feat: unified credits and its cost calculations

surfsense_backend/tests/unit/routes/test_image_gen_quota.py

@@ -0,0 +1,138 @@
+"""Unit tests for the image-generation route's billing-resolution helper.
+
+End-to-end "POST /image-generations returns 402" coverage requires the
+integration harness (real DB, real auth) and lives in
+``tests/integration/document_upload/`` alongside the other quota tests.
+This unit test focuses on the new ``_resolve_billing_for_image_gen``
+helper which:
+
+* Returns ``free`` for Auto mode, even when premium configs exist
+  (Auto-mode billing-tier surfacing is a follow-up).
+* Returns ``free`` for user-owned BYOK configs (positive IDs).
+* Returns the global config's ``billing_tier`` for negative IDs.
+* Honours the per-config ``quota_reserve_micros`` override when present.
+"""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+import pytest
+
+pytestmark = pytest.mark.unit
+
+
+@pytest.mark.asyncio
+async def test_resolve_billing_for_auto_mode(monkeypatch):
+    from app.routes import image_generation_routes
+    from app.services.billable_calls import DEFAULT_IMAGE_RESERVE_MICROS
+
+    search_space = SimpleNamespace(image_generation_config_id=None)
+    tier, model, reserve = await image_generation_routes._resolve_billing_for_image_gen(
+        session=None,  # Not consumed on this code path.
+        config_id=0,  # IMAGE_GEN_AUTO_MODE_ID
+        search_space=search_space,
+    )
+    assert tier == "free"
+    assert model == "auto"
+    assert reserve == DEFAULT_IMAGE_RESERVE_MICROS
+
+
+@pytest.mark.asyncio
+async def test_resolve_billing_for_premium_global_config(monkeypatch):
+    from app.config import config
+    from app.routes import image_generation_routes
+
+    monkeypatch.setattr(
+        config,
+        "GLOBAL_IMAGE_GEN_CONFIGS",
+        [
+            {
+                "id": -1,
+                "provider": "OPENAI",
+                "model_name": "gpt-image-1",
+                "billing_tier": "premium",
+                "quota_reserve_micros": 75_000,
+            },
+            {
+                "id": -2,
+                "provider": "OPENROUTER",
+                "model_name": "google/gemini-2.5-flash-image",
+                "billing_tier": "free",
+            },
+        ],
+        raising=False,
+    )
+
+    search_space = SimpleNamespace(image_generation_config_id=None)
+
+    # Premium with override.
+    tier, model, reserve = await image_generation_routes._resolve_billing_for_image_gen(
+        session=None, config_id=-1, search_space=search_space
+    )
+    assert tier == "premium"
+    assert model == "openai/gpt-image-1"
+    assert reserve == 75_000
+
+    # Free, no override → falls back to default.
+    from app.services.billable_calls import DEFAULT_IMAGE_RESERVE_MICROS
+
+    tier, model, reserve = await image_generation_routes._resolve_billing_for_image_gen(
+        session=None, config_id=-2, search_space=search_space
+    )
+    assert tier == "free"
+    # Provider-prefixed model string for OpenRouter.
+    assert "google/gemini-2.5-flash-image" in model
+    assert reserve == DEFAULT_IMAGE_RESERVE_MICROS
+
+
+@pytest.mark.asyncio
+async def test_resolve_billing_for_user_owned_byok_is_free():
+    """User-owned BYOK configs (positive IDs) cost the user nothing on
+    our side — they pay the provider directly. Always free.
+    """
+    from app.routes import image_generation_routes
+    from app.services.billable_calls import DEFAULT_IMAGE_RESERVE_MICROS
+
+    search_space = SimpleNamespace(image_generation_config_id=None)
+    tier, model, reserve = await image_generation_routes._resolve_billing_for_image_gen(
+        session=None, config_id=42, search_space=search_space
+    )
+    assert tier == "free"
+    assert model == "user_byok"
+    assert reserve == DEFAULT_IMAGE_RESERVE_MICROS
+
+
+@pytest.mark.asyncio
+async def test_resolve_billing_falls_back_to_search_space_default(monkeypatch):
+    """When the request omits ``image_generation_config_id``, the helper
+    must consult the search space's default — so a search space pinned
+    to a premium global config still gates new requests by quota.
+    """
+    from app.config import config
+    from app.routes import image_generation_routes
+
+    monkeypatch.setattr(
+        config,
+        "GLOBAL_IMAGE_GEN_CONFIGS",
+        [
+            {
+                "id": -7,
+                "provider": "OPENAI",
+                "model_name": "gpt-image-1",
+                "billing_tier": "premium",
+            }
+        ],
+        raising=False,
+    )
+
+    search_space = SimpleNamespace(image_generation_config_id=-7)
+    (
+        tier,
+        model,
+        _reserve,
+    ) = await image_generation_routes._resolve_billing_for_image_gen(
+        session=None, config_id=None, search_space=search_space
+    )
+    assert tier == "premium"
+    assert model == "openai/gpt-image-1"