Testing Delete

Testing Elixir — by Andrea Leopardi, Jeffrey Matthias (52 / 80)

👈 Testing Update | TOC | Wrapping Up 👉

Our last function, delete/1, is simple to test, as the code is a straight pass-through to Repo.delete/1. Let’s look at the function:

testing_ecto/lib/users/users.ex

​   ​def​ delete(%User{} = user) ​do​
​     Repo.delete(user)
​   ​end​
​ ​end​

We’ll only test the success path for this function because errors are incredibly unlikely. Additionally, writing a test that can force an error on delete is complicated and requires restructuring our code solely for testing. In this case, the payoff isn’t there. When that’s the case, we typically let our applications crash instead of trying to handle every possible failure. Let’s write our final test and then review what it does:

​ describe ​"​​delete/1"​ ​do​
​   test ​"​​success: it deletes the user"​ ​do​
​     user = Factory.insert(​:user​)
​ 
​     assert {​:ok​, _deleted_user} = Users.delete(user)
​ 
​     refute Repo.get(User, user.id)
​   ​end​
​ ​end​

Our test sets up by inserting a user. It then exercises the delete/1 function, asserting that it returns a success tuple. The last line is an assertion that the data is no longer in the database. In our case, we aren’t even concerned about the return value, so we’re dropping it. The most important thing is to just make sure that you have that last check on the database.

👈 Testing Update | TOC | Wrapping Up 👉

Testing Elixir by Andrea Leopardi, Jeffrey Matthias can be purchased in other book formats directly from the Pragmatic Programmers. If you notice a code error or formatting mistake, please let us know here so that we can fix it.