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>

tests/unit_tests/pipeline/test_ratelimit.py

@@ -0,0 +1,109 @@
+"""
+RateLimit stage unit tests
+
+Tests the actual RateLimit implementation from pkg.pipeline.ratelimit
+"""
+
+import pytest
+from unittest.mock import AsyncMock, Mock, patch
+from importlib import import_module
+import langbot_plugin.api.entities.builtin.provider.session as provider_session
+
+
+def get_modules():
+    """Lazy import to ensure proper initialization order"""
+    # Import pipelinemgr first to trigger proper stage registration
+    pipelinemgr = import_module('pkg.pipeline.pipelinemgr')
+    ratelimit = import_module('pkg.pipeline.ratelimit.ratelimit')
+    entities = import_module('pkg.pipeline.entities')
+    algo_module = import_module('pkg.pipeline.ratelimit.algo')
+    return ratelimit, entities, algo_module
+
+
+@pytest.mark.asyncio
+async def test_require_access_allowed(mock_app, sample_query):
+    """Test RequireRateLimitOccupancy allows access when rate limit is not exceeded"""
+    ratelimit, entities, algo_module = get_modules()
+
+    sample_query.launcher_type = provider_session.LauncherTypes.PERSON
+    sample_query.launcher_id = '12345'
+    sample_query.pipeline_config = {}
+
+    # Create mock algorithm that allows access
+    mock_algo = Mock(spec=algo_module.ReteLimitAlgo)
+    mock_algo.require_access = AsyncMock(return_value=True)
+    mock_algo.initialize = AsyncMock()
+
+    stage = ratelimit.RateLimit(mock_app)
+
+    # Patch the algorithm selection to use our mock
+    with patch.object(algo_module, 'preregistered_algos', []):
+        stage.algo = mock_algo
+
+    result = await stage.process(sample_query, 'RequireRateLimitOccupancy')
+
+    assert result.result_type == entities.ResultType.CONTINUE
+    assert result.new_query == sample_query
+    mock_algo.require_access.assert_called_once_with(
+        sample_query,
+        'person',
+        '12345'
+    )
+
+
+@pytest.mark.asyncio
+async def test_require_access_denied(mock_app, sample_query):
+    """Test RequireRateLimitOccupancy denies access when rate limit is exceeded"""
+    ratelimit, entities, algo_module = get_modules()
+
+    sample_query.launcher_type = provider_session.LauncherTypes.PERSON
+    sample_query.launcher_id = '12345'
+    sample_query.pipeline_config = {}
+
+    # Create mock algorithm that denies access
+    mock_algo = Mock(spec=algo_module.ReteLimitAlgo)
+    mock_algo.require_access = AsyncMock(return_value=False)
+    mock_algo.initialize = AsyncMock()
+
+    stage = ratelimit.RateLimit(mock_app)
+
+    # Patch the algorithm selection to use our mock
+    with patch.object(algo_module, 'preregistered_algos', []):
+        stage.algo = mock_algo
+
+    result = await stage.process(sample_query, 'RequireRateLimitOccupancy')
+
+    assert result.result_type == entities.ResultType.INTERRUPT
+    assert result.user_notice != ''
+    mock_algo.require_access.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_release_access(mock_app, sample_query):
+    """Test ReleaseRateLimitOccupancy releases rate limit occupancy"""
+    ratelimit, entities, algo_module = get_modules()
+
+    sample_query.launcher_type = provider_session.LauncherTypes.PERSON
+    sample_query.launcher_id = '12345'
+    sample_query.pipeline_config = {}
+
+    # Create mock algorithm
+    mock_algo = Mock(spec=algo_module.ReteLimitAlgo)
+    mock_algo.release_access = AsyncMock()
+    mock_algo.initialize = AsyncMock()
+
+    stage = ratelimit.RateLimit(mock_app)
+
+    # Patch the algorithm selection to use our mock
+    with patch.object(algo_module, 'preregistered_algos', []):
+        stage.algo = mock_algo
+
+    result = await stage.process(sample_query, 'ReleaseRateLimitOccupancy')
+
+    assert result.result_type == entities.ResultType.CONTINUE
+    assert result.new_query == sample_query
+    mock_algo.release_access.assert_called_once_with(
+        sample_query,
+        'person',
+        '12345'
+    )