interested in your thoughts on a potential pattern there are

Question

interested in your thoughts on a potential pattern there are a few different target types which should be treated as root only on the JVM such that we should fail at compile time or preferably earlier if a dependee requests a classpath for them examples 1 `deploy jar` 2 ` scala junit tests` 3 any other root target

witty-crayon-22786 · Answer

i m thinking of adding a union that would declare these types such that they can legally be used as the root of a request for a classpath but fail when used as an inner node although that might be too strict for tests since it s likely that folks have test targets depending on other test targets despite that being questionable

hundreds-father-404 · Answer

gt since it s likely that folks have test targets depending on other test targets despite that being questionable Is it This is a huge reason I felt so strongly about <https github com pantsbuild pants issues 13238> for Python land Although in Python it is legal for a test to import another test

witty-crayon-22786 · Answer

i m wondering whether to have the union include a particular `Field` on the targets or the `Target` type itself

hundreds-father-404 · Answer

The Target API is meant to be field driven so that we re robust to users writing custom target types So you could use a private sentinel field as a marker I started to move away from a field driven API with target generation being based on the target itself but I m still not 100 convinced that was the right approach

witty-crayon-22786 · Answer

gt Is it it might be alright if the testrunner is carefully configured to only run the root tests rather than all tests on the path but otherwise it leads to tests running multiple times once for each test target that depends on them it s also never a good idea for library prod code to depend on tests and no dependees defends against that as well

witty-crayon-22786 · Answer

< hundreds father 404> right now the `resolve` field is a really obvious marker but i do think that we re going to want to replace it with `compatible resolves` for consistency

hundreds-father-404 · Answer

Right I agree it s not a good idea for tests to depend on tests I m questioning if people actually are doing that in the wild

witty-crayon-22786 · Answer

gt I m questioning if people actually are doing that in the wild in a random tailored repo probably but perhaps not

hundreds-father-404 · Answer

To be clear are you thinking of inferred dependencies between tests That regardless of Pants you have Java test code that imports another test file

witty-crayon-22786 · Answer

< hundreds father 404> i guess that i could just pick some other random field which is distinct for each of these targets to put in the union

witty-crayon-22786 · Answer

gt To be clear are you thinking of inferred dependencies between tests That regardless of Pants you have Java test code that imports another test file right especially since it is file level

witty-crayon-22786 · Answer

not super common but possible easy to do in Python easy to do in Scala little bit harder in Java

hundreds-father-404 · Answer

Got it I can t comment to how frequently that happens in JVM not enough experience But I do know it s legal and does happen in Python