Implement QA pages and views validator

qa/qa.rb

@@ -74,6 +74,7 @@ module QA
     autoload :Base, 'qa/page/base'
     autoload :View, 'qa/page/view'
     autoload :Element, 'qa/page/element'
+    autoload :Validator, 'qa/page/validator'
 
     module Main
       autoload :Login, 'qa/page/main/login'

qa/qa/page/validator.rb

@@ -0,0 +1,51 @@
+module QA
+  module Page
+    class Validator
+      ValidationError = Class.new(StandardError)
+      Error = Struct.new(:page, :view, :message)
+
+      def initialize(constant)
+        @module = constant
+      end
+
+      def constants
+        @consts ||= @module.constants.map do |const|
+          @module.const_get(const)
+        end
+      end
+
+      def descendants
+        @descendants ||= constants.map do |const|
+          case const
+          when Class
+            const if const < Page::Base
+          when Module
+            Page::Validator.new(const).descendants
+          end
+        end
+
+        @descendants.flatten.compact
+      end
+
+      def errors
+        @errors ||= Array.new.tap do |errors|
+          descendants.each do |page|
+            page.views.each do |view|
+              view.errors.each do |error|
+                errors.push(Error.new(page, view, error))
+              end
+            end
+          end
+        end
+      end
+
+      def validate!
+        message = <<~EOS
+          We found validation errors!
+        EOS
+
+        raise ValidationError, message if errors.any?
+      end
+    end
+  end
+end

qa/spec/page/validator_spec.rb

@@ -0,0 +1,83 @@
+describe QA::Page::Validator do
+  describe '#constants' do
+    subject do
+      described_class.new(QA::Page::Project)
+    end
+
+    it 'returns all costants that are module children' do
+      expect(subject.constants)
+        .to include QA::Page::Project::New, QA::Page::Project::Settings
+    end
+  end
+
+  describe '#descendants' do
+    subject do
+      described_class.new(QA::Page::Project)
+    end
+
+    it 'recursively returns all descendants that are page objects' do
+      expect(subject.descendants)
+        .to include QA::Page::Project::New, QA::Page::Project::Settings::Repository
+    end
+
+    it 'does not return modules that aggregate page objects' do
+      expect(subject.descendants)
+        .not_to include QA::Page::Project::Settings
+    end
+  end
+
+  context 'when checking validation errors' do
+    let(:view) { spy('view') }
+
+    before do
+      allow(QA::Page::Admin::Settings)
+        .to receive(:views).and_return([view])
+    end
+
+    subject do
+      described_class.new(QA::Page::Admin)
+    end
+
+    context 'when there are no validation errors' do
+      before do
+        allow(view).to receive(:errors).and_return([])
+      end
+
+      describe '#errors' do
+        it 'does not return errors' do
+          expect(subject.errors).to be_empty
+        end
+      end
+
+      describe '#validate!' do
+        it 'does not raise error' do
+          expect { subject.validate! }.not_to raise_error
+        end
+      end
+    end
+
+    context 'when there are validation errors' do
+      before do
+        allow(view).to receive(:errors)
+          .and_return(['some error', 'another error'])
+      end
+
+      describe '#errors' do
+        it 'returns errors' do
+          expect(subject.errors.count).to eq 2
+        end
+      end
+
+      describe '#validate!' do
+        it 'does raises an error with descriptive message' do
+          message = <<~EOS
+            We found validation errors!
+          EOS
+
+          expect { subject.validate! }
+            .to raise_error described_class::ValidationError, message
+        end
+      end
+    end
+  end
+end