[part9] Compilation error when run 'elm test'

Hi, thanks for this workshop.

I have some issues to run tests on part 9

cd part9
elm package install -y && (cd tests && elm package install -y)
elm test

-- NAMING ERROR - /Users/trapcodien/trap/elm/elm-workshop/part9/tests/HtmlRunner.elm

Cannot find type `Model`

14| main : Program Never Model Msg
                         ^^^^^

-- NAMING ERROR - /Users/trapcodien/trap/elm/elm-workshop/part9/tests/HtmlRunner.elm

Cannot find type `Msg`

14| main : Program Never Model Msg
                               ^^^

Detected errors in 1 module.
Compilation failed while attempting to build /Users/trapcodien/trap/elm/elm-workshop/part9/tests/Auth.elm /Users/trapcodien/trap/elm/elm-workshop/part9/tests/HtmlRunner.elm /Users/trapcodien/trap/elm/elm-workshop/part9/tests/Main.elm /Users/trapcodien/trap/elm/elm-workshop/part9/tests/Tests.elm

I tried to delete tests/HtmlRunner.elm file, then i have this error :

Success! Compiled 1 module.
Successfully generated /dev/null
I cannot find module 'Test.Runner.Failure'.

Module 'Test.Reporter.Console.Format' is trying to import it.

Potential problems could be:
  * Misspelled the module name
  * Need to add a source directory or new dependency to elm-package.json
Compilation failed for /Users/trapcodien/trap/elm/elm-workshop/part9/elm-stuff/generated-code/elm-community/elm-test/src/Test/Generated/Main3385995764.elm

Did i miss something ?

rtfeldman / elm-workshop

[part9] Compilation error when run 'elm test' #21