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+# CCS Test Suite
+
+## Organization
+
+- `native/` - Traditional installation (curl|bash, irm|iex)
+  - `unix/` - Unix/Linux/macOS native tests
+  - `windows/` - Windows PowerShell tests
+- `npm/` - npm package tests
+  - `postinstall.test.js` - Postinstall behavior tests
+  - `cli.test.js` - CLI argument parsing tests
+  - `cross-platform.test.js` - Cross-platform compatibility tests
+- `unit/` - Node.js unit tests
+- `integration/` - Integration tests
+- `shared/` - Shared utilities and test data
+
+## Running Tests
+
+- All tests: `npm test`
+- npm package tests only: `npm run test:npm`
+- Native installation tests only: `npm run test:native`
+- Unit tests only: `npm run test:unit`
+- Integration tests only: `npm run test:integration`
+- Master test suite (backward compatible): `npm run test:edge-cases`
+
+## Test Structure
+
+### Native Tests
+Test the traditional installation methods where CCS is installed via:
+- Unix/Linux/macOS: `curl | bash`
+- Windows: `irm | iex` (PowerShell)
+
+These tests use bash/PowerShell scripts and test the `lib/ccs` and `lib/ccs.ps1` files.
+
+### npm Tests
+Test the npm package installation where CCS is installed via:
+- npm: `npm install -g @kaitranntt/ccs`
+
+These tests use Node.js/mocha framework and test the `bin/ccs.js` file.
+
+### Shared Utilities
+Common test code, data, and helper functions are stored in `shared/` to avoid duplication across test suites.
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+# npm Package Tests
+
+Tests for npm installation method of CCS.
+
+## Files
+
+- `postinstall.test.js` - Postinstall behavior and configuration creation
+- `cli.test.js` - CLI argument parsing and profile handling
+- `cross-platform.test.js` - Cross-platform compatibility tests
+
+## Running
+
+```bash
+# Run only npm tests
+npm run test:npm
+
+# Run with verbose output
+npm run test:npm -- --reporter spec
+
+# Run specific test file
+npx mocha tests/npm/postinstall.test.js
+```
+
+## Test Coverage
+
+These tests cover:
+- Postinstall script behavior (Section 10 from original edge-cases.sh)
+- CLI argument parsing for npm package
+- Cross-platform path handling
+- Configuration file creation and management
+- Profile system functionality
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