Tests to print validation failure messages from changesets

Questions / Help
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#1

Hi, all!
I was wondering if there is any way to have ExUnit tests to print validation failure messages from changesets when it seeds the database.
I have this validate_inclusion changeset for a field, and I just spent an awful lot of time testing this one model completely oblivious of a typo I made in my seed script because I thought the message would pop up to me in test if the validation would fail.

I’m probably missing something fundamental on how either ExUnit or changesets work.

#2

What do you mean by seeding in this case?

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#3 
assert changeset.valid?
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#4

Did you use Repo.insert! or Repo.update! when using the changeset, or did you use Repo.insert or Repo.update. The ! versions of the functions will raise if the changeset fails, whereas the non ! versions will return {:ok, result} | {:error, error} tuples. If you want a noisy failure, use !.

2 Likes
#5

I guess the right term would be a fixture? I’m referring to a function I call with setup that seeds the database for each test!

Oh, this is a great tip… I completely missed that the return format of these functions are totally different. Thanks!

#6

Also… it might be a silly question, but writing code using the bang version is best practice or available mostly for troubleshooting?
Cause when I use it I get all sorts of CaseClauseError that I don’t even understand, but everything seems to work fine when I use the version without it. It makes me feel like I shouldn’t be leaving it like this haha :grimacing: