Add read only adapter

lib/flipper/adapters/read_only.rb

@@ -0,0 +1,51 @@
+module Flipper
+  module Adapters
+    # Public: Adapter that wraps another adapter and raises for any writes.
+    class ReadOnly
+      include ::Flipper::Adapter
+
+      class WriteAttempted < Error
+        def initialize(message = nil)
+          super(message || "write attempted while in read only mode")
+        end
+      end
+
+      # Internal: The name of the adapter.
+      attr_reader :name
+
+      # Public
+      def initialize(adapter)
+        @adapter = adapter
+        @name = :read_only
+      end
+
+      def features
+        @adapter.features
+      end
+
+      def get(feature)
+        @adapter.get(feature)
+      end
+
+      def add(feature)
+        raise WriteAttempted
+      end
+
+      def remove(feature)
+        raise WriteAttempted
+      end
+
+      def clear(feature)
+        raise WriteAttempted
+      end
+
+      def enable(feature, gate, thing)
+        raise WriteAttempted
+      end
+
+      def disable(feature, gate, thing)
+        raise WriteAttempted
+      end
+    end
+  end
+end

spec/flipper/adapters/read_only_spec.rb

@@ -0,0 +1,94 @@
+require 'helper'
+require 'flipper/adapters/read_only'
+
+RSpec.describe Flipper::Adapters::ReadOnly do
+  let(:actor_class) { Struct.new(:flipper_id) }
+
+  let(:adapter) { Flipper::Adapters::Memory.new }
+  let(:flipper) { Flipper.new(subject) }
+  let(:feature) { flipper[:stats] }
+
+  let(:boolean_gate) { feature.gate(:boolean) }
+  let(:group_gate)   { feature.gate(:group) }
+  let(:actor_gate)   { feature.gate(:actor) }
+  let(:actors_gate)  { feature.gate(:percentage_of_actors) }
+  let(:time_gate)    { feature.gate(:percentage_of_time) }
+
+  subject { described_class.new(adapter) }
+
+  before do
+    Flipper.register(:admins) { |actor|
+      actor.respond_to?(:admin?) && actor.admin?
+    }
+
+    Flipper.register(:early_access) { |actor|
+      actor.respond_to?(:early_access?) && actor.early_access?
+    }
+  end
+
+  after do
+    Flipper.unregister_groups
+  end
+
+  it "has name that is a symbol" do
+    expect(subject.name).to_not be_nil
+    expect(subject.name).to be_instance_of(Symbol)
+  end
+
+  it "has included the flipper adapter module" do
+    expect(subject.class.ancestors).to include(Flipper::Adapter)
+  end
+
+  it "returns correct default values for the gates if none are enabled" do
+    expect(subject.get(feature)).to eq({
+      :boolean => nil,
+      :groups => Set.new,
+      :actors => Set.new,
+      :percentage_of_actors => nil,
+      :percentage_of_time => nil,
+    })
+  end
+
+  it "can get feature" do
+    actor_22 = actor_class.new('22')
+    adapter.enable(feature, boolean_gate, flipper.boolean)
+    adapter.enable(feature, group_gate, flipper.group(:admins))
+    adapter.enable(feature, actor_gate, flipper.actor(actor_22))
+    adapter.enable(feature, actors_gate, flipper.actors(25))
+    adapter.enable(feature, time_gate, flipper.time(45))
+
+    expect(subject.get(feature)).to eq({
+      :boolean => "true",
+      :groups => Set["admins"],
+      :actors => Set["22"],
+      :percentage_of_actors => "25",
+      :percentage_of_time => "45",
+    })
+  end
+
+  it "can get features" do
+    expect(subject.features).to eq(Set.new)
+    adapter.add(feature)
+    expect(subject.features).to eq(Set["stats"])
+  end
+
+  it "raises error on add" do
+    expect { subject.add(feature) }.to raise_error(Flipper::Adapters::ReadOnly::WriteAttempted)
+  end
+
+  it "raises error on remove" do
+    expect { subject.remove(feature) }.to raise_error(Flipper::Adapters::ReadOnly::WriteAttempted)
+  end
+
+  it "raises on clear" do
+    expect { subject.clear(feature) }.to raise_error(Flipper::Adapters::ReadOnly::WriteAttempted)
+  end
+
+  it "raises error on enable" do
+    expect { subject.enable(feature, boolean_gate, flipper.boolean) }.to raise_error(Flipper::Adapters::ReadOnly::WriteAttempted)
+  end
+
+  it "raises error on disable" do
+    expect { subject.disable(feature, boolean_gate, flipper.boolean) }.to raise_error(Flipper::Adapters::ReadOnly::WriteAttempted)
+  end
+end