Riff-Raff YAML generator doesn't always handle multiple instances of the same `GuStack`

[akash1810]

cc @richpryce

In https://github.com/guardian/datasync-notifier, we're instantiating the same GuStack class twice, to create two CloudFormation stacks. They differ only by the app property.

The Riff-Raff generator fails to correctly produce a file in this scenario:

  it("should create the correct riff-raff.yaml with multiple uses of the same class", () => {
    const app = new App({ outdir: "/tmp/cdk.out" });

    interface StackWithLambdaProps extends GuStackProps {
      app: string;
    }

    class StackWithLambda extends GuStack {
      // eslint-disable-next-line custom-rules/valid-constructors -- this is a test
      constructor(app: App, id: string, props: StackWithLambdaProps) {
        super(app, id, props);
        new GuLambdaFunction(this, "test", {
          app: props.app,
          runtime: Runtime.NODEJS_20_X,
          fileName: `${props.app}.zip`,
          handler: "handler.main",
          timeout: Duration.minutes(1),
        });
      }
    }

    new StackWithLambda(app, "test-stack-SYD", {
      stack: "test",
      stage: "TEST",
      app: "my-lambda-SYD",
      env: { region: "eu-west-1" },
    });

    new StackWithLambda(app, "test-stack-NYC", {
      stack: "test",
      stage: "TEST",
      app: "my-lambda-NYC",
      env: { region: "eu-west-1" },
    });

    const actual = new RiffRaffYamlFile(app).toYAML();
    expect(actual).toMatchSnapshot();
  });

This is because of how GuStacks are grouped; as the class name is the same, the generator thinks there is only one StackWithLambda.

A work-around is to sub-class:

class StackWithLambda extends GuStack {
  // eslint-disable-next-line custom-rules/valid-constructors -- this is a test
  constructor(app: App, id: string, props: StackWithLambdaProps) {
    super(app, id, props);
    new GuLambdaFunction(this, "test", {
      app: props.app,
      runtime: Runtime.NODEJS_20_X,
      fileName: `${props.app}.zip`,
      handler: "handler.main",
      timeout: Duration.minutes(1),
    });
  }
}

class StackOne extends StackWithLambda {}
class StackTwo extends StackWithLambda {}

Should there be better first-class support for this?