# Testing

When testing resources:
- Test your domain actions through the code interface
- Use test utilities in `Ash.Test`
- Test authorization policies work as expected using `Ash.can?`
- Use `authorize?: false` in tests where authorization is not the focus
- Write generators using `Ash.Generator`
- Prefer to use raising versions of functions whenever possible, as opposed to pattern matching

## Preventing Deadlocks in Concurrent Tests

When running tests concurrently, using fixed values for identity attributes can cause deadlock errors. Multiple tests attempting to create records with the same unique values will conflict.

### Use Globally Unique Values

Always use globally unique values for identity attributes in tests:

```elixir
# BAD - Can cause deadlocks in concurrent tests
%{email: "test@example.com", username: "testuser"}

# GOOD - Use globally unique values
%{
  email: "test-#{System.unique_integer([:positive])}@example.com",
  username: "user_#{System.unique_integer([:positive])}",
  slug: "post-#{System.unique_integer([:positive])}"
}
```

### Creating Reusable Test Generators

For better organization, create a generator module:

```elixir
defmodule MyApp.TestGenerators do
  use Ash.Generator

  def user(opts \\ []) do
    changeset_generator(
      User,
      :create,
      defaults: [
        email: "user-#{System.unique_integer([:positive])}@example.com",
        username: "user_#{System.unique_integer([:positive])}"
      ],
      overrides: opts
    )
  end
end

# In your tests
test "concurrent user creation" do
  users = MyApp.TestGenerators.generate_many(user(), 10)
  # Each user has unique identity attributes
end
```

This applies to ANY field used in identity constraints, not just primary keys. Using globally unique values prevents frustrating intermittent test failures in CI environments.