adds tests and fixes some broken code to main language mr

app/models/project.rb

@@ -89,7 +89,7 @@ class Project < ActiveRecord::Base
   # checks if the language main language of the project changed
   before_save :check_main_language
   def check_main_language
-    if commit_count.changed?
+    if self.commit_count_changed?
       self.main_language = repository.main_language
     end
   end
@@ -955,12 +955,12 @@ class Project < ActiveRecord::Base
   end
 
   def main_language
-    language = read_attributes(:main_language)
+    language = read_attribute(:main_language)
 
     return language if language
 
     update_attributes(main_language: repository.main_language)
 
-    read_attributes(:main_language)
+    read_attribute(:main_language)
   end
 end

spec/models/project_spec.rb

@@ -560,6 +560,14 @@ describe Project, models: true do
     end
   end
 
+  describe "#main_language" do
+    let(:project) { create :project }
+    
+    it 'shows the main language of the project' do
+      expect(project.main_language).to eq("Ruby")
+    end
+  end
+
   describe '#visibility_level_allowed?' do
     let(:project) { create :project, visibility_level: Gitlab::VisibilityLevel::INTERNAL }
 

spec/models/repository_spec.rb

@@ -595,4 +595,10 @@ describe Repository, models: true do
       repository.after_remove_branch
     end
   end
+
+  describe "#main_language" do
+    it 'shows the main language of the project' do
+      expect(repository.main_language).to eq("Ruby")
+    end
+  end
 end