comprehensive test coverage

When adding new functionality, configuration options, or plugins, always include corresponding tests that verify the feature works as expected. Tests should comprehensively cover all aspects of the functionality, including input/output validation, data transformations, and edge cases. Additionally, structure tests as focused, single-responsibility test cases rather than combining multiple concerns into one test.

For example, when adding a bearer token plugin to a client configuration:

// Bad: Adding plugin without tests
const client = createAuthClient({
  plugins: [bearerClient()], // No tests verify this works
});

// Good: Adding plugin with comprehensive tests
describe('Bearer Token Plugin', () => {
  test('should authenticate with bearer token', async () => {
    // Test the plugin functionality
  });
  
  test('should handle invalid bearer tokens', async () => {
    // Test error cases
  });
});

When testing data transformations, verify both the transformation process and the final output. For array-to-string conversions, test that ["medium", "large"] transforms to '["medium","large"]' during storage and back to the original array when retrieved.