discourse/plugins/chat/spec/support/chat_service_matcher.rb
Martin Brennan 60ad836313
DEV: Chat service object initial implementation (#19814)
This is a combined work of Martin Brennan, Loïc Guitaut, and Joffrey Jaffeux.

---

This commit implements a base service object when working in chat. The documentation is available at https://discourse.github.io/discourse/chat/backend/Chat/Service.html

Generating documentation has been made as part of this commit with a bigger goal in mind of generally making it easier to dive into the chat project.

Working with services generally involves 3 parts:

- The service object itself, which is a series of steps where few of them are specialized (model, transaction, policy)

```ruby
class UpdateAge
  include Chat::Service::Base

  model :user, :fetch_user
  policy :can_see_user
  contract
  step :update_age

  class Contract
    attribute :age, :integer
  end

  def fetch_user(user_id:, **)
    User.find_by(id: user_id)
  end

  def can_see_user(guardian:, **)
    guardian.can_see_user(user)
  end

  def update_age(age:, **)
    user.update!(age: age)
  end
end
```

- The `with_service` controller helper, handling success and failure of the service within a service and making easy to return proper response to it from the controller

```ruby
def update
  with_service(UpdateAge) do
    on_success { render_serialized(result.user, BasicUserSerializer, root: "user") }
  end
end
```

- Rspec matchers and steps inspector, improving the dev experience while creating specs for a service

```ruby
RSpec.describe(UpdateAge) do
  subject(:result) do
    described_class.call(guardian: guardian, user_id: user.id, age: age)
  end

  fab!(:user) { Fabricate(:user) }
  fab!(:current_user) { Fabricate(:admin) }

  let(:guardian) { Guardian.new(current_user) }
  let(:age) { 1 }

   it { expect(user.reload.age).to eq(age) }
end
```

Note in case of unexpected failure in your spec, the output will give all the relevant information:

```
  1) UpdateAge when no channel_id is given is expected to fail to find a model named 'user'
     Failure/Error: it { is_expected.to fail_to_find_a_model(:user) }

       Expected model 'foo' (key: 'result.model.user') was not found in the result object.

       [1/4] [model] 'user' 
       [2/4] [policy] 'can_see_user'
       [3/4] [contract] 'default'
       [4/4] [step] 'update_age'

       /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/update_age.rb:32:in `fetch_user': missing keyword: :user_id (ArgumentError)
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:202:in `instance_exec'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:202:in `call'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:219:in `call'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:417:in `block in run!'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:417:in `each'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:417:in `run!'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:411:in `run'
       	from <internal:kernel>:90:in `tap'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/app/services/base.rb:302:in `call'
       	from /Users/joffreyjaffeux/Code/pr-discourse/plugins/chat/spec/services/update_age_spec.rb:15:in `block (3 levels) in <main>'
```
2023-02-13 13:09:57 +01:00

136 lines
2.7 KiB
Ruby

# frozen_string_literal: true
module Chat
module ServiceMatchers
class FailStep
attr_reader :name, :result
def initialize(name)
@name = name
end
def matches?(result)
@result = result
step_exists? && step_failed? && service_failed?
end
def failure_message
message =
if !step_exists?
"Expected #{type} '#{name}' (key: '#{step}') was not found in the result object."
elsif !step_failed?
"Expected #{type} '#{name}' (key: '#{step}') to fail but it succeeded."
else
"expected the service to fail but it succeeded."
end
error_message_with_inspection(message)
end
def failure_message_when_negated
message = "Expected #{type} '#{name}' (key: '#{step}') to succeed but it failed."
error_message_with_inspection(message)
end
private
def step_exists?
result[step].present?
end
def step_failed?
result[step].failure?
end
def service_failed?
result.failure?
end
def type
"step"
end
def error_message_with_inspection(message)
inspector = StepsInspector.new(result)
"#{message}\n\n#{inspector.inspect}\n\n#{inspector.error}"
end
end
class FailContract < FailStep
attr_reader :error_message
def step
"result.contract.#{name}"
end
def type
"contract"
end
def matches?(service)
super && has_error?
end
def has_error?
result[step].errors.present?
end
def failure_message
return "expected contract '#{step}' to have errors" unless has_error?
super
end
def description
"fail a contract named '#{name}'"
end
end
class FailPolicy < FailStep
def type
"policy"
end
def step
"result.policy.#{name}"
end
def description
"fail a policy named '#{name}'"
end
end
class FailToFindModel < FailStep
def type
"model"
end
def step
"result.model.#{name}"
end
def description
"fail to find a model named '#{name}'"
end
end
def fail_a_policy(name)
FailPolicy.new(name)
end
def fail_a_contract(name = "default")
FailContract.new(name)
end
def fail_to_find_a_model(name = "model")
FailToFindModel.new(name)
end
def inspect_steps(result)
inspector = Chat::StepsInspector.new(result)
puts "Steps:"
puts inspector.inspect
puts "\nFirst error:"
puts inspector.error
end
end
end