Add Retriable

lib/cool.rb

@@ -2,4 +2,5 @@
 
 # The list of classes in Cool module
 module Cool
+  autoload :Retriable, 'cool/retriable'
 end

lib/cool/retriable.rb

@@ -0,0 +1,21 @@
+module Cool
+  # Retriable
+  module Retriable
+    def retry_(new_method, on: StandardError, times: 3) # rubocop:disable Metrics/MethodLength, Metrics/LineLength
+      orig_method = "__retry_orig_#{new_method}".to_sym
+      alias_method orig_method, new_method
+      define_method(new_method) do |*args, &block|
+        (times - 1).times do
+          retval =
+            begin
+              method(orig_method).call(*args, &block)
+            rescue *on
+              next
+            end
+          return retval unless block_given? && yield(retval)
+        end
+        return method(orig_method).call(*args, &block)
+      end
+    end
+  end
+end

spec/lib/cool/retriable_spec.rb

@@ -0,0 +1,220 @@
+RSpec.describe Cool::Retriable do
+  describe '#retry_' do
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [:no, :no, :yes].to_enum
+        end
+
+        def do_it
+          @enum.next
+        end
+        retry_(:do_it) { |retval| retval == :no }
+      end
+
+      expect(klass.new.do_it).to eq(:yes)
+    end
+
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [:no, :no, :no].to_enum
+        end
+
+        def do_it
+          @enum.next
+        end
+        retry_(:do_it) { |retval| retval == :no }
+      end
+
+      expect(klass.new.do_it).to eq(:no)
+    end
+
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [nil, nil, :yes].to_enum
+        end
+
+        def do_it
+          @enum.next
+        end
+        retry_(:do_it, &:nil?)
+      end
+
+      expect(klass.new.do_it).to eq(:yes)
+    end
+
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [[], {}, :yes].to_enum
+        end
+
+        def do_it
+          @enum.next
+        end
+        retry_(:do_it, &:empty?)
+      end
+
+      expect(klass.new.do_it).to eq(:yes)
+    end
+
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [:no, :no, :yes].to_enum
+        end
+
+        def do_it
+          @enum.next.tap { |value| raise if value == :no }
+        end
+        retry_(:do_it)
+      end
+
+      expect(klass.new.do_it).to eq(:yes)
+    end
+
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [:no, :no, :no].to_enum
+        end
+
+        def do_it
+          @enum.next.tap { |value| raise if value == :no }
+        end
+        retry_(:do_it)
+      end
+
+      expect { klass.new.do_it }.to raise_error(StandardError)
+    end
+
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [:no].to_enum
+        end
+
+        def do_it
+          @enum.next.tap { |value| raise if value == :no }
+        end
+        retry_(:do_it, times: 1)
+      end
+
+      expect { klass.new.do_it }.to raise_error(StandardError)
+    end
+
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [:error, nil, :yes].to_enum
+        end
+
+        def do_it
+          @enum.next.tap { |value| raise if value == :error }
+        end
+        retry_(:do_it, &:nil?)
+      end
+
+      expect(klass.new.do_it).to eq(:yes)
+    end
+
+    specify do
+      retriable = described_class
+      klass = Class.new do
+        extend retriable
+
+        def initialize
+          @enum = [:yes, :error].to_enum
+        end
+
+        def do_it
+          @enum.next.tap { |value| raise if value == :error }
+        end
+        retry_(:do_it)
+      end
+
+      expect(klass.new.do_it).to eq(:yes)
+    end
+
+    specify do
+      retriable = described_class
+      error1 = Class.new(StandardError)
+      error2 = Class.new(StandardError)
+      klass = Class.new do
+        extend retriable
+
+        def initialize(error1, error2)
+          @error1 = error1
+          @error2 = error2
+          @enum = [:error1, :error2, :yes].to_enum
+        end
+
+        def do_it
+          @enum.next.tap do |value|
+            case value
+            when :error1 then raise @error1
+            when :error2 then raise @error2
+            end
+          end
+        end
+        retry_(:do_it, on: [error1, error2])
+      end
+
+      expect(klass.new(error1, error2).do_it).to eq(:yes)
+    end
+
+    specify do
+      retriable = described_class
+      error1 = Class.new(StandardError)
+      error2 = Class.new(StandardError)
+      klass = Class.new do
+        extend retriable
+
+        def initialize(error1, error2)
+          @error1 = error1
+          @error2 = error2
+          @enum = [:error1, :error2, :error, :yes].to_enum
+        end
+
+        def do_it
+          @enum.next.tap do |value|
+            case value
+            when :error1 then raise @error1
+            when :error2 then raise @error2
+            when :error then raise StandardError
+            end
+          end
+        end
+        retry_(:do_it, times: 4, on: [error1, error2])
+      end
+
+      expect { klass.new(error1, error2).do_it }.to raise_error(StandardError)
+    end
+  end
+end

spec/spec_helper.rb

@@ -88,3 +88,5 @@
   # as the one that triggered the failure.
   Kernel.srand config.seed
 end
+
+require 'cool'