Support globally disabling memoization

Fixes #11

lib/ttl_memoizeable.rb

@@ -9,6 +9,16 @@ module TTLMemoizeable
   TTLMemoizationError = Class.new(StandardError)
   SetupMutex = Mutex.new
 
+  @disabled = false
+
+  def self.disable!
+    @disabled = true
+  end
+
+  def self.enable!
+    @disabled = false
+  end
+
   def ttl_memoized_method(method_name, ttl: 1000)
     raise TTLMemoizationError, "Method not defined: #{method_name}" unless method_defined?(method_name) || private_method_defined?(method_name)
 
@@ -60,6 +70,7 @@ def ttl_memoized_method(method_name, ttl: 1000)
       end
 
       define_method ttl_exceeded_method_name do
+        return true if TTLMemoizeable.instance_variable_get(:@disabled)
         return true unless instance_variable_defined?(value_variable_name)
 
         compared_to = time_based_ttl ? ttl.ago : 0

spec/ttl_memoizeable_spec.rb

@@ -2,6 +2,7 @@
 
 RSpec.describe TTLMemoizeable do
   before { stub_const("Klass", klass) if klass }
+  after { described_class.enable! }
 
   let(:klass) { integer_ttl_klass }
 
@@ -330,4 +331,40 @@ def bar
       end.each(&:join)
     end
   end
+
+  describe ".disable!" do
+    context "it bypasses the cached value" do
+      let(:klass) { integer_ttl_klass }
+
+      before { described_class.disable! }
+
+      it "only calls #expensive_bar twice" do
+        expect(Klass).to receive(:expensive_bar).and_call_original.exactly(11)
+
+        11.times do
+          expect(Klass.bar).to eq(1)
+        end
+      end
+    end
+  end
+
+  describe ".enable!" do
+    context "it bypasses the cached value" do
+      let(:klass) { integer_ttl_klass }
+
+      before {  }
+
+      it "only calls #expensive_bar once" do
+        expect(Klass).to receive(:expensive_bar).and_call_original.once
+
+        described_class.disable!
+        Klass.bar
+        described_class.enable!
+
+        3.times do
+          expect(Klass.bar).to eq(1)
+        end
+      end
+    end
+  end
 end