Testing UpdateQueries in Mutation to check if cache updates properly

[n0ahz]

I have a mutation which I can test using the ApolloTestingController. The expectOne and flushData is working properly.
However I have an updateQueries option defined in the mutation, which updates the cache.
This code is unreachable with the test code.
I tried setting up mock cache, by using provider APOLLO_TESTING_CACHE. But the code which updates the cache is never reached via spec test.
Can someone kindly assist me to get to the right direction? TIA