figured it out. expect was being imported from cdk assert.

import { expect, haveResource, SynthUtils } from '@aws-cdk/assert'

this is overwriting jests expect. Update expect from cdk to as expectCdk works.

import { expect as expectCDK, haveResource, SynthUtils } from '@aws-cdk/assert'

Oh yeah.. I ran into this too. Glad u figured it out.