CFN Synthesis Tests

These tests verify that serverless-appsync-plugin generates the expected CloudFormation when applied to a variety of real-world configurations. They complement the unit tests in src/__tests__/:

Concern	Unit tests	CFN synthesis tests
Pure function logic	✓
Schema validation	✓
Type coercion	✓
Plugin lifecycle on a real serverless.yml		✓
Generated CloudFormation resources	partial (snapshots)	✓
Feature combinations		✓
Example projects stay current with the plugin		✓

How it works

Each test loads one of the example projects under ../examples/, runs serverless package to produce a CloudFormation template, and asserts on the generated resources.

Critically, these tests do not deploy anything to AWS — they only exercise the synthesis path. That makes them fast (~3s per fixture), fork-safe (no AWS credentials required), and suitable to run on every PR.

Running locally

# Run all CFN synthesis tests
npm run test:e2e

# Run everything (unit + synthesis)
npm run test:all

# Run a single fixture
npx jest --config jest.e2e.config.ts basic-api-key

Adding a new test

1. Create a new example under examples/<feature>/:
   • serverless.yml — minimal configuration demonstrating the feature
   • schema.graphql — GraphQL schema (or multiple .graphql files)
   • Any handlers or resolver code the example needs
2. Add an entry to ../examples/README.md
3. Create e2e/<feature>.e2e.test.ts using the helpers from helpers/
4. Run npm run test:e2e to verify

The example should be runnable: a user should be able to cd into it, run serverless deploy (with AWS credentials), and get a working AppSync API. That keeps the examples honest as documentation.

Helpers reference

See helpers/synthesize.ts and helpers/assertions.ts for the full set of utilities. The common patterns:

import { synthesize } from './helpers/synthesize';
import {
  expectAuthenticationType,
  expectDataSourceOfType,
  expectResourceWithProperties,
  findOneResourceByType,
  getGraphQlApi,
} from './helpers/assertions';

describe('examples/my-feature', () => {
  let result: ReturnType<typeof synthesize>;

  beforeAll(() => {
    result = synthesize('examples/my-feature');
  });

  afterAll(() => {
    result.cleanup();
  });

  it('does the thing', () => {
    expectAuthenticationType(result.template, 'API_KEY');
  });
});

CI

A dedicated e2e job in .github/workflows/ci.yml runs the full synthesis test suite on every PR and push to master or alpha. It runs after the unit-test matrix completes successfully (no point running E2E if unit tests already failed).