Test utilities for plugins

Without test utilities, plugin authors must start the full host application and manually trigger hooks to verify their plugin's behavior. This makes the test cycle slow, fragile, and environment-dependent. Most plugin authors will skip testing entirely, producing a plugin ecosystem where bugs are discovered in production rather than in test suites. ISO 25010 maintainability.testability requires that components be verifiable in isolation; test utilities are the mechanism that makes plugin testability possible without running the full host stack.

Export a createTestHost() factory from the host package that creates an isolated test environment with mock context and hook invocation capabilities. This enables plugin authors to write fast, dependency-free unit tests.

// Exported from the host package:
export function createTestHost(options?: TestHostOptions): TestHost {
  return {
    register: (plugin) => { /* load plugin into isolated test env */ },
    invokeHook: (name, context) => { /* trigger hook and return results */ },
    getPluginState: (pluginName) => { /* inspect plugin's internal state */ },
  };
}

// Plugin author's test:
test('my plugin handles before:request', async () => {
  const host = createTestHost();
  await host.register(myPlugin);
  const result = await host.invokeHook('before:request', { url: '/test' });
  expect(result.modified).toBe(true);
});