diff --git a/tests/test_litellm/test_cost_calculator.py b/tests/test_litellm/test_cost_calculator.py
index e49a3327e92..40a21af84bb 100644
--- a/tests/test_litellm/test_cost_calculator.py
+++ b/tests/test_litellm/test_cost_calculator.py
@@ -124,12 +124,12 @@ def test_custom_pricing_skips_provider_response_cost():
     )
 
     # Must use custom pricing, NOT provider response cost
-    assert result != provider_usd_cost, (
-        f"Should not use provider response cost ({provider_usd_cost})"
-    )
-    assert result == pytest.approx(expected_custom_cost), (
-        f"Got {result}, expected {expected_custom_cost} from custom pricing"
-    )
+    assert (
+        result != provider_usd_cost
+    ), f"Should not use provider response cost ({provider_usd_cost})"
+    assert result == pytest.approx(
+        expected_custom_cost
+    ), f"Got {result}, expected {expected_custom_cost} from custom pricing"
 
 
 def test_provider_response_cost_used_when_no_custom_pricing():
@@ -140,9 +140,7 @@ def test_provider_response_cost_used_when_no_custom_pricing():
 
     class MockResponse(BaseModel):
         _hidden_params = {
-            "additional_headers": {
-                "llm_provider-x-litellm-response-cost": 0.0000024
-            }
+            "additional_headers": {"llm_provider-x-litellm-response-cost": 0.0000024}
         }
 
     result = response_cost_calculator(
@@ -156,9 +154,7 @@ def test_provider_response_cost_used_when_no_custom_pricing():
         custom_pricing=False,
     )
 
-    assert result == 0.0000024, (
-        f"Should use provider response cost, got {result}"
-    )
+    assert result == 0.0000024, f"Should use provider response cost, got {result}"
 
 
 def test_custom_pricing_without_provider_response_cost():
@@ -211,9 +207,9 @@ def test_custom_pricing_without_provider_response_cost():
     expected_cost = (
         prompt_tokens * custom_input_cost + completion_tokens * custom_output_cost
     )
-    assert result == pytest.approx(expected_cost), (
-        f"Got {result}, expected {expected_cost} from custom pricing"
-    )
+    assert result == pytest.approx(
+        expected_cost
+    ), f"Got {result}, expected {expected_cost} from custom pricing"
 
 
 def test_cost_calculator_with_usage(monkeypatch):
@@ -272,6 +268,7 @@ def test_cost_calculator_with_usage(monkeypatch):
 
     # Invalidate caches after modifying litellm.model_cost
     from litellm.utils import _invalidate_model_cost_lowercase_map
+
     _invalidate_model_cost_lowercase_map()
 
     result = response_cost_calculator(
@@ -677,9 +674,7 @@ def test_azure_audio_output_cost_calculation():
     model_info = litellm.get_model_info("azure/gpt-audio-2025-08-28")
 
     # Calculate expected cost
-    expected_input_cost = (
-        model_info["input_cost_per_token"] * 17  # text tokens
-    )
+    expected_input_cost = model_info["input_cost_per_token"] * 17  # text tokens
     expected_output_cost = (
         model_info["output_cost_per_token"] * 110  # text tokens
         + model_info["output_cost_per_audio_token"] * 482  # audio tokens
@@ -691,14 +686,14 @@ def test_azure_audio_output_cost_calculation():
     wrong_total_cost = expected_input_cost + wrong_output_cost
 
     # Verify audio tokens are NOT charged at text rate (the bug)
-    assert abs(cost - wrong_total_cost) > 0.001, (
-        "Bug: Audio tokens are being charged at text token rate"
-    )
+    assert (
+        abs(cost - wrong_total_cost) > 0.001
+    ), "Bug: Audio tokens are being charged at text token rate"
 
     # Verify cost matches
-    assert abs(cost - expected_total_cost) < 0.0000001, (
-        f"Expected cost {expected_total_cost}, got {cost}"
-    )
+    assert (
+        abs(cost - expected_total_cost) < 0.0000001
+    ), f"Expected cost {expected_total_cost}, got {cost}"
 
 
 def test_default_image_cost_calculator(monkeypatch):
@@ -1205,12 +1200,12 @@ def test_azure_ai_cache_cost_calculation():
     print(f"Output cost: {output_cost}, Expected: {expected_output_cost}")
     print(f"Total cost: {total_cost}")
 
-    assert abs(input_cost - expected_input_cost) < 1e-10, (
-        f"Input cost mismatch: got {input_cost}, expected {expected_input_cost}"
-    )
-    assert abs(output_cost - expected_output_cost) < 1e-10, (
-        f"Output cost mismatch: got {output_cost}, expected {expected_output_cost}"
-    )
+    assert (
+        abs(input_cost - expected_input_cost) < 1e-10
+    ), f"Input cost mismatch: got {input_cost}, expected {expected_input_cost}"
+    assert (
+        abs(output_cost - expected_output_cost) < 1e-10
+    ), f"Output cost mismatch: got {output_cost}, expected {expected_output_cost}"
 
 
 def test_cost_discount_vertex_ai():
@@ -2078,7 +2073,9 @@ def test_gemini_implicit_caching_cost_calculation():
         f"Cached tokens may not be using reduced pricing."
     )
 
-    print("✅ Issue #16341 fix verified: Gemini implicit caching cost calculated correctly")
+    print(
+        "✅ Issue #16341 fix verified: Gemini implicit caching cost calculated correctly"
+    )
 
 
 def test_additional_costs_only_for_azure_ai():