Tests and elm-format overwriting the exposing list

I got caught out by elm-format changing the exposing list in my test module. It changed exposing (..) to exposing (suite), so when I added another suite, suite2 : Test, with a failing test, and forgot to update the exposing list manually, elm-test still reported that the tests passed – incorrectly – because the new failing test wasn’t included in the test run.

In this situation, code formatting is potentially affecting reliability of the code, and it seems that exposing (..) would be a more reliable option. I’m not sure if there is even a use case for non-exposed Test values given that elm-test provides skip and only for running subsets of tests.

To work around this, I could either put all the tests into a single Test value, nesting liberally with describe, or I could have a rule to define one Test value per file, splitting tests across multiple files.

I’m interested to know whether other people have run into this issue, and if you did, how do you manage the tests? Is it really unusual to define multiple Test values in a single file?

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I think ultimately the solution here is for the compiler to warn about unused definitions. A top-level definition would be unused if it is not referenced within the module and also not exported. That would have caught your problem.

The exellent elm-analyse performed this check, but is unfortunately not yet updated for 0.19.

Unfortunately neither of these gives you any help now.


I think the answer, for now, is just “you need to remember to manually add tests to the exposing list”. Maybe elm-format shouldn’t overwrite exposing (..).

Like @allanderek said, I’d love to see an “unused variable” warning. I’ve found that would catch a large percentage of the errors I see these days (considering the type system does such a great job!). Since Elm is a pure language, defining and not using a variable can’t do anything except eat up a bit of processing power so I’d venture to say an unused variable is always a mistake or oversight. (Side note: the special underscore variable _ would not be considered unused).


Another possible solution would be for elm-format to only override the exposing list in packages, which I’ve seen somebody suggest. (I guess even in packages, it would still be necessary to exclude test modules somehow).

I just don’t see the use case for not exporting Test values, and hence for maintaining a long exposing list in every test module.


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