Testing Update

Testing Elixir — by Andrea Leopardi, Jeffrey Matthias (51 / 80)

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Testing update is a bit of a combination of the testing for the create and read functions. Let’s first look at the function we’re going to test:

testing_ecto/lib/users/users.ex

​ ​def​ update(%User{} = existing_user, update_params) ​do​
​   existing_user
​   |> User.update_changeset(update_params)
​   |> Repo.update()
​ ​end​

You can see that, like create/1, this function is a very lightweight wrapper around calls to the schema’s changeset function (update_changeset/2 in this case) and then to Repo.update/1. Testing it will be similar, but you’ll need to insert an existing user to be updated by the code. Let’s write our success test first:

​1: describe ​"​​update/2"​ ​do​
​-   test ​"​​success: it updates database and returns the user"​ ​do​
​-     existing_user = Factory.insert(​:user​) 
​- 
​5:     params =  
​-       Factory.string_params_for(​:user​)
​-       |> Map.take([​"​​first_name"​])
​- 
​-     assert {​:ok​, returned_user} = Users.update(existing_user, params)
​10: 
​-     user_from_db = Repo.get(User, returned_user.id)
​-     assert returned_user == user_from_db
​- 
​-     expected_user_data =  
​15:       existing_user
​-       |> Map.from_struct()
​-       |> Map.drop([​:__meta__​, ​:updated_at​])  
​-       |> Map.put(​:first_name​, params[​"​​first_name"​])
​- 
​20:     for {field, expected} <…