Gap Analysis: Complete Sequence Patterns Analyzer Implementation (InSequence/MockSequence)

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Background

This issue provides a gap analysis for completing the sequence patterns analyzer implementation as originally requested in issue #576. PR #581 successfully implemented the foundational SetupSequence validation (Moq1207), but significant functionality remains for full sequence pattern support.

What Was Completed in PR #581

✅ SetupSequence Basic Validation (Moq1207)

• Validates SetupSequence calls are only used on overridable members
• Comprehensive test coverage with 40+ test cases
• Supports Moq versions 4.8.2 and 4.18.4+
• Complete documentation and error messaging

Gap Analysis: Remaining Work

Based on the original acceptance criteria from #576, the following functionality still needs implementation:

🔄 Epic 1: InSequence/MockSequence Coordination Validation

User Story: As a developer using MockSequence with InSequence, I want analyzer validation to ensure proper sequence coordination, so that my sequential mock setups behave predictably.

INVEST Analysis:

• Independent: Can be developed separately from other sequence validations
• Negotiable: Implementation approach (cross-statement vs single-call analysis) is flexible
• Valuable: Prevents common MockSequence misuse patterns that cause test failures
• Estimable: Moderate complexity - requires cross-statement analysis infrastructure
• Small: Can be broken into sub-tasks (detection, validation, diagnostics)
• Testable: Clear success criteria with concrete code examples

Acceptance Criteria:

• [ ] Analyzer detects MockSequence instantiation patterns
• [ ] Validates that InSequence() calls reference the same MockSequence instance
• [ ] Ensures proper ordering constraints are maintained
• [ ] Provides clear diagnostic messages for sequence coordination errors
• [ ] Handles both valid sequence patterns and common anti-patterns

Technical Requirements:

🔄 Epic 2: Incomplete Sequence Configuration Detection

User Story: As a developer setting up mock sequences, I want analyzer warnings for incomplete configurations, so that I avoid runtime surprises from unconfigured sequence steps.

INVEST Analysis:

• Independent: Standalone validation separate from coordination logic
• Negotiable: Warning vs error severity is configurable
• Valuable: Prevents subtle test failures from incomplete sequence setups
• Estimable: Medium complexity - requires tracking sequence call chains
• Small: Focused on single sequence completion validation
• Testable: Can verify detection of various incomplete patterns

Acceptance Criteria:

• [ ] Detects SetupSequence calls without subsequent Returns/Throws configuration
• [ ] Identifies partially configured sequence chains
• [ ] Provides actionable diagnostic messages with completion suggestions
• [ ] Handles edge cases (async sequences, complex return types)

Technical Requirements:

🔄 Epic 3: Mixed Returns/Throws Sequence Validation

User Story: As a developer configuring complex sequences, I want validation of mixed Returns/Throws patterns, so that I can ensure my sequence configurations are semantically correct.

INVEST Analysis:

• Independent: Can be implemented without dependencies on other epics
• Negotiable: Validation rules can be adjusted based on Moq version capabilities
• Valuable: Prevents invalid sequence configurations that fail at runtime
• Estimable: Low-medium complexity - builds on existing SetupSequence infrastructure
• Small: Focused validation of method call patterns
• Testable: Clear examples of valid/invalid mixed patterns

Acceptance Criteria:

• [ ] Validates Returns/Throws method chaining patterns
• [ ] Ensures type compatibility in sequence return chains
• [ ] Handles async method sequence patterns (Task/ValueTask)
• [ ] Provides specific guidance for fixing sequence type mismatches

Implementation Strategy

Phase 1: Infrastructure (Epic 1 Foundation)

• Extend MoqKnownSymbols for MockSequence and InSequence symbols
• Develop cross-statement analysis capabilities
• Create sequence relationship tracking utilities

Phase 2: Core Validations (Epics 1-3)

• Implement coordination validation analyzer
• Add incomplete configuration detection
• Extend mixed pattern validation

Phase 3: Integration & Polish

• Comprehensive test coverage across all Moq versions
• Documentation updates for new analyzer rules
• Performance optimization for cross-statement analysis

Technical Considerations

• Cross-statement Analysis: Unlike the current SetupSequence validation, InSequence coordination requires analyzing relationships between multiple statements
• Symbol Tracking: Need to track MockSequence instance references across method calls
• Performance: Cross-statement analysis must be optimized to avoid significant compilation slowdown
• Moq Version Compatibility: Ensure support for both older (4.8.2) and newer (4.18.4+) Moq versions

Success Metrics

• [ ] All acceptance criteria from original issue #576 completed
• [ ] Zero regressions in existing analyzer functionality
• [ ] Comprehensive test coverage (>95%) for new analyzers
• [ ] Performance impact <5% increase in analysis time
• [ ] Clear diagnostic messages with actionable guidance

References

• Original Issue: #576 - Implement Sequence Patterns Analyzer (SetupSequence/InSequence/MockSequence)
• Foundational PR: #581 - feat: Implement SetupSequence validation analyzer (Moq1207)
• Related: #434 - Parent issue for Moq sequence patterns analysis

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Estimated Effort: 3-4 weeks for experienced analyzer developer Priority: Medium - builds on solid foundation from PR #581 Assignee: @rjmurillo