service import TTSStreamingService
+
+        mock_cosy = MagicMock()
+        svc = TTSStreamingService(cosyvoice_service=mock_cosy)
+        ws = AsyncMock()
+
+        await svc.synthesize_and_stream(ws, {"text": ""})
+
+        ws.send_json.assert_called_once()
+        call_args = ws.send_json.call_args[0][0]
+        assert call_args["type"] == "error"
+        assert "不能为空" in call_args["message"]
+        # 不应该调用 cosyvoice
+        mock_cosy.submit_synthesize_task.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_text_too_long_returns_error(self):
+        """文本过长返回错误"""
+        from unittest.mock import AsyncMock, MagicMock
+
+        from packages.application.tts_job.streaming_service import (
+            _MAX_TEXT_LENGTH,
+            TTSStreamingService,
+        )
+
+        mock_cosy = MagicMock()
+        svc = TTSStreamingService(cosyvoice_service=mock_cosy)
+        ws = AsyncMock()
+
+        long_text = "a" * (_MAX_TEXT_LENGTH + 1)
+        await svc.synthesize_and_stream(ws, {"text": long_text})
+
+        ws.send_json.assert_called_once()
+        call_args = ws.send_json.call_args[0][0]
+        assert call_args["type"] == "error"
+        assert "过长" in call_args["message"]
+        mock_cosy.submit_synthesize_task.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_short_text_routes_to_short_path(self):
+        """短文本走短文本路径（单段合成）"""
+        from unittest.mock import AsyncMock, MagicMock, patch
+
+        from packages.application.tts_job.streaming_service import TTSStreamingService
+
+        mock_cosy = MagicMock()
+        mock_cosy.submit_synthesize_task.return_value = {
+            "audio_url": "https://example.com/audio.mp3",
+            "duration": 3.5,
+        }
+        svc = TTSStreamingService(cosyvoice_service=mock_cosy)
+        ws = AsyncMock()
+
+        # mock 掉音频下载
+        fake_audio = b"fake_audio_data" * 100
+        with patch.object(svc, "_download_audio", return_value=fake_audio):
+            await svc.synthesize_and_stream(ws, {"text": "你好世界", "voice_id": "v1"})
+
+        # 应该调用了 cosy
+        mock_cosy.submit_synthesize_task.assert_called_once()
+        # 应该有 started 和 done 消息
+        msg_types = [c[0][0]["type"] for c in ws.send_json.call_args_list]
+        assert "started" in msg_types
+        assert "done" in msg_types
+        # 应该有音频分块发送
+        assert ws.send_bytes.call_count > 0
+
+    @pytest.mark.asyncio
+    async def test_short_text_cosy_error(self):
+        """短文本合成失败返回错误"""
+        from unittest.mock import AsyncMock, MagicMock
+
+        from packages.application.cosyvoice_service import CosyVoiceError
+        from packages.application.tts_job.streaming_service import TTSStreamingService
+
+        mock_cosy = MagicMock()
+        mock_cosy.submit_synthesize_task.side_effect = CosyVoiceError("音色不存在")
+        svc = TTSStreamingService(cosyvoice_service=mock_cosy)
+        ws = AsyncMock()
+
+        await svc.synthesize_and_stream(ws, {"text": "你好", "voice_id": "v-bad"})
+
+        # 最后一条消息应该是 error
+        last_msg = ws.send_json.call_args_list[-1][0][0]
+        assert last_msg["type"] == "error"
+        assert "音色不存在" in last_msg["message"]
+
+    @pytest.mark.asyncio
+    async def test_short_text_no_audio_url(self):
+        """合成结果没有 audio_url 返回错误"""
+        from unittest.mock import AsyncMock, MagicMock
+
+        from packages.application.tts_job.streaming_service import TTSStreamingService
+
+        mock_cosy = MagicMock()
+        mock_cosy.submit_synthesize_task.return_value = {"duration": 1.0}  # 没有 audio_url
+        svc = TTSStreamingService(cosyvoice_service=mock_cosy)
+        ws = AsyncMock()
+
+        await svc.synthesize_and_stream(ws, {"text": "你好"})
+
+        last_msg = ws.send_json.call_args_list[-1][0][0]
+        assert last_msg["type"] == "error"
+        assert "音频 URL" in last_msg["message"]
+
+    @pytest.mark.asyncio
+    async def test_stream_audio_chunks_returns_total(self):
+        """_stream_audio_chunks 返回正确字节数，分块正确"""
+        from unittest.mock import AsyncMock, MagicMock
+
+        from packages.application.tts_job.streaming_service import (
+            _AUDIO_CHUNK_SIZE,
+            TTSStreamingService,
+        )
+
+        mock_cosy = MagicMock()
+        svc = TTSStreamingService(cosyvoice_service=mock_cosy)
+        ws = AsyncMock()
+
+        # 生成 10000 字节的假音频
+        audio_data = b"x" * 10000
+        total = await svc._stream_audio_chunks(ws, audio_data)
+
+        assert total == 10000
+        # 应该分 ceil(10000/4096) = 3 块
+        expected_chunks = (10000 + _AUDIO_CHUNK_SIZE - 1) // _AUDIO_CHUNK_SIZE
+        assert ws.send_bytes.call_count == expected_chunks
+        # 验证所有块拼接起来等于原数据
+        all_bytes = b"".join(c[0][0] for c in ws.send_bytes.call_args_list)
+        assert all_bytes == audio_data
+
+    @pytest.mark.asyncio
+    async def test_send_json_handles_error(self):
+        """_send_json 发送失败不抛出异常"""
+        from unittest.mock import AsyncMock, MagicMock
+
+        from packages.application.tts_job.streaming_service import TTSStreamingService
+
+        mock_cosy = MagicMock()
+        svc = TTSStreamingService(cosyvoice_service=mock_cosy)
+        ws = AsyncMock()
+        ws.send_json.side_effect = Exception("连接已断开")
+
+        # 不应该抛异常
+        await svc._send_json(ws, {"type": "done"})
+        ws.send_json.assert_called_once()