For logic heavy parts of the system then yes, narrow tests are very useful. Often these sorts of components are amenable to property based testing which definitely becomes harder the broader the surface. I have generally been lucky that these bits of code are either rare, or they become infrastructure dependencies quite quickly in which case you’re broadly testing just categories of responses, not all edge cases.
But I still think a general rule to live by is to maximise the ratio of business value covered by tests to the amount of program text referenced by tests. Too small a ratio and you’re gaining little confidence but exposing yourself to constant toil just to keep up with changing implementations, even when observable system behaviour doesn’t change much.
I’m unsure if top level sociable tests get me where I want to be. It seems like they stop one layer down, so I’m still concerned I don’t capture actual end to end use cases anywhere in the codebase. I’m not personally comfortable with that (from a testing point of view but also because I’m tired of working on codebases that don’t clearly reveal what they do and why), but that outlook’s been formed by my own particular failures and shortcomings over the years so it might be quite subjective.
But I still think a general rule to live by is to maximise the ratio of business value covered by tests to the amount of program text referenced by tests. Too small a ratio and you’re gaining little confidence but exposing yourself to constant toil just to keep up with changing implementations, even when observable system behaviour doesn’t change much.
I’m unsure if top level sociable tests get me where I want to be. It seems like they stop one layer down, so I’m still concerned I don’t capture actual end to end use cases anywhere in the codebase. I’m not personally comfortable with that (from a testing point of view but also because I’m tired of working on codebases that don’t clearly reveal what they do and why), but that outlook’s been formed by my own particular failures and shortcomings over the years so it might be quite subjective.