Add delete feature to variables API

lib/api/variables.rb

@@ -57,6 +57,18 @@ module API
         present variable, with: Entities::Variable
       end
+
+      # Delete existing variable of a project
+      #
+      # Parameters:
+      #   id (required) - The ID of a project
+      #   variable_id (required) - The ID of a variable
+      # Exanoke Reqyest:
+      #   DELETE /projects/:id/variables/:variable_id
+      delete ':id/variables/:variable_id' do
+        variable = user_project.variables.where(id: params[:variable_id].to_i).first
+        variable.destroy
+      end
     end
   end
 end

spec/requests/api/variables_spec.rb

@@ -101,11 +101,38 @@ describe API::API, api: true do
     end
     context 'unauthorized user' do
-      it 'should not return project variable details' do
+      it 'should not update variable' do
         put api("/projects/#{project.id}/variables/#{variable.id}")
         expect(response.status).to eq(401)
       end
     end
   end
+
+  describe 'DELETE /projects/:id/variables/:variable_id' do
+    context 'authorized user with proper permissions' do
+      it 'should delete variable' do
+        expect do
+          delete api("/projects/#{project.id}/variables/#{variable.id}", user)
+        end.to change{project.variables.count}.by(-1)
+        expect(response.status).to eq(200)
+      end
+    end
+
+    context 'authorized user with invalid permissions' do
+      it 'should not delete variable' do
+        delete api("/projects/#{project.id}/variables/#{variable.id}", user2)
+
+        expect(response.status).to eq(403)
+      end
+    end
+
+    context 'unauthorized user' do
+      it 'should not delete variable' do
+        delete api("/projects/#{project.id}/variables/#{variable.id}")
+
+        expect(response.status).to eq(401)
+      end
+    end
+  end
 end