Implement Create operation

.rspec

@@ -1,3 +1,3 @@
---format documentation
+--format progress
 --color
 --require spec_helper

doc/04-the-create-operation.md

@@ -23,28 +23,4 @@ module API
 end
 ```
 
-## Overriding defaults
-
-You can override the default model class (computed from the operation's namespace) by overriding the
-`#build_record` method:
-
-```ruby
-module API
-  module V1
-    module Post
-      module Operation
-        module Create < Pragma::Operation::Create
-          private
-
-          def build_record
-            ::Post.new
-          end
-        end
-      end
-    end
-  end
-end
-```
-
-To override the policy, contract and decorator you can call the usual `#policy`, `#contract` and
-`#decorator`.
+To override the defaults of this operation, have a look at the [source code](https://github.com/pragmarb/pragma/blob/master/lib/pragma/operation/index.rb).

lib/pragma.rb

@@ -12,6 +12,7 @@
 require 'pragma/operation/defaults'
 require 'pragma/operation/index'
 require 'pragma/operation/show'
+require 'pragma/operation/create'
 require 'pragma/operation/update'
 
 # A pragmatic architecture for building JSON APIs.

lib/pragma/operation/create.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+module Pragma
+  module Operation
+    # Finds the requested record, authorizes it, updates it accordingly to the parameters and
+    # responds with the decorated record.
+    #
+    # @author Alessandro Desantis
+    class Create < Pragma::Operation::Base
+      include Pragma::Operation::Defaults
+
+      def call
+        record = build_record
+        contract = build_contract(record)
+
+        validate! contract
+        authorize! contract
+
+        contract.save
+
+        respond_with resource: decorate(record)
+      end
+
+      protected
+
+      # Builds the requested record.
+      #
+      # @return [Object]
+      def build_record
+        self.class.model_klass.new
+      end
+    end
+  end
+end

spec/pragma/operation/create_spec.rb

@@ -0,0 +1,108 @@
+# frozen_string_literal: true
+RSpec.describe Pragma::Operation::Create do
+  subject(:context) do
+    operation_klass.call(
+      current_user: current_user,
+      params: params
+    )
+  end
+
+  let(:params) do
+    {
+      author_id: 1,
+      title: 'My Post'
+    }
+  end
+
+  let(:contract_klass) do
+    Class.new(Pragma::Contract::Base) do
+      property :author_id
+      property :title
+
+      validation do
+        required(:title).filled
+      end
+    end
+  end
+
+  let(:operation_klass) do
+    Class.new(described_class) do
+      def build_record
+        OpenStruct.new
+      end
+    end.tap do |klass|
+      klass.send(:contract, contract_klass)
+      allow(klass).to receive(:name).and_return('API::V1::Post::Operation::Create')
+    end
+  end
+
+  let(:current_user) { nil }
+
+  it 'creates the record' do
+    expect(context.resource.to_h).to eq(
+      title: 'My Post',
+      author_id: 1
+    )
+  end
+
+  context 'when invalid parameters are supplied' do
+    let(:params) do
+      {
+        author_id: 1,
+        title: ''
+      }
+    end
+
+    it 'responds with 422 Unprocessable Entity' do
+      expect(context.status).to eq(:unprocessable_entity)
+    end
+  end
+
+  context 'when a decorator is defined' do
+    let(:decorator_klass) do
+      Class.new(Pragma::Decorator::Base) do
+        property :title
+      end
+    end
+
+    before do
+      operation_klass.send(:decorator, decorator_klass)
+    end
+
+    it 'decorates the updated resource' do
+      expect(context.resource.to_hash).to eq(
+        'title' => 'My Post'
+      )
+    end
+  end
+
+  context 'when a policy is defined' do
+    let(:policy_klass) do
+      Class.new(Pragma::Policy::Base) do
+        def create?
+          resource.author_id == user.id
+        end
+      end
+    end
+
+    before do
+      operation_klass.send(:policy, policy_klass)
+    end
+
+    context 'when the user is authorized' do
+      let(:current_user) { OpenStruct.new(id: 1) }
+
+      it 'permits the creation' do
+        expect(context.resource.to_h).to eq(title: 'My Post', author_id: 1)
+      end
+    end
+
+    context 'when the user is not authorized' do
+      let(:current_user) { OpenStruct.new(id: 2) }
+
+      it 'does not permit the creation' do
+        expect(context.status).to eq(:forbidden)
+      end
+    end
+  end
+end

spec/pragma/operation/index_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 RSpec.describe Pragma::Operation::Index do
-  let(:context) { operation_klass.call(input_context) }
+  subject(:context) { operation_klass.call(input_context) }
 
   let(:operation_klass) do
     Class.new(described_class) do

spec/pragma/operation/show_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 RSpec.describe Pragma::Operation::Show do
-  let(:context) do
+  subject(:context) do
     operation_klass.call(
       current_user: current_user,
       params: { id: 1 }
@@ -68,7 +68,7 @@ def show?
       end
     end
 
-    context 'when the user is authorized' do
+    context 'when the user is not authorized' do
       let(:current_user) { OpenStruct.new(id: 2) }
 
       it 'does not permit the retrievla' do

spec/pragma/operation/update_spec.rb

@@ -1,12 +1,19 @@
 # frozen_string_literal: true
 RSpec.describe Pragma::Operation::Update do
-  let(:context) do
+  subject(:context) do
     operation_klass.call(
       current_user: current_user,
-      params: { id: 1, title: 'New Title' }
+      params: params
     )
   end
 
+  let(:params) do
+    {
+      id: 1,
+      title: 'New Title'
+    }
+  end
+
   let(:contract_klass) do
     Class.new(Pragma::Contract::Base) do
       property :author_id
@@ -41,6 +48,19 @@ def find_record
     )
   end
 
+  context 'when invalid parameters are supplied' do
+    let(:params) do
+      {
+        author_id: 1,
+        title: ''
+      }
+    end
+
+    it 'responds with 422 Unprocessable Entity' do
+      expect(context.status).to eq(:unprocessable_entity)
+    end
+  end
+
   context 'when a decorator is defined' do
     let(:decorator_klass) do
       Class.new(Pragma::Decorator::Base) do
@@ -80,7 +100,7 @@ def update?
       end
     end
 
-    context 'when the user is authorized' do
+    context 'when the user is not authorized' do
       let(:current_user) { OpenStruct.new(id: 2) }
 
       it 'does not permit the update' do