Rename FLippable to FeatureGate and make flipper_group and user mutually exclusive

Signed-off-by: Rémy Coutable <remy@rymai.me>

app/models/concerns/feature_gate.rb

@@ -1,4 +1,4 @@
-module Flippable
+module FeatureGate
   def flipper_id
     return nil if new_record?
 

app/models/user.rb

@@ -11,7 +11,7 @@ class User < ActiveRecord::Base
   include CaseSensitivity
   include TokenAuthenticatable
   include IgnorableColumn
-  include Flippable
+  include FeatureGate
 
   DEFAULT_NOTIFICATION_LEVEL = :participating
 

doc/api/features.md

@@ -61,6 +61,8 @@ POST /features/:name
 | `flipper_group` | string | no | A Flipper group name |
 | `user` | string | no | A GitLab username |
 
+Note that `flipper_group` and `user` are mutually exclusive.
+
 ```bash
 curl --data "value=30" --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/features/new_library
 ```

lib/api/features.rb

@@ -42,6 +42,7 @@ module API
         requires :value, type: String, desc: '`true` or `false` to enable/disable, an integer for percentage of time'
         optional :flipper_group, type: String, desc: 'A Flipper group name'
         optional :user, type: String, desc: 'A GitLab username'
+        mutually_exclusive :flipper_group, :user
       end
       post ':name' do
         feature = Feature.get(params[:name])

spec/models/concerns/feature_gate_spec.rb

@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe FeatureGate do
+  describe 'User' do
+    describe '#flipper_id' do
+      context 'when user is not persisted' do
+        let(:user) { build(:user) }
+
+        it { expect(user.flipper_id).to be_nil }
+      end
+
+      context 'when user is persisted' do
+        let(:user) { create(:user) }
+
+        it { expect(user.flipper_id).to eq "User:#{user.id}" }
+      end
+    end
+  end
+end

spec/models/user_spec.rb

@@ -430,20 +430,6 @@ describe User, models: true do
     end
   end
 
-  describe '#flipper_id' do
-    context 'when user is not persisted' do
-      let(:user) { build(:user) }
-
-      it { expect(user.flipper_id).to be_nil }
-    end
-
-    context 'when user is persisted' do
-      let(:user) { create(:user) }
-
-      it { expect(user.flipper_id).to eq "User:#{user.id}" }
-    end
-  end
-
   describe '#generate_password' do
     it "does not generate password by default" do
       user = create(:user, password: 'abcdefghe')