feat: record embedding call usage into ModelUsageTracker

backend/tests/observability/test_embedding_usage_tracking.py

@@ -0,0 +1,65 @@
+"""Verifies OpenAICompatibleEmbeddingProvider records usage into ModelUsageTracker."""
+
+from __future__ import annotations
+
+from unittest.mock import MagicMock, patch
+
+import httpx
+import pytest
+
+from app.infrastructure.embedding.openai_compatible_embedding_provider import OpenAICompatibleEmbeddingProvider
+from app.shared.model_usage_tracker import get_model_usage_tracker
+
+
+@pytest.fixture(autouse=True)
+def _reset_tracker():
+    """Clear the process-wide tracker before and after each test in this file."""
+    get_model_usage_tracker()._entries.clear()
+    yield
+    get_model_usage_tracker()._entries.clear()
+
+
+def _fake_response(usage: dict) -> MagicMock:
+    """Build a fake httpx.Response-like object for a successful embeddings call."""
+    resp = MagicMock(spec=httpx.Response)
+    resp.raise_for_status.return_value = None
+    resp.json.return_value = {
+        "data": [{"index": 0, "embedding": [0.1] * 1024}],
+        "usage": usage,
+    }
+    return resp
+
+
+def test_successful_embed_records_usage():
+    """A successful embeddings call must record token usage under 'embedding:<model>'."""
+    provider = OpenAICompatibleEmbeddingProvider()
+    provider.api_key = "test-key"
+    with patch("httpx.post", return_value=_fake_response({"prompt_tokens": 3, "total_tokens": 3})):
+        provider.embed_query("hello")
+
+    entry = get_model_usage_tracker().get("embedding", provider.model)
+    assert entry is not None
+    assert entry.total_tokens == 3
+    assert entry.status == "ok"
+
+
+def test_failed_embed_records_error():
+    """An HTTP error from the embeddings endpoint must be recorded as a failure, then re-raised."""
+    provider = OpenAICompatibleEmbeddingProvider()
+    provider.api_key = "test-key"
+    failing_response = MagicMock(spec=httpx.Response)
+    failing_response.status_code = 500
+    failing_response.text = "boom"
+    failing_response.request = MagicMock()
+    failing_response.request.url = "http://example.com/embeddings"
+    failing_response.raise_for_status.side_effect = httpx.HTTPStatusError(
+        "boom", request=failing_response.request, response=failing_response
+    )
+    with patch("httpx.post", return_value=failing_response):
+        with pytest.raises(httpx.HTTPStatusError):
+            provider.embed_query("hello")
+
+    entry = get_model_usage_tracker().get("embedding", provider.model)
+    assert entry is not None
+    assert entry.status == "error"
+    assert entry.call_count_error == 1