feat: add comprehensive unit tests for pipeline stages (#1701)

* feat: add comprehensive unit tests for pipeline stages

* fix: deps install in ci

* ci: use venv

* ci: run run_tests.sh

* fix: resolve circular import issues in pipeline tests

Update all test files to use lazy imports via importlib.import_module()
to avoid circular dependency errors. Fix mock_conversation fixture to
properly mock list.copy() method.

Changes:
- Use lazy import pattern in all test files
- Fix conftest.py fixture for conversation messages
- Add integration test file for full import tests
- Update documentation with known issues and workarounds

Tests now successfully avoid circular import errors while maintaining
full test coverage of pipeline stages.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* docs: add comprehensive testing summary

Document implementation details, challenges, solutions, and future
improvements for the pipeline unit test suite.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor: rewrite unit tests to test actual pipeline stage code

Rewrote unit tests to properly test real stage implementations instead of
mock logic:

- Test actual BanSessionCheckStage with 7 test cases (100% coverage)
- Test actual RateLimit stage with 3 test cases (70% coverage)
- Test actual PipelineManager with 5 test cases
- Use lazy imports via import_module to avoid circular dependencies
- Import pipelinemgr first to ensure proper stage registration
- Use Query.model_construct() to bypass Pydantic validation in tests
- Remove obsolete pure unit tests that didn't test real code
- All 20 tests passing with 48% overall pipeline coverage

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* test: add unit tests for GroupRespondRuleCheckStage

Added comprehensive unit tests for resprule stage:

- Test person message skips rule check
- Test group message with no matching rules (INTERRUPT)
- Test group message with matching rule (CONTINUE)
- Test AtBotRule removes At component correctly
- Test AtBotRule when no At component present

Coverage: 100% on resprule.py and atbot.py
All 25 tests passing with 51% overall pipeline coverage

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor: restructure tests to tests/unit_tests/pipeline

Reorganized test directory structure to support multiple test categories:

- Move tests/pipeline → tests/unit_tests/pipeline
- Rename .github/workflows/pipeline-tests.yml → run-tests.yml
- Update run_tests.sh to run all unit tests (not just pipeline)
- Update workflow to trigger on all pkg/** and tests/** changes
- Coverage now tracks entire pkg/ module instead of just pipeline

This structure allows for easy addition of more unit tests for other
modules in the future.

All 25 tests passing with 21% overall pkg coverage.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* ci: upload codecov report

* ci: codecov file

* ci: coverage.xml

---------

Co-authored-by: Claude <noreply@anthropic.com>

pytest.ini

@@ -0,0 +1,39 @@
+[pytest]
+# Test discovery patterns
+python_files = test_*.py
+python_classes = Test*
+python_functions = test_*
+
+# Test paths
+testpaths = tests
+
+# Asyncio configuration
+asyncio_mode = auto
+
+# Output options
+addopts =
+    -v
+    --strict-markers
+    --tb=short
+    --disable-warnings
+
+# Markers
+markers =
+    asyncio: mark test as async
+    unit: mark test as unit test
+    integration: mark test as integration test
+    slow: mark test as slow running
+
+# Coverage options (when using pytest-cov)
+[coverage:run]
+source = pkg
+omit =
+    */tests/*
+    */test_*.py
+    */__pycache__/*
+    */site-packages/*
+
+[coverage:report]
+precision = 2
+show_missing = True
+skip_covered = False