Improve branch deletion via API

doc/api/branches.md

@@ -199,3 +199,17 @@ Parameters:
   "protected": false
 }
 ```
+
+## Delete repository branch
+
+
+```
+DELETE /projects/:id/repository/branches/:branch
+```
+
+Parameters:
+
++ `id` (required) - The ID of a project
++ `branch` (required) - The name of the branch
+
+It return 200 if succeed or 405 if failed with error message explaining reason.

lib/api/branches.rb

@@ -94,7 +94,13 @@ module API
       #   DELETE /projects/:id/repository/branches/:branch
       delete ":id/repository/branches/:branch" do
         authorize_push_project
-        DeleteBranchService.new.execute(user_project, params[:branch], current_user)
+        result = DeleteBranchService.new.execute(user_project, params[:branch], current_user)
+
+        if result[:state] == :success
+          true
+        else
+          render_api_error!(result[:message], 405)
+        end
       end
     end
   end

spec/requests/api/branches_spec.rb

@@ -91,7 +91,6 @@ describe API::API, api: true  do
     end
   end
 
-
   describe "POST /projects/:id/repository/branches" do
     it "should create a new branch" do
       post api("/projects/#{project.id}/repository/branches", user),
@@ -112,4 +111,26 @@ describe API::API, api: true  do
       response.status.should == 403
     end
   end
+
+  describe "DELETE /projects/:id/repository/branches/:branch" do
+    before { Repository.any_instance.stub(rm_branch: true) }
+
+    it "should remove branch" do
+      delete api("/projects/#{project.id}/repository/branches/new_design", user)
+      response.status.should == 200
+    end
+
+    it "should remove protected branch" do
+      project.protected_branches.create(name: 'new_design')
+      delete api("/projects/#{project.id}/repository/branches/new_design", user)
+      response.status.should == 405
+      json_response['message'].should == 'Protected branch cant be removed'
+    end
+
+    it "should not remove HEAD branch" do
+      delete api("/projects/#{project.id}/repository/branches/master", user)
+      response.status.should == 405
+      json_response['message'].should == 'Cannot remove HEAD branch'
+    end
+  end
 end