(@aws-cdk/assert): Unable to pass test if a resource doesn't exist

[longtv2222]

❓ General Issue

The Question

I want to write validation tests and make it a library so that every stack can follow best security practices, naming convention, ... for my cdk stacks.

I've been looking at aws-assert for it and it seems not possible to run test only if a resource exists in the stack.

For example, if I were to write:

import { haveResourceLike,expect } from "@aws-cdk/assert";
import { mystack } from "..."

test('Bucket versioning must be enabled', () => {
        expect(mystack).to(haveResourceLike("AWS::S3::Bucket", {
            VersioningConfiguration: {
                Status: "Enabled"
            }
        }));
})

without any bucket in the stack then that would fail as expected.

The issue #12452 had similar problem as mine and I tried the proposed solution which was

import { haveResourceLike,expect } from "@aws-cdk/assert";
import { mystack } from "..."

test('Bucket versioning must be enabled', () => {
    if (haveResourceLike("AWS::S3::Bucket"))
        expect(mystack).to(haveResourceLike("AWS::S3::Bucket", {
            VersioningConfiguration: {
                Status: "Enabled"
            }
        }));
})

However, the test didn't pass.

Is there anyway to bypass this limitation?

Environment

• CDK CLI Version: 1.109
• Module Version: 1.109.0
• Node.js Version: v12.18.3
• OS: Windows 10
• Language (Version): TypeScript (4.3.3)

Other information

[peterwoodworth]

Hey @longtv2222, I think in theory what you posted should work, can you tell me what specifically is going wrong when the test doesn't pass?

[longtv2222]

I created a sample repo for this https://github.com/longtv2222/cdk-assert-error. (Created with cdk init sample-app --language typescript)

It seems to me that the if statement didn't verify the existence of Queue.

[longtv2222]

For sanity check, I tried

import { expect as expectCDK, haveResourceLike } from '@aws-cdk/assert';
import * as cdk from '@aws-cdk/core';
import * as CdkAssertError from '../lib/cdk-assert-error-stack';

test('SQS Queue Exist', () => {
  const app = new cdk.App();
  // WHEN
  const stack = new CdkAssertError.CdkAssertErrorStack(app, 'MyTestStack');
  // THEN

  if (!haveResourceLike("AWS::SQS::Queue")) //Test if the if statement does anything
    expectCDK(stack).to(haveResourceLike("AWS::SQS::Queue", {
      VisibilityTimeout: 300
    }));
});

with

import * as sqs from '@aws-cdk/aws-sqs';
import * as cdk from '@aws-cdk/core';

export class CdkAssertErrorStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const queue = new sqs.Queue(this, 'CdkAssertErrorQueue', {
      visibilityTimeout: cdk.Duration.seconds(200)  //Different timeout value
    });
    
  }
}

However the test passed

[peterwoodworth]

Hmm I'm finding the same thing as you. The if statement isn't working, I'll research this and get back to you

[longtv2222]

For anyone who encounters this problem, my work around is to wrap haveResourceLike inside a try catch to check if a resource exists or not.
Sample code is as below:

import { expect as expectCDK, haveResourceLike } from '@aws-cdk/assert';
import * as cdk from '@aws-cdk/core';
import * as CdkAssertError from '../lib/cdk-assert-error-stack';

test('SQS Queue Exist', () => {
  const app = new cdk.App();
  // WHEN
  const stack = new CdkAssertError.CdkAssertErrorStack(app, 'MyTestStack');
  // THEN

  let sqsExist = true;
  try {
    expectCDK(stack).to(haveResourceLike("AWS::SQS::Queue"));
  } catch (error) {
    sqsExist = false; //SQS doesn't exist if haveResourceLike throws an error
  }

  if (sqsExist) {
    expectCDK(stack).to(haveResourceLike("AWS::SQS::Queue", {
      VisibilityTimeout: 300
    }));
  } else {
    console.warn('Resource does not exist but we pass them anyway');
  }
});

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