feat(service): introduce ConvenientService::Service::Plugins::CanHave…

…Steps.step?

lib/convenient_service/service/plugins/can_have_steps.rb

@@ -3,3 +3,44 @@
 require_relative "can_have_steps/commands"
 require_relative "can_have_steps/concern"
 require_relative "can_have_steps/entities"
+
+module ConvenientService
+  module Service
+    module Plugins
+      module CanHaveSteps
+        class << self
+          ##
+          # Checks whether an object is a step instance.
+          #
+          # @api public
+          #
+          # @param step [Object] Can be any type.
+          # @return [Boolean]
+          #
+          # @example Simple usage.
+          #   class Service
+          #     include ConvenientService::Standard::Config
+          #
+          #     step :result
+          #
+          #     def result
+          #       success
+          #     end
+          #   end
+          #
+          #   step = Service.new.steps.first
+          #
+          #   ConvenientService::Plugins::Service::CanHaveSteps.step?(step)
+          #   # => true
+          #
+          #   ConvenientService::Plugins::Service::CanHaveSteps.step?(42)
+          #   # => false
+          #
+          def step?(step)
+            Commands::IsStep[step: step]
+          end
+        end
+      end
+    end
+  end
+end

lib/convenient_service/service/plugins/can_have_steps/commands.rb

@@ -1,3 +1,4 @@
 # frozen_string_literal: true
 
 require_relative "commands/create_step_class"
+require_relative "commands/is_step"

lib/convenient_service/service/plugins/can_have_steps/commands/is_step.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module ConvenientService
+  module Service
+    module Plugins
+      module CanHaveSteps
+        module Commands
+          class IsStep < Support::Command
+            ##
+            # @!attribute [r] step
+            #   @return [Object] Can be any type.
+            #
+            attr_reader :step
+
+            ##
+            # @param step [Object] Can be any type.
+            # @return [void]
+            #
+            def initialize(step:)
+              @step = step
+            end
+
+            ##
+            # @return [Boolean]
+            #
+            def call
+              step.class.include?(Entities::Step::Concern)
+            end
+          end
+        end
+      end
+    end
+  end
+end

spec/lib/convenient_service/service/plugins/can_have_steps/commands/is_step_spec.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+require "convenient_service"
+
+# rubocop:disable RSpec/NestedGroups
+RSpec.describe ConvenientService::Service::Plugins::CanHaveSteps::Commands::IsStep, type: :standard do
+  example_group "class methods" do
+    describe ".call" do
+      let(:command_result) { described_class.call(step: step) }
+
+      context "when `step` class does NOT include `ConvenientService::Service::Plugins::CanHaveSteps::Entities::Step::Concern`" do
+        let(:step) { 42 }
+
+        it "returns `false`" do
+          expect(command_result).to eq(false)
+        end
+      end
+
+      context "when `step` class includes `ConvenientService::Service::Plugins::CanHaveSteps::Entities::Step::Concern`" do
+        let(:service) do
+          Class.new do
+            include ConvenientService::Service::Configs::Essential
+
+            step :result
+
+            def result
+              success
+            end
+          end
+        end
+
+        let(:step) { service.new.steps.first }
+
+        it "returns `true`" do
+          expect(command_result).to eq(true)
+        end
+      end
+    end
+  end
+end
+# rubocop:enable RSpec/NestedGroups

spec/lib/convenient_service/service/plugins/can_have_steps_spec.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+require "convenient_service"
+
+# rubocop:disable RSpec/NestedGroups
+RSpec.describe ConvenientService::Service::Plugins::CanHaveSteps, type: :standard do
+  include ConvenientService::RSpec::Matchers::DelegateTo
+
+  example_group "class methods" do
+    describe ".step?" do
+      let(:service) do
+        Class.new do
+          include ConvenientService::Service::Configs::Essential
+
+          step :result
+
+          def result
+            success
+          end
+        end
+      end
+
+      let(:step) { service.new.steps.first }
+
+      specify do
+        expect { described_class.step?(step) }
+          .to delegate_to(ConvenientService::Service::Plugins::CanHaveSteps::Commands::IsStep, :call)
+          .with_arguments(step: step)
+          .and_return_its_value
+      end
+    end
+  end
+end
+# rubocop:enable RSpec/NestedGroups