Fix test isolation for test_log_langfuse_v2_handles_null_usage_values

[shin-bot-litellm]

Regression Fix

Failing Job: litellm_mapped_tests_integrations
Caused By: Test isolation issue introduced in 1017c3a
Author: @ishaan-jaff

What Broke

Test test_log_langfuse_v2_handles_null_usage_values fails intermittently when running with parallel test execution.

Error:

AssertionError: Expected 'generation' to have been called once. Called 0 times.

Original Commit LOC

The test originally:

1. Called reset_mock() on setUp's mocks
2. Tried to reconfigure return_value on mocks that had side_effect configured
3. side_effect takes precedence over return_value, causing mock chain issues

This Fix

Create fresh mock objects within the test instead of reusing mocks from setUp:

• Avoids state pollution from setUp's side_effect configuration
• Makes the test deterministic regardless of setUp's mock configuration
• Properly configures the mock chain: client.trace() → trace.generation()

This ensures the test is deterministic in parallel execution environments.

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Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Feb 5, 2026 6:32am

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[greptile-apps]

Greptile Overview

Greptile Summary

This PR fixes a test isolation issue in test_log_langfuse_v2_handles_null_usage_values that caused intermittent failures in parallel test execution.

Root cause: The test's setUp method configures mock_langfuse_client.trace.side_effect (line 56), which persists after reset_mock(). When the failing test tried to reconfigure mocks using return_value, the side_effect took precedence, breaking the mock chain and causing generation to never be called.

Solution: Create fresh MagicMock objects scoped to the test instead of reusing setUp's mocks. This eliminates state pollution and ensures the mock chain works correctly: client.trace() → trace.generation() → assertions pass.

Changes:

• Removed reset_mock() calls that were ineffective
• Created fresh mock_client, mock_trace, mock_generation, and mock_span within the test
• Properly configured mock chain with return_value instead of fighting side_effect
• Updated assertions to use the new local mocks instead of self.mock_langfuse_*

Confidence Score: 5/5

• Safe to merge - this is a focused test fix with no production code changes
• The fix correctly addresses a well-understood mock isolation issue by replacing shared mocks with test-scoped mocks, eliminating the side_effect vs return_value conflict that caused test flakiness
• No files require special attention

Important Files Changed

Filename	Overview
tests/test_litellm/integrations/test_langfuse.py	Replaced shared mocks with fresh test-scoped mocks to fix race condition caused by side_effect precedence over return_value

Sequence Diagram

sequenceDiagram
    participant Test as test_log_langfuse_v2_handles_null_usage_values
    participant Logger as LangFuseLogger
    participant MockClient as mock_client
    participant MockTrace as mock_trace
    participant MockGen as mock_generation
    
    Note over Test: OLD: Used setUp's mocks with side_effect
    Note over Test: NEW: Creates fresh mocks
    
    Test->>Test: Create mock_client, mock_trace, mock_generation
    Test->>Test: Configure chain: client.trace() → trace
    Test->>Test: Configure chain: trace.generation() → generation
    Test->>Logger: Assign mock_client to logger.Langfuse
    
    Test->>Logger: Call _log_langfuse_v2(response_obj with null usage)
    Logger->>MockClient: trace(name, metadata, ...)
    MockClient-->>Logger: Returns mock_trace
    Logger->>MockTrace: generation(usage={prompt_tokens:0, ...})
    MockTrace-->>Logger: Returns mock_generation
    
    Test->>MockClient: assert trace.assert_called()
    Test->>MockTrace: assert generation.assert_called_once()
    Test->>Test: Verify usage values converted None→0

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