[alkonaut]

I know. Which is why I have architectural tests that scream if someone uses the wrong module from the wrong place (adds a dependency that isn't what we want).

Of course, any dev could just remove the test, and by that tear down that boundary too. But that test being removed is much more obvious to the code reviewer who would not have noticed the dependency being snuck in. The architectural tests can also contain comments that form a high level documentation of the architecture. Unlike "architectural documents" in the form of some up front word document, this type tends to stay up to date.

[cerved]

interesting, how do you implement such a test?

[alkonaut]

In .NET I do it om the binaries, I reflect over the assemblies and list the dependencies.

In the same run one can also validate that there are no incompatible transitive dependencies.

Within assemblies (between namespaces) is much harder unfortunately. That means assemblies have to be made to make module boundaries obvious, even though it’s a bit of an antipattern. There are tools such as nsdepcop that watch namespace dependencies, but it’s brittle and a lot of work.