Add ProFormA serialization of exercise files

- added factories for exercises which are associated with an exercise file
- added tests for covering the ProFormA specification compliance for
  exercise files

(#17)

Author: leoselig

app/models/exercise.rb

@@ -92,6 +92,20 @@ def add_tests(test_array)
     end
   end
 
+  def build_proforma_xml_for_exercise_file(builder, exercise_file)
+    if exercise_file.main
+      proforma_file_class = 'template'
+    else
+      proforma_file_class = 'internal'
+    end
+
+    builder.file(exercise_file.content,
+      'filename' => exercise_file.full_file_name,
+      'id' => exercise_file.id,
+      'class' => proforma_file_class
+    )
+  end
+
   def to_proforma_xml
     builder = Nokogiri::XML::Builder.new do |xml|
       xml.root('xmlns:p' => 'urn:proforma:task:v0.9.4') {
@@ -102,6 +116,11 @@ def to_proforma_xml
           p.send('meta-data') {
             p.title(self.title)
           }
+          p.files {
+            self.exercise_files.all? { |file|
+              build_proforma_xml_for_exercise_file(p, file)
+            }
+          }
         }
       }
     end

spec/factories/exercise.rb

@@ -4,4 +4,34 @@
   	description 'Very descriptive'
     maxrating 10
   end
+
+  factory :exercise_with_single_java_main_file, class: 'Exercise' do
+    after(:create) do |exercise|
+       create(:single_java_main_file, exercise: exercise)
+     end
+  end
+
 end
+=begin
+category1 = LabelCategory.create(name: 'Languages')
+l1 = Label.create(name: 'Java', color: '006600', label_category: category1)
+test_framework = TestingFramework.create(name: 'JUnit 4')
+
+ExerciseFile.create(main: true, content: "public class AsteriksPattern{ public static void main String[] args) { } }", path: '', solution: false, filetype: 'java', exercise: exercise3)
+
+Test.create(content: "public class AsteriksPattern {
+  public static void main(String[] args) {
+    printAsterisk();
+  }
+  static void printAsterisk() {
+    System.out.println('*****');
+    System.out.println('*****');
+    System.out.println('*****');
+    System.out.println('*****');
+    System.out.println('*****');
+  }
+}", rating: 5, feedback_message: "Dein Pattern sieht noch nicht wie das Asteriks Pattern aus. Schaue es dir nochmal genauer an!", exercise: exercise3, testing_framework: test_framework)
+
+exercise3.labels << l1
+
+=end

spec/factories/exercise_file.rb

@@ -0,0 +1,12 @@
+FactoryGirl.define do
+
+  factory :single_java_main_file, class: 'ExerciseFile' do
+  	main true
+    content "public class AsteriksPattern{ public static void main String[] args) { } }"
+    file_name 'Main'
+    path ''
+    solution false
+    filetype 'java'
+  end
+
+end

spec/models/exercise_spec.rb

@@ -44,4 +44,68 @@
 
   end
 
+  describe 'files' do
+    let(:xml) {
+      ::Nokogiri::XML(
+      FactoryGirl.create(:only_meta_data).to_proforma_xml
+      ).xpath('/root')[0]
+    }
+
+    context 'no files' do
+
+      it 'contains a single empty <p:files>-tag' do
+        filesContainer = xml.xpath('p:task/p:files')
+        expect(filesContainer.size()).to be 1
+        allFiles = xml.xpath('p:task/*/p:file')
+        expect(allFiles.size).to be 0
+      end
+
+    end
+
+    context 'one Java main file' do
+      let(:xml) {
+        ::Nokogiri::XML(
+          FactoryGirl.create(:exercise_with_single_java_main_file).to_proforma_xml
+        ).xpath('/root')[0]
+      }
+
+      it 'has single /p:files/p:file tag' do
+        print(xml)
+        files = xml.xpath('p:task/p:files/p:file')
+        expect(files.size()).to be 1
+      end
+
+      it 'p:file tag has class="template"' do
+        filesClass = xml.xpath('p:task/p:files/p:file/@class').first
+        expect(filesClass.value).to eq 'template'
+      end
+
+      it 'has attribute id on <p:file>-tag' do
+        ids = xml.xpath('p:task/p:files/p:file/@id')
+        expect(ids.size).to be 1
+        expect(ids.first.value.size).to be > 0
+      end
+
+      it 'has attribute filename on <p:file>-tag with name and extension' do
+        file_names = xml.xpath('p:task/p:files/p:file/@filename')
+        expect(file_names.size).to be 1
+        expect(file_names.first.value).to eq 'Main.java'
+      end
+
+      it 'has attribute class="template" on <p:file>-tag because it is the main file' do
+        file_names = xml.xpath('p:task/p:files/p:file/@class')
+        expect(file_names.size).to be 1
+        expect(file_names.first.value).to eq 'template'
+      end
+
+      it '<p:file> contains file contents as plain text ' do
+        file_contents = xml.xpath('p:task/p:files/p:file/text()')
+        expect(file_contents.size).to be 1
+        expect(file_contents.first.content).to eq 'public class AsteriksPattern{ public static void main String[] args) { } }'
+      end
+
+    end
+
+  end
+
 end