Implement Scopes::Criteria.

lib/cuprum/collections.rb

@@ -15,6 +15,8 @@ module Collections
     autoload :Relation,     'cuprum/collections/relation'
     autoload :Repository,   'cuprum/collections/repository'
     autoload :Resource,     'cuprum/collections/resource'
+    autoload :Scope,        'cuprum/collections/scope'
+    autoload :Scopes,       'cuprum/collections/scopes'
 
     # @return [String] the absolute path to the gem directory.
     def self.gem_path

lib/cuprum/collections/rspec/contracts.rb

@@ -19,5 +19,7 @@ module Contracts
       'cuprum/collections/rspec/contracts/relation_contracts'
     autoload :RepositoryContracts,
       'cuprum/collections/rspec/contracts/repository_contracts'
+    autoload :Scopes,
+      'cuprum/collections/rspec/contracts/scopes'
   end
 end

lib/cuprum/collections/rspec/contracts/scope_contracts.rb

@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+require 'cuprum/collections/rspec/contracts'
+
+module Cuprum::Collections::RSpec::Contracts
+  # Contracts for asserting on scope objects.
+  module ScopeContracts
+    # Contract validating the behavior of a Criteria scope implementation.
+    module ShouldBeACriteriaScopeContract
+      extend RSpec::SleepingKingStudios::Contract
+
+      # @!method apply(example_group)
+      #   Adds the contract to the example group.
+      #
+      #   @param example_group [RSpec::Core::ExampleGroup] the example group to
+      #     which the contract is applied.
+      contract do
+        shared_context 'with criteria' do
+          let(:criteria) do
+            [
+              ['title', 'eq', 'Gideon the Ninth'],
+              ['author', 'eq', 'Tamsyn Muir']
+            ]
+          end
+        end
+
+        let(:criteria) { [] }
+
+        describe '.new' do
+          it 'should define the constructor' do
+            expect(described_class)
+              .to be_constructible
+              .with(0).arguments
+              .and_keywords(:criteria)
+              .and_any_keywords
+          end
+        end
+
+        describe '#criteria' do
+          include_examples 'should define reader', :criteria, -> { criteria }
+
+          wrap_context 'with criteria' do
+            it { expect(scope.criteria).to be == criteria }
+          end
+        end
+
+        describe '#with_criteria' do
+          let(:new_criteria) { ['author', 'eq', 'Ursula K. LeGuin'] }
+
+          it { expect(scope).to respond_to(:with_criteria).with(1).argument }
+
+          it 'should return a scope' do
+            expect(scope.with_criteria(new_criteria)).to be_a described_class
+          end
+
+          it "should not change the original scope's criteria" do
+            expect { scope.with_criteria(new_criteria) }
+              .not_to change(scope, :criteria)
+          end
+
+          it "should set the copied scope's criteria" do
+            expect(scope.with_criteria(new_criteria).criteria)
+              .to be == new_criteria
+          end
+
+          wrap_context 'with criteria' do
+            it "should not change the original scope's criteria" do
+              expect { scope.with_criteria(new_criteria) }
+                .not_to change(scope, :criteria)
+            end
+
+            it "should set the copied scope's criteria" do
+              expect(scope.with_criteria(new_criteria).criteria)
+                .to be == new_criteria
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/cuprum/collections/scope.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+require 'cuprum/collections'
+
+module Cuprum::Collections
+  # Abstract class representing a set of filters for a query.
+  class Scope; end # rubocop:disable Lint/EmptyClass
+end

lib/cuprum/collections/scopes.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+require 'cuprum/collections'
+
+module Cuprum::Collections
+  # Namespace for scope functionality, which filters query data.
+  module Scopes
+    autoload :Criteria, 'cuprum/collections/scopes/criteria'
+  end
+end

lib/cuprum/collections/scopes/criteria.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require 'cuprum/collections/scopes'
+
+module Cuprum::Collections::Scopes
+  # Functionality for implementing a criteria scope.
+  module Criteria
+    # @param criteria [Array] the criteria used for filtering query data.
+    def initialize(criteria:, **options)
+      super(**options)
+
+      @criteria = criteria
+    end
+
+    # @return [Array] the criteria used for filtering query data.
+    attr_reader :criteria
+
+    # Creates a copy of the scope with the given criteria.
+    #
+    # @param criteria [Array] the criteria used for filtering query data.
+    #
+    # @return [Scope] the copied scope.
+    def with_criteria(criteria)
+      dup.tap { |copy| copy.criteria = criteria }
+    end
+
+    protected
+
+    attr_writer :criteria
+  end
+end

spec/cuprum/collections/scopes/criteria_spec.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require 'cuprum/collections/scope'
+require 'cuprum/collections/scopes/criteria'
+require 'cuprum/collections/rspec/contracts/scope_contracts'
+
+RSpec.describe Cuprum::Collections::Scopes::Criteria do
+  include Cuprum::Collections::RSpec::Contracts::ScopeContracts
+
+  subject(:scope) { described_class.new(criteria: criteria) }
+
+  let(:described_class) { Spec::ExampleScope }
+
+  example_class 'Spec::ExampleScope', Cuprum::Collections::Scope do |klass|
+    klass.include Cuprum::Collections::Scopes::Criteria # rubocop:disable RSpec/DescribedClass
+  end
+
+  include_contract 'should be a criteria scope'
+end