tests: langchain test fixes

[TejasGhatte]

Summary

OpenAI chat streams begin with a role-only delta ({"role":"assistant","content":""}) before any content arrives. The streaming loop previously required non-empty content (or reasoning/refusal/annotations/tool calls) before forwarding a chunk, so this initial delta was silently dropped. Strict streaming clients that rely on the role delta to assign the role of the accumulated message would receive an incomplete stream. This PR forwards the role-only delta and adds a dedicated test to assert that behavior.

Changes

• Extended the chunk-forwarding condition in HandleOpenAIChatCompletionStreaming to also forward deltas that carry a non-nil Role field, regardless of whether content is present.
• Updated the raw-response ordering test fixture (rawRoleOnlyFrame) to include "content":"" so it matches the real OpenAI wire format and is now forwarded as a semantic chunk rather than buffered.
• Removed the role-only frame from the list of "dropped frames" in the raw-response capture test comments, since it is no longer dropped.
• Added TestChatStreamForwardsRoleOnlyDelta to assert that the first forwarded delta carries role:"assistant" with empty content and that the second carries the actual text.
• Updated the thinking model in the Python integration config from o1 to gpt-5.5.
• Set asyncio_mode = "auto" in pyproject.toml so LangChain's unmarked async tests run under pytest-asyncio without requiring strict-mode markers.
• Refactored test_18_multi_provider_langchain_comparison to use config-driven model names, surface per-provider errors in the assertion message, and correctly extract content strings for the uniqueness check.

Type of change

• Bug fix
• Feature
• Refactor
• Documentation
• Chore/CI

Affected areas

• Core (Go)
• Transports (HTTP)
• Providers/Integrations
• Plugins
• UI (React)
• Docs

How to test

# Run the streaming unit tests
go test ./core/providers/openai/... -run TestChatStream -v

# Confirm the new role-only forwarding test passes
go test ./core/providers/openai/... -run TestChatStreamForwardsRoleOnlyDelta -v

# Confirm raw-response ordering tests still pass
go test ./core/providers/openai/... -run TestChatStreamRawResponse -v

# Python integration tests
cd tests/integrations/python
uv run pytest tests/test_langchain.py -v

Breaking changes

• Yes
• No

Related issues

Closes #7144

Security considerations

None.

Checklist

• I read docs/contributing/README.md and followed the guidelines
• I added/updated tests where appropriate
• I updated documentation where needed
• I verified builds succeed (Go and UI)
• I verified the CI pipeline passes locally if applicable

[coderabbitai]

📝 Summary

Summary by CodeRabbit

• Bug Fixes

  • OpenAI chat streaming now forwards initial assistant role updates, including updates without message content, in the correct order.
  • Improved handling of streamed responses containing metadata-only frames.

• Tests

  • Expanded streaming coverage for role-only assistant updates.
  • Improved multi-provider integration validation and asynchronous test execution.
  • Updated Azure integration coverage to use the current thinking model.

Walkthrough

OpenAI chat streaming now forwards initial role-only assistant deltas. Tests verify forwarding and raw-response ordering. Python integration tests use configured provider models, automatic async handling, shared routing, normalized responses, and provider-specific error reporting.

Changes

OpenAI streaming

Layer / File(s)	Summary
Role-only delta forwarding core/providers/openai/openai.go	Chat streaming forwards non-nil role deltas. Finish-only and usage-only frames remain buffered.
Streaming behavior validation core/providers/openai/streamtruncation_test.go	Tests cover empty role-only content, raw-response ordering, and forwarding before the "hello" content delta.

Python integration tests

Layer / File(s)	Summary
Provider comparison test configuration tests/integrations/python/config.yml, tests/integrations/python/pyproject.toml, tests/integrations/python/tests/test_langchain.py	The tests use configured provider models, automatic async handling, shared routing, normalized responses, and collected provider errors.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested reviewers: akshaydeo

Merge Risk: 🔵 Low · up to d213f

A supported Mistral deployment using a different model may not be exercised by this integration comparison, while the suite can still pass. Configure its model before merge or explicitly accept this test-coverage gap.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	The changed files implement OpenAI stream-delta forwarding and tests, change the Azure integration model, enable automatic pytest asyncio mode, and revise LangChain provider comparison tests. These ch…	Remove the unrelated streaming and LangChain test changes from this issue, or link them to an issue that requires those test fixes. Keep changes for issue #123 limited to File API implementation and its automated tests.
Linked Issues check	❓ Inconclusive	Issue #123 requires File API support for providers such as OpenAI or Anthropic, including file upload use cases. The reviewed changes address OpenAI streaming deltas and LangChain integration configur…	Inspect the existing provider endpoint routing and file API tests for OpenAI and Anthropic. This evidence is required to determine whether the existing implementation satisfies issue #123.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 3 files. (2 skipped: 2 …
Title check	✅ Passed	The title accurately identifies the LangChain integration test fixes, which are part of the changes. It does not mention the main OpenAI role-only streaming fix, so it is somewhat incomplete but remai…
Description check	✅ Passed	The description is complete and follows the repository template. It explains the OpenAI streaming bug, lists the code and test changes, identifies affected areas, provides test commands, records the b…

Full details: Linked Issues check

Explanation

Issue #123 requires File API support for providers such as OpenAI or Anthropic, including file upload use cases. The reviewed changes address OpenAI streaming deltas and LangChain integration configuration. They add no file API implementation or file API tests. The reviewed head contains core/providers/openai/files.go, core/providers/openai/files_test.go, core/providers/anthropic/files.go, and core/providers/anthropic/file_test.go; openai/files.go contains file response types and conversion functions. The available evidence does not establish whether complete upload, retrieval, listing, and deletion endpoint support already exists elsewhere.

Full details: Out of Scope Changes check

Explanation

The changed files implement OpenAI stream-delta forwarding and tests, change the Azure integration model, enable automatic pytest asyncio mode, and revise LangChain provider comparison tests. These changes have no demonstrated connection to the File API objectives in issue #123.

• Fix all pre-merge checks with AI

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 09-15-tests_langchain_test_fixes

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[TejasGhatte]

• tests: langchain test fixes #7193 👈 (View in Graphite)
• dev

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[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@tests/integrations/python/tests/test_langchain.py`:
- Line 946: Replace the hard-coded Mistral model in the relevant test setup with
get_provider_model("mistral", "chat"), and add the corresponding
providers.mistral.chat configuration entry in config.yml so deployments can
select their supported model.

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📥 Commits

Reviewing files that changed from the base of the PR and between add4f40 and d213f90.

📒 Files selected for processing (5)

• core/providers/openai/openai.go
• core/providers/openai/streamtruncation_test.go
• tests/integrations/python/config.yml
• tests/integrations/python/pyproject.toml
• tests/integrations/python/tests/test_langchain.py

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[akshaydeo]

Merge activity

• Sep 15, 3:48 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Sep 15, 3:49 PM UTC: @akshaydeo merged this pull request with Graphite.