♻️ refactor(config.ts): Addition of UnitTest environment and unittest for commands/config.ts#getConfig (#330)

* feat(jest.config.ts): update jest preset for TS ESM support and ignore patterns
feat(package.json): add test:unit script with NODE_OPTIONS for ESM
refactor(src/commands/config.ts): improve dotenv usage with dynamic paths
feat(src/commands/config.ts): allow custom config and env paths in getConfig
refactor(src/commands/config.ts): streamline environment variable access

feat(test/unit): add unit tests for config handling and utility functions

- Implement unit tests for `getConfig` function to ensure correct behavior
  in various scenarios including default values, global config, and local
  env file precedence.
- Add utility function `prepareFile` for creating temporary files during
  tests, facilitating testing of file-based configurations.

* feat(e2e.yml): add unit-test job to GitHub Actions for running unit tests on pull requests

* ci(test.yml): add GitHub Actions workflow for unit and e2e tests on pull requests

* refactor(config.ts): streamline environment variable access using process.env directly
test(config.test.ts): add setup and teardown for environment variables in tests to ensure test isolation

* feat(package.json): add `test:all` script to run all tests in Docker
refactor(package.json): consolidate Docker build steps into `test:docker-build` script for DRY principle
fix(package.json): ensure `test:unit:docker` and `test:e2e:docker` scripts use the same Docker image and remove container after run
chore(test/Dockerfile): remove default CMD to allow dynamic test script execution in Docker

* refactor(config.test.ts): anonymize API keys in tests for better security practices

* feat(config.test.ts): add tests for OCO_ANTHROPIC_API_KEY configuration

* refactor(config.ts): streamline path imports and remove unused DotenvParseOutput

- Simplify path module imports by removing default import and using named imports for `pathJoin` and `pathResolve`.
- Remove unused `DotenvParseOutput` import to clean up the code.

* refactor(config.test.ts): simplify API key mock values for clarity in tests

* test(config.test.ts): remove tests for default config values and redundant cases

- Removed tests that checked for default config values when no config or env files are present, as these scenarios are now handled differently.
- Eliminated tests for empty global config and local env files to streamline testing focus on actual config loading logic.
- Removed test for prioritizing local env over global config due to changes in config loading strategy, simplifying the configuration management.

jest.config.ts

@@ -11,15 +11,17 @@ const config: Config = {
     "node_modules",
     "src",
   ],
-  preset: 'ts-jest',
+  preset: 'ts-jest/presets/js-with-ts-esm',
   setupFilesAfterEnv: ['<rootDir>/test/jest-setup.ts'],
   testEnvironment: "node",
   testRegex: [
     '.*\\.test\\.ts$',
   ],
+  transformIgnorePatterns: ['node_modules/(?!cli-testing-library)'],
   transform: {
     '^.+\\.(ts|tsx)$': ['ts-jest', {
       diagnostics: false,
+      useESM: true
     }],
   }
 };