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# tests/unit/shared/filesystem.test.ts @source-hash: 99d0b1e6662ee880 @generated: 2026-02-10T00:41:33Z ## Purpose Unit tests for the NodeFileSystem implementation and default filesystem management functionality. Tests filesystem abstraction layer that provides safe defaults when underlying Node.js fs operations fail. ## Test Structure - **Main test suite** (L10-53): "NodeFileSystem" - Tests the NodeFileSystem class behavior - **Setup/Teardown** (L11-13): Restores all Vitest mocks after each test ## Key Test Cases ### Basic Delegation Test (L15-22) Tests that NodeFileSystem properly delegates to Node.js fs module: - Creates NodeFileSystem instance (L16) - Uses real package.json as test fixture (L17) - Verifies existsSync returns true for existing file (L19) - Verifies readFileSync returns content containing expected JSON property (L20-21) ### Error Handling Test (L24-38) Tests safe defaults when fs operations throw errors: - Mocks fs methods to throw errors (L27-34) - Uses type assertion to access private fs property (L27) - Verifies existsSync returns false on error (L36) - Verifies readFileSync returns empty string on error (L37) ### Default Filesystem Override Test (L40-52) Tests the global filesystem instance management: - Creates stub filesystem with mocked methods (L41-44) - Tests setDefaultFileSystem() and getDefaultFileSystem() functions (L46-48) - Resets to real implementation to prevent test pollution (L50-51) ## Dependencies - **Vitest**: Testing framework with mocking capabilities - **Node.js fs/path**: Standard filesystem modules - **../../../packages/shared/src/interfaces/filesystem.js**: Source module under test ## Key Patterns - Uses real filesystem operations for integration-style testing - Employs type assertions to access private members for error simulation - Includes explicit cleanup to prevent cross-test contamination - Tests both happy path and error scenarios for robust coverage