It's easier to test individual items, for sure. Testing small code bases is the best thing ever. However, some actions require stuff to happen in multiple services.
There are "contracts" on how to talk to other services. You can test if you follow that contract, but it's hard to verify automatically that these contracts are in sync between apps.
There are "contracts" on how to talk to other services. You can test if you follow that contract, but it's hard to verify automatically that these contracts are in sync between apps.