falsy reason in tests when using serverless AWSLambda.wrapHandler

[miladr0]

I'm writing tests for my lambda function but when I'm using @sentry/serverless and wrap my lambda function with AWSLambda.wrapHandler mocha shows Promise rejected with no or falsy reason.

Sample Lambda function:

const lambdaFn = async (event, context) => {
  context.callbackWaitsForEmptyEventLoop = false
  try {
    return  {
    200,
    body: JSON.stringify(body)
  }
  } catch (error) {
    console.error(error)
    sentry.captureException(error)
    await sentry.flush(2500)
  }
}

exports.actualLambda = lambdaFn
exports.handler = sentry.AWSLambda.wrapHandler(lambdaFn)

Sample test(not working as expected):

  it('status must be 200', async () => {
       const result = await app.handler(null, context)
       expect(result.statusCode).to.equal(200)
  })

But if I directly call exports.actualLambda function test will be passed. like below:
Sample test:

  it('status must be 200', async () => {
       const result = await app.actualLambda(null, context)
       expect(result.statusCode).to.equal(200)
  })

[G-Rath]

I hit upon a very similar issue that I suspect is the same - in my case, I was getting errors around it promises rejecting with just false.

The answer is that you have to call Sentry.init(); yourself - otherwise a client doesn't get initialized, which means flush will reject with false:

sentry-javascript/packages/node/src/sdk.ts

Lines 134 to 140 in ce40962

	export async function flush(timeout?: number): Promise<boolean> {
	const client = getCurrentHub().getClient<NodeClient>();
	if (client) {
	return client.flush(timeout);
	}
	return Promise.reject(false);
	}

IMO this is really bad, because it makes it almost impossible to know what the issue is without hunting around in the code, since there's no stack trace that'll point to this line.