[apigateway] Throttling per method not set when value=0

[cyuste]

When we create a throttling for a method with rate and burst limits set to 0 we expect to have that method configured to allow 0 requests (disabled) as it happens using aws console, but in cdk the throttling is not configured causing the method to use global values

Reproduction Steps

Create an API Gateway and assign to an usage plan a throttling per method set to 0:

throttle = new APIGateway.ThrottleSettings
{
     RateLimit = 0,
     BurstLimit = 0
};

What did you expect to happen?

A new throttling per method is created for the specified method with rate and burst set to 0

What actually happened?

No throttling is configured for that method. In the cloudformation that throttling is described as:

"Throttle": {
  ...
  "/ServiceManager.svc/ANY": {},
}

It should contain BurstLimit and RateLimit set to 0.

Environment

• CLI Version : 1.60.0 (build 8e3f53a)
• Framework Version:
• Node.js Version: v14.7.0
• OS : Max OS X Catalina 10.15.6
• Language (Version): dotnet (3.1.301)

Other

I think that the problem is in this condition

As 0 is considered false an thus undefined

---

This is 🐛 Bug Report

[cyuste]

I downloaded aws-cdk repo and removed the conditional, i.e modify renderThrottle method and leave it as:

private renderThrottle(props: ThrottleSettings | undefined): (CfnUsagePlan.ThrottleSettingsProperty | Token) {
    let ret: CfnUsagePlan.ThrottleSettingsProperty | Token;
    if (props !== undefined) {
      const burstLimit = props.burstLimit;
      validateInteger(burstLimit, 'Throttle burst limit');
      const rateLimit = props.rateLimit;
      validateInteger(rateLimit, 'Throttle rate limit');

      ret = {
        burstLimit: burstLimit,
        rateLimit: rateLimit,
      };
    }
    return ret!;
  }

Unit tests pass and now the resultant cloudformation is correct. I can create a PR if needed. Any idea of why is that condition in the code? The values are already validated using validateInteger function...

[cyuste]

I created a branch with this change and a unit test that fails with the original version, it's my first PR so I left it as Draft

[nija-at]

This looks like the correct fix. Thanks @cyuste for creating a PR.
Move this out of draft state when you're ready so it can be reviewed and merged.

[cyuste]

PR ready for review :)