Add support for feature flags

nanoc · Jul 10, 2016 · 1bb064d · 1bb064d
1 parent b22c2d8
commit 1bb064d
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Showing 3 changed files with 41 additions and 0 deletions.
diff --git a/lib/nanoc/base.rb b/lib/nanoc/base.rb
@@ -25,6 +25,7 @@ module Nanoc::Int
 require_relative 'base/contracts_support'
 
 require_relative 'base/entities'
+require_relative 'base/feature'
 require_relative 'base/repos'
 require_relative 'base/services'
 require_relative 'base/views'
diff --git a/lib/nanoc/base/feature.rb b/lib/nanoc/base/feature.rb
@@ -0,0 +1,11 @@
+module Nanoc
+  # @api private
+  module Feature
+    TRUES = %w(y yes 1 t true).freeze
+
+    def self.enabled?(name)
+      env_name = "NANOC_FEATURE_#{name.upcase}"
+      TRUES.include?(ENV.fetch(env_name, 'f').downcase)
+    end
+  end
+end
diff --git a/spec/nanoc/base/feature_spec.rb b/spec/nanoc/base/feature_spec.rb
@@ -0,0 +1,29 @@
+describe Nanoc::Feature do
+  describe '.enabled?' do
+    subject { described_class.enabled?(feature_name) }
+
+    let(:feature_name) { 'magic' }
+
+    context 'disabled' do
+      context 'not set' do
+        it { is_expected.not_to be }
+      end
+
+      %w(0 n N no No NO false False fAlSe FALSE donkey).each do |val|
+        context "set to #{val}" do
+          before { ENV['NANOC_FEATURE_MAGIC'] = val }
+          it { is_expected.not_to be }
+        end
+      end
+    end
+
+    context 'enabled' do
+      %w(1 y Y yes yEs YES t True tRuE TRUE).each do |val|
+        context "set to #{val}" do
+          before { ENV['NANOC_FEATURE_MAGIC'] = val }
+          it { is_expected.to be }
+        end
+      end
+    end
+  end
+end