# Running tests for elm/core

**URL:** <https://discourse.elm-lang.org/t/running-tests-for-elm-core/3073>\
**Category:** Learn\
**Created:** [February 1, 2019, 2:32am UTC](https://discourse.elm-lang.org/t/running-tests-for-elm-core/3073 "2019-02-01T02:32:21Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![jerith](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.elm-lang.org/jerith/32/114_2.png) [@jerith](https://discourse.elm-lang.org/u/jerith)\
**Post date:** [February 1, 2019, 2:32am UTC](https://discourse.elm-lang.org/t/running-tests-for-elm-core/3073/1 "2019-02-01T02:32:21Z")

</div>

I’m hoping to work on a fix for [this `elm/core` bug](https://github.com/elm/core/issues/1011).

Seems like the right place to start is to run the existing test suite. Running `elm-test` produced some errors, though.

The first couple were easy to fix; I made these changes on top of the current tip of its master branch ([`22b2d7a2`](https://github.com/elm/core/commit/22b2d7a235003a88af4e4af58c3d0edf43684bc9)):

```
diff --git a/elm.json b/elm.json
index 745d790..1d9f9cc 100644
--- a/elm.json
+++ b/elm.json
@@ -35,5 +35,7 @@
     },
     "elm-version": "0.19.0 <= v < 0.20.0",
     "dependencies": {},
- "test-dependencies": {}
-}
\ No newline at end of file
+ "test-dependencies": {
+ "elm-explorations/test": "1.2.1 <= v < 2.0.0"
+ }
+}
diff --git a/tests/Test/List.elm b/tests/Test/List.elm
index ed26f0f..d5fd9d2 100644
--- a/tests/Test/List.elm
+++ b/tests/Test/List.elm
@@ -3,7 +3,7 @@ module Test.List exposing (tests)
 import Test exposing (..)
 import Expect
 import Basics exposing (..)
-import Maybe exposing (Maybe(Nothing, Just))
+import Maybe exposing (Maybe(..))
 import List exposing (..)

```

That gets me to this error, which has me stumped:

```
$ rm -rf .elm && ELM_HOME=$(pwd)/.elm ./node_modules/elm-test/bin/elm-test 
-- AMBIGUOUS IMPORT ------------- /home/matt/git/elm/core/tests/Test/Bitwise.elm

The Test.Bitwise module has an ambiguous import:

    import Bitwise

I found multiple module with that name though:

    /home/matt/git/elm/core/src/Bitwise.elm
    exposed by elm/core 1.0.0

Which is the right one? Try renaming your modules to have unique names.

Compilation failed while attempting to build /home/matt/git/elm/core/tests/Main.elm /home/matt/git/elm/core/tests/Test/Array.elm /home/matt/git/elm/core/tests/Test/Basics.elm /home/matt/git/elm/core/tests/Test/Bitwise.elm /home/matt/git/elm/core/tests/Test/Char.elm /home/matt/git/elm/core/tests/Test/CodeGen.elm /home/matt/git/elm/core/tests/Test/Dict.elm /home/matt/git/elm/core/tests/Test/Equality.elm /home/matt/git/elm/core/tests/Test/List.elm /home/matt/git/elm/core/tests/Test/Maybe.elm /home/matt/git/elm/core/tests/Test/Result.elm /home/matt/git/elm/core/tests/Test/Set.elm /home/matt/git/elm/core/tests/Test/String.elm /home/matt/git/elm/core/tests/Test/Tuple.elm

```

There is a [`tests/run-tests.sh` script](https://github.com/elm/core/blob/master/tests/run-tests.sh), but clearly it hasn’t been updated for 0.19 yet (it still references `elm-make` etc. and git history says it was last touched in 2016).

That `run-tests.sh` script seems like it’s trying to fake out the `elm/core` directory inside the old `elm-stuff/` directory. So I tried something similar based on my understanding of how the analogous mechanism works in 0.19:

```
$ rm -rf .elm/0.19.0/package/elm/core/1.0.0 && ln -s $(pwd) .elm/0.19.0/package/elm/core/1.0.0

$ ELM_HOME=$(pwd)/.elm ./node_modules/elm-test/bin/elm-test 
elm: getCurrentDirectory:getWorkingDirectory: does not exist (Current working directory no longer exists)
elm: getCurrentDirectory:getWorkingDirectory: does not exist (Current working directory no longer exists)
elm: getCurrentDirectory:getWorkingDirectory: does not exist (Current working directory no longer exists)
elm: getCurrentDirectory:getWorkingDirectory: does not exist (Current working directory no longer exists)
elm: thread blocked indefinitely in an MVar operation
Compilation failed while attempting to build /home/matt/git/elm/core/tests/Main.elm /home/matt/git/elm/core/tests/Test/Array.elm /home/matt/git/elm/core/tests/Test/Basics.elm /home/matt/git/elm/core/tests/Test/Bitwise.elm /home/matt/git/elm/core/tests/Test/Char.elm /home/matt/git/elm/core/tests/Test/CodeGen.elm /home/matt/git/elm/core/tests/Test/Dict.elm /home/matt/git/elm/core/tests/Test/Equality.elm /home/matt/git/elm/core/tests/Test/List.elm /home/matt/git/elm/core/tests/Test/Maybe.elm /home/matt/git/elm/core/tests/Test/Result.elm /home/matt/git/elm/core/tests/Test/Set.elm /home/matt/git/elm/core/tests/Test/String.elm /home/matt/git/elm/core/tests/Test/Tuple.elm

```

So, is there a way to run these tests?

---

<div class="post-metadata">

**Author:** ![jerith](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.elm-lang.org/jerith/32/114_2.png) [@jerith](https://discourse.elm-lang.org/u/jerith)\
**Post date:** [February 3, 2019, 3:38pm UTC](https://discourse.elm-lang.org/t/running-tests-for-elm-core/3073/2 "2019-02-03T15:38:23Z")

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I’ve gotten a tiny bit farther, by basically creating an entirely separate (empty) project with these tests. So they’ll be testing the `elm/core` that comes from `package.elm-lang.org` not from the local project.

(I think I can later get around that by running the tests under `nix` where I can insert local copies of the `elm/core` source into `$ELM_HOME`.)

Anyway, doing this indicates that these tests have clearly not been updated from 0.18 to 0.19 syntax. I think I’m going to start on that work, but it’s obviously kind of a big task, so I don’t want to repeat work if it’s already been done elsewhere. Anybody know if has?

---

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**Author:** ![mfeineis](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.elm-lang.org/mfeineis/32/104_2.png) [@mfeineis](https://discourse.elm-lang.org/u/mfeineis)\
**Post date:** [February 4, 2019, 7:51pm UTC](https://discourse.elm-lang.org/t/running-tests-for-elm-core/3073/3 "2019-02-04T19:51:45Z")

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The last time I heard something about tests for the core stuff - including the compiler - was that they were not found useful enough to have them. I personally don’t agree with that notion, good tests are never a waste of time, especially regression tests. I too would be very interested in case anybody has more up-to-date information on that topic.

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<div class="post-metadata">

**Author:** ![jerith](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.elm-lang.org/jerith/32/114_2.png) [@jerith](https://discourse.elm-lang.org/u/jerith)\
**Post date:** [February 7, 2019, 4:07am UTC](https://discourse.elm-lang.org/t/running-tests-for-elm-core/3073/4 "2019-02-07T04:07:51Z")

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I’ve gotten the tests running over in [the `update-019` branch](https://github.com/jerith666/core/tree/update-019) in my fork of `elm-core`. However they’re testing the code from [package.elm-lang.org](http://package.elm-lang.org), not the code in the local git working copy.

This did reveal an interesting change from 0.18 to 0.19 that AFAIK isn’t documented anywhere: hex strings (e.g. “0xBEEF”) [no longer parse](https://github.com/jerith666/core/commit/231183ab3a64ffc5474b56edc822d711f408877a) with `String.toInt`.

I’ve also been able to build upon this to create [a test for the bug](https://github.com/jerith666/core/commit/025b8741dabed2a16121ebe685aa338b48be22fe) I’m interested in. So I’ll keep working on making these 0.19-compatible tests actually run against the local git working copy, so I can develop and verify a fix.

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<div class="post-metadata">

**Author:** ![jerith](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.elm-lang.org/jerith/32/114_2.png) [@jerith](https://discourse.elm-lang.org/u/jerith)\
**Post date:** [February 9, 2019, 7:04pm UTC](https://discourse.elm-lang.org/t/running-tests-for-elm-core/3073/5 "2019-02-09T19:04:38Z")

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> <https://github.com/elm/core/pull/1017>

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<div class="post-metadata">

**Author:** ![system](https://canada1.discourse-cdn.com/flex035/uploads/elm_lang/original/1X/50a05e53677a2c3b47776d7abd0f113eb50193a1.png) [@system](https://discourse.elm-lang.org/u/system)\
**Post date:** [February 19, 2019, 7:04pm UTC](https://discourse.elm-lang.org/t/running-tests-for-elm-core/3073/6 "2019-02-19T19:04:40Z")

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