Prevent double validations on save/save! (#70)

* Prevent double validations on save/save!

Originally, calling `form.save/!` would cause model validations to fire
off twice.

The first time when the form's validations are being run (as the form
has a validation to ensure that all `models` are valid`)

The second time is when the `models` are looped over and they each
receive `save!`.

For validations that are done with in-memory data, such as `validate
:attribute, presence: true`, this isn't a big deal. But this could be
problematic for any validation that is dependent on the state of the
database (it will effectively hit the database twice).

This instead passes `validate: false` into the saving of models so that
their validations aren't run a second time.

* Update README to reflect line count

README.md

@@ -50,7 +50,7 @@ If you want to learn more about Form Objects you can check out [these great arti
 
 ### Why YAAF?
 
-- It is [69 lines long](https://github.com/rootstrap/yaaf/blob/master/lib/yaaf/form.rb#L69). As you can imagine, we did no magic in such a few lines of code, we just leveraged Rails modules in order to provide our form objects with a Rails-like behavior. You can review the code, it's easy to understand.
+- It is [71 lines long](https://github.com/rootstrap/yaaf/blob/master/lib/yaaf/form.rb#L71). As you can imagine, we did no magic in such a few lines of code, we just leveraged Rails modules in order to provide our form objects with a Rails-like behavior. You can review the code, it's easy to understand.
 
 - It provides a similar API to `ActiveModel` models so you can treat them interchangeably.
 

lib/yaaf/form.rb

@@ -50,6 +50,8 @@ def save_in_transaction(options)
     end
 
     def save_models(options)
+      options.merge!(validate: false)
+
       models.map { |model| model.save!(options) }
     end
 

spec/support/models/user.rb

@@ -1,3 +1,9 @@
 class User < ActiveRecord::Base
   validates :name, presence: true
+
+  validate :custom_validation
+
+  def custom_validation
+    'A validation method used in the specs'
+  end
 end

spec/yaaf/model_validations_spec.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+RSpec.describe 'Model validations' do
+  let(:form) { WithValidationCallbacksForm.new(args) }
+  let(:email) { 'test@example.com' }
+  let(:name) { 'John' }
+  let(:args) do
+    { email: email, name: name, before_counter: 0, after_counter: 0 }
+  end
+
+  context 'by default' do
+    let(:options) { {} }
+
+    %i[save save!].each do |persistence_method|
+      it "calling #{persistence_method} runs the model validations only once" do
+        expect(form.user).to receive(:custom_validation).once
+
+        form.send(persistence_method, options)
+      end
+    end
+  end
+
+  context 'with validate: false' do
+    let(:options) { { validate: false } }
+
+    %i[save save!].each do |persistence_method|
+      it "calling #{persistence_method} doesn't run model validations" do
+        expect(form.user).not_to receive(:custom_validation)
+
+        form.send(persistence_method, options)
+      end
+    end
+  end
+end