feat: Implement Requirement 1.1.2 (#78)

Signed-off-by: Max VelDink <[email protected]>

Author: maxveldink

README.md

@@ -65,6 +65,30 @@ object = client.fetch_object_value(flag_key: 'object_value', default_value: JSON
 
 For complete documentation, visit: https://openfeature.dev/docs/category/concepts
 
+### Providers
+
+Providers are the abstraction layer between OpenFeature and different flag management systems.
+
+The `NoOpProvider` is an example of a minimalist provider. For complete documentation on the Provider interface, visit: https://openfeature.dev/specification/sections/providers.
+
+In addition to the `fetch_*` methods, providers can optionally implement lifecycle methods that are invoked when the underlying provider is switched out. For example:
+
+```ruby
+class MyProvider
+  def init
+    # Perform any initialization steps with flag management system here
+    # Return value is ignored
+  end
+
+  def shutdown
+    # Perform any shutdown/reclamation steps with flag management system here
+    # Return value is ignored
+  end
+end
+```
+
+**Note** The OpenFeature spec defines a lifecycle method called `initialize` to be called when a new provider is set. To avoid conflicting with the Ruby `initialize` method, this method should be named `init` when creating a provider.
+
 ## Contributing
 
 See [CONTRIBUTING.md](CONTRIBUTING.md) for details on how to contribute to the OpenFeature project.

lib/open_feature/sdk/api.rb

@@ -27,10 +27,10 @@ module SDK
     #
     #   client = OpenFeature::SDK::API.instance.build_client(name: 'my-open-feature-client')
     class API
-      include Singleton
+      include Singleton # Satisfies Flag Evaluation API Requirement 1.1.1
       extend Forwardable
 
-      def_delegators :configuration, :provider, :hooks, :context
+      def_delegators :configuration, :provider, :provider=, :hooks, :context
 
       def configuration
         @configuration ||= Configuration.new

lib/open_feature/sdk/configuration.rb

@@ -13,13 +13,26 @@ module SDK
     class Configuration
       extend Forwardable
 
-      attr_accessor :context, :provider, :hooks
+      attr_accessor :context, :hooks
+      attr_reader :provider
 
       def_delegator :@provider, :metadata
 
       def initialize
         @hooks = []
       end
+
+      # When switching providers, there are a few lifecycle methods that need to be taken care of.
+      #   1. If a provider is already set, we need to call `shutdown` on it.
+      #   2. On the new provider, call `init`.
+      #   3. Finally, set the internal provider to the new provider
+      def provider=(provider)
+        @provider.shutdown if @provider.respond_to?(:shutdown)
+
+        provider.init if provider.respond_to?(:init)
+
+        @provider = provider
+      end
     end
   end
 end

spec/open_feature/sdk/api_spec.rb

@@ -7,26 +7,6 @@
 RSpec.describe OpenFeature::SDK::API do
   subject(:api) { described_class.instance }
 
-  context "with Requirement 1.1.2" do
-    before do
-      api.configure do |config|
-        config.provider = OpenFeature::SDK::Provider::NoOpProvider.new
-      end
-    end
-
-    it do
-      expect(api).to respond_to(:provider)
-    end
-
-    it do
-      expect(api.provider).not_to be_nil
-    end
-
-    it do
-      expect(api.provider).is_a?(OpenFeature::SDK::Provider)
-    end
-  end
-
   context "with Requirement 1.1.3" do
     before do
       api.configure do |config|

spec/open_feature/sdk/configuration_spec.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe OpenFeature::SDK::Configuration do
+  subject(:configuration) { described_class.new }
+
+  describe "#provider=" do
+    context "when provider has an init method" do
+      let(:provider) { TestProvider.new }
+
+      it "inits and sets the provider" do
+        expect(provider).to receive(:init)
+
+        configuration.provider = provider
+
+        expect(configuration.provider).to be(provider)
+      end
+    end
+
+    context "when provider does not have an init method" do
+      it "sets the provider" do
+        provider = OpenFeature::SDK::Provider::NoOpProvider.new
+
+        configuration.provider = provider
+
+        expect(configuration.provider).to be(provider)
+      end
+    end
+  end
+end

spec/specification/flag_evaluation_api_spec.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "spec_helper"
+require_relative "../support/test_provider"
 
 RSpec.describe "Flag Evaluation API" do
   context "1.1 - API Initialization and Configuration" do
@@ -9,5 +10,37 @@
         expect(OpenFeature::SDK::API).to include(Singleton)
       end
     end
+
+    context "Requirement 1.1.2.1" do
+      specify "the API must define a provider mutator" do
+        provider = OpenFeature::SDK::Provider::NoOpProvider.new
+
+        OpenFeature::SDK.provider = provider
+
+        expect(OpenFeature::SDK.provider).to be(provider)
+      end
+    end
+
+    context "Requirement 1.1.2.2" do
+      specify "the provider mutator must invoke an initialize function on the provider" do
+        provider = TestProvider.new
+        expect(provider).to receive(:init)
+
+        OpenFeature::SDK.provider = provider
+      end
+    end
+
+    context "Requirement 1.1.2.3" do
+      specify "the provider mutator must invoke a shutdown function on previously registered provider" do
+        previous_provider = TestProvider.new
+        new_provider = TestProvider.new
+
+        expect(previous_provider).to receive(:shutdown)
+        expect(new_provider).not_to receive(:shutdown)
+
+        OpenFeature::SDK.provider = previous_provider
+        OpenFeature::SDK.provider = new_provider
+      end
+    end
   end
 end

spec/support/test_provider.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class TestProvider
+  def init
+  end
+
+  def shutdown
+  end
+end