Validating interim calls formed in Mono

Question

I have a class that returns a Mono type collection, something like this and I want to add a test that verifies the interim calls that mono goes through in chain: My method to test is in Test class

@Override
    public @NonNull Mono<Collection<Group>> getGroupsAsync(@NonNull String groupName,
                                                                        @NonNull String name) throws MyException {
        try {
            return inner.networkGroups().getByGroupAsync(groupName, name)
                    .filter(skipNullNsg(name, groupName))
                    .flatMap(nsg -> Mono.just(n.groups().values()));
        } catch (Exception ex) {
            throw MyException(ex);
                    
        }
    }

My test is:

@Test
    public void getGroups() throws MyException {
        
        assertNotNull(inner.networkGroups().getByGroupAsync(groupName, name).block());
       }

My question is how can I use the chain of mono to check the interim states as this is an async call.