elm-test fails to run when `elm-explorations/test` is in both the indirect dependencies and test-dependencies

[jfmengels]

Summary

elm-test fails to run when elm-explorations/test is in both the indirect dependencies (direct?) and test-dependencies.

SSCCE

# Create a new project
elm init
elm-test init
elm-test # Everything runs correctly
elm install jfmengels/elm-review
elm-test # RUN FAILURE

Here is the error message we get when running elm-test at the end:

-- ERROR IN DEPENDENCIES ---------------------------------------------- elm.json

It looks like the dependencies elm.json in were edited by hand (or by a 3rd
party tool) leaving them in an invalid state.

Try to change them back to what they were before! It is much more reliable to
add dependencies with elm install or the dependency management tool in
elm reactor.

Please ask for help on the community forums if you try those paths and are still
having problems!

Compilation failed while attempting to build /home/jeroen/dev/node-test-runner-deps-problem/tests/Example.elm

elm.json BEFORE installing jfmengels/elm-review

```json { "type": "application", "source-directories": [ "src" ], "elm-version": "0.19.1", "dependencies": { "direct": { "elm/browser": "1.0.2", "elm/core": "1.0.5", "elm/html": "1.0.0" }, "indirect": { "elm/json": "1.1.3", "elm/time": "1.0.0", "elm/url": "1.0.0", "elm/virtual-dom": "1.0.2" } }, "test-dependencies": { "direct": { "elm-explorations/test": "1.2.2" }, "indirect": { "elm/random": "1.0.0" } } } ```

elm.json AFTER installing jfmengels/elm-review

```json { "type": "application", "source-directories": [ "src" ], "elm-version": "0.19.1", "dependencies": { "direct": { "elm/browser": "1.0.2", "elm/core": "1.0.5", "elm/html": "1.0.0", "jfmengels/elm-review": "2.0.2" }, "indirect": { "elm/json": "1.1.3", "elm/parser": "1.1.0", "elm/project-metadata-utils": "1.0.1", "elm/random": "1.0.0", "elm/time": "1.0.0", "elm/url": "1.0.0", "elm/virtual-dom": "1.0.2", "elm-community/json-extra": "4.2.0", "elm-community/list-extra": "8.2.4", "elm-explorations/test": "1.2.2", "rtfeldman/elm-hex": "1.0.0", "rtfeldman/elm-iso8601-date-strings": "1.1.3", "stil4m/elm-syntax": "7.1.1", "stil4m/structured-writer": "1.0.2" } }, "test-dependencies": { "direct": { "elm-explorations/test": "1.2.2" }, "indirect": {} } } ```

Additional details

The problem is that elm-explorations/test is present both in the indrect dependencies and in the direct test-dependencies. It is added because jfmengels/elm-review depends on it, to provide tools to test the things you build with elm-review.

Manually removing elm-explorations/test from the indirect dependencies solves the problem, and lets elm-test run smoothly. Hence, when I run elm-review init which creates a very similar elm.json to the one above, the init subcommand manually removes it from the indirect dependencies. Without doing that, users of elm-review are not able to test what they built with elm-review.

This is IMO not a good solution, because whenever we install you install a dependency using elm install author/pkg, elm-explorations/test gets re-added to the indirect dependencies, re-introducing the issue. (I'm actually surprised the Elm compiler never complains about dependencies being manually edited).

I think the way node-test-runner manipulates the elm.json gets confused, and I would love this to be resolved, so that (at least) elm-review users can have a much nicer and surprise-less experience.

References

This issue was discussed over at elm-json: zwilias/elm-json#22

Additional notes

I have not tested whether elm-explorations/test being in the direct dependencies causes similar problems, but I imagine that it could.

Also, this problem might happen for other packages than elm-explorations/test being duplicated. I could imagine avh4/elm-program-test being in the indirect dependencies for a project and in the direct test-dependencies for instance.

Thanks

Thanks a lot for all the work you put into this tool, it is a pleasure to use it ❤️

[harrysarson]

I think the solution is to use elm-json to do proper test dependency resolution. @jfmengels maybe you could weigh in at #356 .

[jfmengels]

As @zwilias told me on Slack, elm-json is really slow offline (does it even work offline?) at the moment, so I don't think it is ready to be used in this project yet.

From using it in elm-review, I guess it could be much faster from using the "take what is available on file system".

I don't know how complex solving this particular bug would be, but I imagine it could be worth fixing it before elm-json gets ready. I'll try and take a look and see if I can make a PR.

@zwilias what do you think?

[harrysarson]

Makes sense 👍 If you do think about a PR, be warned that the dependancy solving code in this repository is very rough and ready.

[lydell]

I tried this on master and the error is no longer there! Must have been fixed by switching to elm-json in #451.

[harrysarson]

Fantastic