Gracefully handle Debug.crash about node-test-runner HOT 8 CLOSED

Update: this is fixed on a branch; will be included with the next release!

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Seems to be an issue with elm-make, added some details at https://github.com/opsb/elm-test-crash#elm-make-scenarios

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+1
I spent some quality time identifying this one today.

module Tests exposing (..)

import Test exposing (..)
import Expect
import String

crashingFunction = "blah" |> Debug.crash

all : Test
all =
    describe "A Test Suite"
        [ test "This will crash" <|
            \() ->
                Expect.equal crashingFunction "blah"
        ]

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@sjfloat nice work isolating that!

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Sure. At least I know what to suspect now if I get that behavior in a test.

Thanks for discovering it in the first place!

ᐧ

On Thu, Sep 22, 2016 at 9:56 AM, Oliver Searle-Barnes <
[email protected]> wrote:

@sjfloat https://github.com/sjfloat nice work isolating that!

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"I have delusions of grandeur. I believe myself to be Steve Jones"

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As a workaround, you can explicitly put a Debug.log as well as a Debug.crash, in which case it gets displayed in the elm-test output. For example, this is a function I often use in my tests:

unsafeDecodeString : Decoder a -> String -> a
unsafeDecodeString decoder json =
  let
    result =
      JD.decodeString decoder json
  in
  case result of
    Ok r ->
      r

    Err str ->
      str
        |> Debug.log "unsafeDecodeString"
        |> Debug.crash "unsafeDecodeString"

This will give output like:

success! Compiled 4 modules.
Successfully generated /var/folders/26/cpffj2js733d5kmk6m9w0n840000gn/T/elm_test_1161030-50093-jeoo8k.1g33c2qpvi.js
unsafeDecodeString: "Expecting an object with a field named `id` but instead got: {\"hello\":\"Dave\"}"

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I have used Debug.log in a fuzztest to sample the data to see if it is generating the data I want

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Just want to note that this is on my radar, and the plan is for any exception in a test to result in a failure with a message reporting the exception. It's nontrivial to implement but definitely doable.

(Adding something like Expect.crashes : (a -> b) -> Expectation also seems doable, but I'd want to consider that separately as a feature.)

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