Flatpak CommandRunner Migration (Issue #20 Part 3)

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Summary

Migrate Flatpak package manager from direct exec.Command calls to unified CommandRunner interface for consistent, testable command execution architecture.

This is Part 3 of Issue #20 - CommandRunner Pattern Implementation

Background

Complete the CommandRunner migration initiative by implementing unified command execution patterns for Flatpak, achieving full architectural consistency across all package managers.

Current State

• APT: ✅ Uses CommandRunner (Issue APT CommandRunner Migration (Issue #20 Part 1) #27 completed)
• YUM: ✅ Uses CommandRunner (already implemented)
• Snap: Direct exec.Command calls (Issue Snap CommandRunner Migration (Issue #20 Part 2) #28 - Part 2)
• Flatpak: Uses direct exec.Command calls

Scope

• Flatpak package manager migration from exec.Command to CommandRunner
• Constructor standardization following established APT/YUM/Snap patterns
• Dependency injection for comprehensive testing capabilities
• Test coverage expansion (currently 0% coverage for Flatpak)

Technical Implementation

CommandRunner Integration

• Replace all exec.Command calls with CommandRunner interface
• Implement automatic LC_ALL=C handling for consistent English output
• Add built-in interactive mode support via RunInteractive()
• Enable dependency injection for testing

Constructor Pattern

Following established standardization:

• NewPackageManager() - Production use with default CommandRunner
• NewPackageManagerWithCustomRunner() - Testing use with mock CommandRunner

Testing Infrastructure

• Implement comprehensive mock-based testing
• Add environment variable tracking capabilities
• Create cross-platform test scenarios
• Achieve significant test coverage improvement (currently 0%)

Benefits

Architecture Benefits

• ✅ Complete consistency - All package managers use same CommandRunner pattern
• ✅ Automatic LC_ALL=C - No manual environment setup needed
• ✅ Built-in interactive support - Proper stdin/stdout/stderr handling
• ✅ Unified codebase - Same patterns and interfaces everywhere

Testing Benefits

• ✅ Consistent testing - Same mocking approach across all package managers
• ✅ Environment testing - Built-in environment variable verification
• ✅ Cross-platform testing - Same tests work across all environments
• ✅ Full coverage - All command execution paths testable

Project Completion

• ✅ Issue Implement CommandRunner pattern for unified testable package manager operations #20 completion - All package managers migrated to CommandRunner
• ✅ Architectural consistency - Unified command execution across entire codebase
• ✅ Testing maturity - Comprehensive test coverage for all package managers

Acceptance Criteria

• Flatpak migrated from direct exec.Command to CommandRunner
• Constructor naming follows established patterns
• Dependency injection implemented for testing
• Comprehensive test coverage added (target: >80%)
• LC_ALL=C automatically handled
• Interactive mode works consistently
• All existing functionality preserved
• Documentation updated
• Issue Implement CommandRunner pattern for unified testable package manager operations #20 marked as complete

Priority

Medium Priority - Final piece of architectural consistency improvement.

Dependencies

• Should follow patterns established in Issue APT CommandRunner Migration (Issue #20 Part 1) #27 (APT) and Issue Snap CommandRunner Migration (Issue #20 Part 2) #28 (Snap)
• Can be implemented in parallel with Issue Snap CommandRunner Migration (Issue #20 Part 2) #28 (Snap)

Related Issues

• Completes Issue Implement CommandRunner pattern for unified testable package manager operations #20 - CommandRunner Pattern Implementation
• Part of the same initiative as Issue APT CommandRunner Migration (Issue #20 Part 1) #27 (APT) and Issue Snap CommandRunner Migration (Issue #20 Part 2) #28 (Snap)

Implementation Notes

• Follow proven patterns from APT migration (Issue APT CommandRunner Migration (Issue #20 Part 1) #27)
• Leverage existing CommandRunner interface and MockCommandRunner
• Maintain backward compatibility during migration
• Use established testing frameworks and patterns
• This completes the full CommandRunner migration across all package managers

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Update: Test Coverage Goals Added

Additional Scope: This issue should also address Flatpak's 0% test coverage.

Current Status

• Flatpak test coverage: 0% (needs comprehensive test suite)
• APT test coverage: 60% (good baseline achieved)
• YUM test coverage: 69.4% (good, with some gaps addressed in Issue Improve YUM test coverage for ListInstalled, Clean, and GetPackageInfo methods #32)
• Snap test coverage: 0% (being addressed in Issue Snap CommandRunner Migration (Issue #20 Part 2) #28)

Enhanced Acceptance Criteria

In addition to CommandRunner migration, this issue should include:

• Create comprehensive test suite for Flatpak package manager
• Target test coverage: >80% (matching or exceeding APT/YUM)
• Test all core methods: Install, Remove, Find, ListInstalled, etc.
• Mock-based testing: Use MockCommandRunner for cross-platform testing
• Fixture-based tests: Use real flatpak command outputs where appropriate
• Behavior testing: Follow testing philosophy focusing on contracts

Project Impact

This combined approach will:

1. Complete Issue Implement CommandRunner pattern for unified testable package manager operations #20: All package managers using CommandRunner
2. Achieve test parity: All PMs with >60% coverage
3. Enable reliable CI/CD: Full test coverage across all package managers
4. Finish architectural vision: Consistent patterns + comprehensive testing

Final Milestone

Upon completion of Issue #29, the project will have:

• ✅ 4/4 package managers using CommandRunner architecture
• ✅ 4/4 package managers with comprehensive test coverage
• ✅ Complete architectural consistency across the entire codebase