litellm/tests/test_litellm/test_router_model_cost_isolation.py
Kris Xia d1d2400862
fix(router): register model info under responses/-stripped variant (#27531)
Squash-merged by litellm-agent from krisxia0506's PR.
2026-05-09 20:30:18 +00:00

325 lines
11 KiB
Python

"""
Test that per-deployment custom pricing does not pollute the shared backend
model key in litellm.model_cost.
When two deployments share the same backend model (e.g. vertex_ai/gemini-2.5-flash)
and one has explicit zero-cost pricing in model_info, the other deployment
should still use the built-in pricing.
"""
import os
import sys
import pytest
sys.path.insert(
0, os.path.abspath("../../..")
) # Adds the parent directory to the system path
import litellm
from litellm import Router
from litellm.types.router import Deployment, LiteLLM_Params, ModelInfo
def test_should_not_pollute_shared_key_with_zero_cost_pricing():
"""
When deployment A has input_cost_per_token=0 and deployment B has no
custom pricing, deployment B should still report the built-in pricing
(not zero).
"""
backend_model = "vertex_ai/gemini-2.5-flash"
# Grab built-in pricing before creating any router
builtin_info = litellm.get_model_info(model=backend_model)
builtin_input_cost = builtin_info["input_cost_per_token"]
builtin_output_cost = builtin_info["output_cost_per_token"]
# Sanity: built-in pricing should be non-zero for this model
assert (
builtin_input_cost > 0
), "Test requires a model with non-zero built-in pricing"
assert (
builtin_output_cost > 0
), "Test requires a model with non-zero built-in pricing"
router = Router(
model_list=[
# Deployment A: explicit zero-cost pricing
{
"model_name": "custom-zero-cost-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-1",
},
"model_info": {
"id": "deployment-a-zero-cost",
"input_cost_per_token": 0.0,
"output_cost_per_token": 0.0,
},
},
# Deployment B: no custom pricing, relies on built-in
{
"model_name": "standard-cost-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-2",
},
"model_info": {
"id": "deployment-b-builtin-cost",
},
},
],
)
# Deployment A: should report zero pricing via its unique model_id
info_a = router.get_deployment_model_info(
model_id="deployment-a-zero-cost",
model_name=backend_model,
)
assert info_a is not None
assert info_a["input_cost_per_token"] == 0.0
assert info_a["output_cost_per_token"] == 0.0
# Deployment B: should report built-in pricing, NOT zero
info_b = router.get_deployment_model_info(
model_id="deployment-b-builtin-cost",
model_name=backend_model,
)
assert info_b is not None
assert info_b["input_cost_per_token"] == builtin_input_cost, (
f"Deployment B should use built-in input cost {builtin_input_cost}, "
f"got {info_b['input_cost_per_token']}"
)
assert info_b["output_cost_per_token"] == builtin_output_cost, (
f"Deployment B should use built-in output cost {builtin_output_cost}, "
f"got {info_b['output_cost_per_token']}"
)
def test_should_not_pollute_shared_key_with_custom_nonzero_pricing():
"""
A deployment with custom (non-zero) pricing should not overwrite
the shared backend key's built-in pricing.
"""
backend_model = "vertex_ai/gemini-2.5-flash"
builtin_info = litellm.get_model_info(model=backend_model)
builtin_input_cost = builtin_info["input_cost_per_token"]
router = Router(
model_list=[
# Deployment with custom high pricing
{
"model_name": "expensive-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-3",
},
"model_info": {
"id": "deployment-expensive",
"input_cost_per_token": 0.99,
"output_cost_per_token": 0.99,
},
},
# Deployment relying on built-in pricing
{
"model_name": "standard-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-4",
},
"model_info": {
"id": "deployment-standard",
},
},
],
)
# Custom pricing deployment should see its custom values
info_expensive = router.get_deployment_model_info(
model_id="deployment-expensive",
model_name=backend_model,
)
assert info_expensive is not None
assert info_expensive["input_cost_per_token"] == 0.99
assert info_expensive["output_cost_per_token"] == 0.99
# Standard deployment should still see built-in pricing
info_standard = router.get_deployment_model_info(
model_id="deployment-standard",
model_name=backend_model,
)
assert info_standard is not None
assert info_standard["input_cost_per_token"] == builtin_input_cost, (
f"Standard deployment should use built-in pricing {builtin_input_cost}, "
f"got {info_standard['input_cost_per_token']}"
)
def test_should_store_full_pricing_under_deployment_model_id():
"""
Per-deployment pricing (including zero) should be stored and
retrievable via the unique model_id key in litellm.model_cost.
"""
backend_model = "vertex_ai/gemini-2.5-flash"
router = Router(
model_list=[
{
"model_name": "zero-cost-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-5",
},
"model_info": {
"id": "deployment-zero-check",
"input_cost_per_token": 0.0,
"output_cost_per_token": 0.0,
},
},
],
)
# The model_id entry should exist and have the zero pricing
entry = litellm.model_cost.get("deployment-zero-check")
assert entry is not None, "Deployment should be registered by model_id"
assert entry["input_cost_per_token"] == 0.0
assert entry["output_cost_per_token"] == 0.0
def test_should_preserve_builtin_pricing_regardless_of_deployment_order():
"""
The built-in pricing should be preserved no matter which deployment
is processed first (zero-cost first, or standard first).
"""
backend_model = "vertex_ai/gemini-2.5-flash"
builtin_info = litellm.get_model_info(model=backend_model)
builtin_input_cost = builtin_info["input_cost_per_token"]
builtin_output_cost = builtin_info["output_cost_per_token"]
# Order 1: standard first, then zero-cost
router1 = Router(
model_list=[
{
"model_name": "standard-first",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-6",
},
"model_info": {"id": "order1-standard"},
},
{
"model_name": "zero-cost-second",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-7",
},
"model_info": {
"id": "order1-zero",
"input_cost_per_token": 0.0,
"output_cost_per_token": 0.0,
},
},
],
)
info_std_1 = router1.get_deployment_model_info(
model_id="order1-standard", model_name=backend_model
)
assert info_std_1["input_cost_per_token"] == builtin_input_cost
assert info_std_1["output_cost_per_token"] == builtin_output_cost
# Order 2: zero-cost first, then standard
router2 = Router(
model_list=[
{
"model_name": "zero-cost-first",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-8",
},
"model_info": {
"id": "order2-zero",
"input_cost_per_token": 0.0,
"output_cost_per_token": 0.0,
},
},
{
"model_name": "standard-second",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-9",
},
"model_info": {"id": "order2-standard"},
},
],
)
info_std_2 = router2.get_deployment_model_info(
model_id="order2-standard", model_name=backend_model
)
assert info_std_2["input_cost_per_token"] == builtin_input_cost, (
f"Order should not matter. Expected {builtin_input_cost}, "
f"got {info_std_2['input_cost_per_token']}"
)
assert info_std_2["output_cost_per_token"] == builtin_output_cost, (
f"Order should not matter. Expected {builtin_output_cost}, "
f"got {info_std_2['output_cost_per_token']}"
)
def test_responses_prefix_stripped_alias_registered_for_model_list():
"""
Register ``litellm.model_cost`` under the backend key with ``responses/`` and
under the stripped key (``responses_api_bridge_check`` removes that segment).
"""
uid = "responses-strip-alias-test-a1b2c3d4"
Router(
model_list=[
{
"model_name": "azure-responses-strip-test",
"litellm_params": {
"model": "responses/gpt-strip-test-a1b2c3d4",
"custom_llm_provider": "azure",
"api_key": "fake-key-strip",
},
"model_info": {
"id": uid,
"supports_native_streaming": True,
},
}
],
)
assert "azure/responses/gpt-strip-test-a1b2c3d4" in litellm.model_cost
assert "azure/gpt-strip-test-a1b2c3d4" in litellm.model_cost
assert (
litellm.model_cost["azure/gpt-strip-test-a1b2c3d4"].get(
"supports_native_streaming"
)
is True
)
def test_responses_prefix_stripped_alias_registered_for_add_deployment():
"""Dynamic ``add_deployment`` must mirror ``_create_deployment`` registration."""
uid = "add-dep-responses-strip-e5f6a7b8"
router = Router(model_list=[])
deployment = Deployment(
model_name="dyn-responses-strip",
litellm_params=LiteLLM_Params(
model="responses/gpt-add-strip-e5f6a7b8",
custom_llm_provider="azure",
api_key="fake-key-add",
),
model_info=ModelInfo(id=uid, supports_native_streaming=True),
)
router.add_deployment(deployment=deployment)
assert "azure/responses/gpt-add-strip-e5f6a7b8" in litellm.model_cost
assert "azure/gpt-add-strip-e5f6a7b8" in litellm.model_cost
assert (
litellm.model_cost["azure/gpt-add-strip-e5f6a7b8"].get(
"supports_native_streaming"
)
is True
)