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# Test Resources
```elixir
Mix.install([{:ash, "~> 3.0}, {:simple_sat, "~> 0.1"}],
consolidate_protocols: false
)
Logger.configure(level: :warning)
ExUnit.start()
```
## Introduction
We recommend testing your resources *thoroughly*. Often, folks think that testing an `Ash.Resource` is "testing the framework", and in some very simple cases this may be true, like a simple create that just accepts a few attributes.
However, testing has two primary roles:
1. Confirming our understanding of the way that our application behaves *now*
2. Ensuring that our application does not change in unintended ways *later*
To this end, we highly recommend writing tests even for your simple actions. A single test that confirms that, with simple inputs, the action returns what you expect, can be very powerful.
Additionally, Ash offers unique ways of testing individual components of our resources, similar to a unit test.
While you don't necessarily need to follow all steps below, we show the various ways you may want to go about testing your resources.
## Testing Resources
* Add tests for action inputs using property testing
* Add tests for calling action invocation using property testing
* Add explicit tests for action inputs/invocation using property testing.
* Add tests for our calculations
* Test policies "in isolation" using `Ash.can?` (or `Domain.can_*`, provided by code interfaces)
## Examples
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```elixir
defmodule User do
use Ash.Resource,
domain: Domain,
data_layer: Ash.DataLayer.Ets
actions do
defaults [:read, create: [:admin?]]
end
attributes do
uuid_primary_key :id
attribute :admin?, :boolean do
allow_nil? false
default false
end
end
end
defmodule Tweet do
use Ash.Resource,
domain: Domain,
data_layer: Ash.DataLayer.Ets,
authorizers: [Ash.Policy.Authorizer]
attributes do
uuid_primary_key :id
attribute :text, :string do
allow_nil? false
constraints max_length: 144
public? true
end
attribute :hidden?, :boolean do
allow_nil? false
default false
public? true
end
end
calculations do
calculate :tweet_length, :integer, expr(string_length(text))
end
relationships do
belongs_to :user, User, allow_nil?: false
end
actions do
defaults [:read, update: [:text]]
create :create do
primary? true
accept [:text]
change relate_actor(:user)
end
end
policies do
policy action_type(:read) do
description "If a tweet is hidden, only the author can read it. Otherwise, anyone can."
authorize_if relates_to_actor_via(:user)
forbid_if expr(hidden? == true)
authorize_if always()
end
policy action_type(:create) do
description "Anyone can create a tweet"
authorize_if always()
end
policy action_type(:update) do
description "Only an admin or the user who tweeted can edit their tweet"
authorize_if actor_attribute_equals(:admin?, true)
authorize_if relates_to_actor_via(:user)
end
end
end
defmodule Domain do
use Ash.Domain,
validate_config_inclusion?: false
resources do
resource Tweet do
define :create_tweet, action: :create, args: [:text]
define :update_tweet, action: :update, args: [:text]
define :list_tweets, action: :read
end
resource User do
define :create_user, action: :create
end
end
end
```
<!-- livebook:{"output":true} -->
```
{:module, Domain, <<70, 79, 82, 49, 0, 2, 46, ...>>,
[
Ash.Domain.Dsl.Resources.Resource,
Ash.Domain.Dsl.Resources.Options,
Ash.Domain.Dsl,
%{opts: [], entities: [...]},
Ash.Domain.Dsl,
Ash.Domain.Dsl.Resources.Options,
...
]}
```
## Write some tests
```elixir
defmodule ActionInvocationTest do
use ExUnit.Case
import ExUnitProperties
describe "valid inputs" do
# now if our action inputs are invalid when we think they should be valid, we will find out here
property "accepts all valid input" do
user = Domain.create_user!()
check all(input <- Ash.Generator.action_input(Tweet, :create)) do
{text, other_inputs} = Map.pop!(input, :text)
assert Domain.changeset_to_create_tweet(
text,
other_inputs,
authorize?: false,
actor: user
).valid?
end
end
# same as the above, but actually call the action. This tests the underlying action implementation
# not just intiail validation
property "succeeds on all valid input" do
user = Domain.create_user!()
check all(input <- Ash.Generator.action_input(Tweet, :create)) do
{text, other_inputs} = Map.pop!(input, :text)
Domain.create_tweet!(text, other_inputs, authorize?: false, actor: user)
end
end
test "can tweet some specific text, in addition to any other valid inputs" do
user = Domain.create_user!()
check all(
input <- Ash.Generator.action_input(Tweet, :create, %{text: "some specific text"})
) do
{text, other_inputs} = Map.pop!(input, :text)
Domain.create_tweet!(text, other_inputs, actor: user)
end
end
end
describe "authorization" do
test "allows a user to update their own tweet" do
user = Domain.create_user!()
tweet = Domain.create_tweet!("Hello world!", actor: user)
assert Domain.can_update_tweet?(user, tweet, "Goodbye world!")
end
test "does not allow a user to update someone elses tweet" do
user = Domain.create_user!()
user2 = Domain.create_user!()
tweet = Domain.create_tweet!("Hello world!", actor: user)
refute Domain.can_update_tweet?(user2, tweet, "Goodbye world!")
end
test "allows an admin user to update someone elses tweet" do
user = Domain.create_user!()
user2 = Domain.create_user!(%{admin?: true})
tweet = Domain.create_tweet!("Hello world!", actor: user)
assert Domain.can_update_tweet?(user2, tweet, "Goodbye world!")
end
end
describe "calculations" do
test "text length calculation computes the length of the text" do
user = Domain.create_user!()
tweet = Domain.create_tweet!("Hello world!", actor: user)
assert Ash.calculate!(tweet, :tweet_length) == 12
end
end
end
ExUnit.run()
```
<!-- livebook:{"output":true} -->
```
.......
Finished in 0.07 seconds (0.00s async, 0.07s sync)
2 properties, 5 tests, 0 failures
Randomized with seed 42546
```
<!-- livebook:{"output":true} -->
```
%{total: 7, failures: 0, skipped: 0, excluded: 0}
```
