MCP Debugger

# tests/unit/utils/language-config.test.ts @source-hash: 42777cb854983c43 @generated: 2026-02-10T00:41:36Z ## Purpose Unit test suite for language configuration utilities that handle environment-based language disabling functionality. Tests the parsing and querying of disabled languages from the `DEBUG_MCP_DISABLE_LANGUAGES` environment variable. ## Test Structure - **Main test suite** (L6-41): "language configuration helpers" - comprehensive testing of language configuration functions - **Environment setup/teardown** (L7-13): Preserves and restores original `process.env` state using `beforeEach`/`afterEach` hooks - **Original environment backup** (L4): Captures initial environment state for restoration ## Tested Functions Tests two key utilities from `../../../src/utils/language-config.js`: - `getDisabledLanguages()`: Parses comma-separated language list from environment variable - `isLanguageDisabled(language)`: Checks if specific language is in disabled set ## Test Cases ### Environment Variable Parsing (L15-21) Tests `getDisabledLanguages()` with various input formats: - Handles mixed case ("python, Rust") - Trims whitespace around entries - Filters out empty strings from extra commas - Returns normalized Set with lowercase entries ### Missing Environment Variable (L23-26) Verifies graceful handling when `DEBUG_MCP_DISABLE_LANGUAGES` is undefined: - Deletes environment variable - Expects empty Set return value ### Case-Insensitive Language Detection (L28-34) Tests `isLanguageDisabled()` behavior: - Environment contains "PYTHON,RUST" (uppercase) - Queries with mixed case ("python", "Rust") return `true` - Non-disabled language ("mock") returns `false` ### Input Validation (L36-40) Tests robustness with invalid inputs: - Empty string returns `false` - `null` (cast as string) returns `false` - Maintains type safety despite forced casting ## Key Patterns - **Environment isolation**: Each test runs with clean environment state - **Case normalization**: Tests demonstrate case-insensitive language matching - **Whitespace handling**: Validates robust parsing of user-provided environment values - **Edge case coverage**: Tests both missing data and invalid input scenarios