Remove the AASM dependency

.gitignore

@@ -1,4 +1,5 @@
 *.gem
 .bundle
 Gemfile.lock
+gemfiles/aasm.gemfile.lock
 pkg

.travis.yml

@@ -1,3 +1,6 @@
 language: ruby
 rvm:
   - 2.0.0
+gemfile:
+  - Gemfile
+  - gemfiles/aasm.gemfile

README.md

@@ -63,7 +63,7 @@ An implementation of Michael Nygard's Circuit Breaker pattern.
 
 ## REQUIREMENTS:
 
-circuit_breaker has a dependency on AASM @ https://github.com/rubyist/aasm/tree/master
+None. circuit_breaker no longer depends on [AASM](https://github.com/rubyist/aasm/tree/master) but will raise AASM::InvalidTransition if that exception is defined.
 
 ## INSTALL:
 

circuit_breaker.gemspec

@@ -59,8 +59,6 @@ Gem::Specification.new do |s|
   s.extra_rdoc_files = ["History.txt", "README.txt"]
   s.rdoc_options = ["--main", "README.txt", "--charset=UTF-8"]
 
-  s.add_runtime_dependency "aasm"
-
   s.add_development_dependency "rake"
   s.add_development_dependency "rspec"
 end

gemfiles/aasm.gemfile

@@ -0,0 +1,3 @@
+eval_gemfile "../Gemfile"
+
+gem "aasm"

lib/circuit_breaker.rb

@@ -108,6 +108,7 @@ def circuit_handler_class(klass = nil)
 
 require 'circuit_breaker/circuit_handler'
 require 'circuit_breaker/circuit_broken_exception'
+require 'circuit_breaker/errors'
 require 'circuit_breaker/circuit_state'
 
 require 'circuit_breaker/trip_checker/count'

lib/circuit_breaker/circuit_state.rb

@@ -1,47 +1,14 @@
-require 'aasm'
-
 #
 # CircuitState is created individually for each object, and keeps
 # track of how the object is doing and whether the object's circuit
 # has tripped or not.
 #
 class CircuitBreaker::CircuitState
-
-  include AASM
-
-  aasm.state :half_open
-
-  aasm.state :open
-
-  aasm.state :closed, :enter => :reset_failure_count
-
-  aasm.initial_state :closed
-
-  #
-  # Trips the circuit breaker into the open state where it will immediately fail.
-  #
-  aasm.event :trip do
-    transitions :to => :open, :from => [:closed, :half_open]
-  end
-
-  #
-  # Transitions from an open state to a half_open state.
-  #
-  aasm.event :attempt_reset do
-    transitions :to => :half_open, :from => [:open]
-  end
-
-  #
-  # Close the circuit from an open or half open state.
-  #
-  aasm.event :reset do
-    transitions :to => :closed, :from => [:open, :half_open]
-  end
-
-  def initialize()
+  def initialize
     @failure_count = 0
     @last_failure_time = nil
     @call_count = 0
+    @state = :closed
   end
 
   attr_accessor :last_failure_time
@@ -67,4 +34,64 @@ def reset_counts
     reset_failure_count
     @call_count = 0
   end
+
+  def current_state
+    @state
+  end
+
+  # define #open?, :closed?, :half_open?
+  STATES = %i(open half_open closed).each do |state|
+    define_method("#{state}?") do
+      @state == state
+    end
+  end
+
+  #the state transition map, to: [:from]
+  TRANSITIONS = {
+    trip: { open: [:closed, :half_open] },
+    attempt_reset: { half_open: [:open] },
+    reset: { closed: [:open, :half_open] },
+  }
+
+  #
+  # Trips the circuit breaker into the open state where it will immediately fail.
+  #
+  def trip
+    fail invalid_transition_exception("trip") unless can_transition_to?(:trip, :open, current_state)
+    @state = :open
+  end
+  alias trip! trip
+
+  #
+  # Transitions from an open state to a half_open state.
+  #
+  def attempt_reset
+    fail invalid_transition_exception("attempt_reset") unless can_transition_to?(:attempt_reset, :half_open, current_state)
+    @state = :half_open
+  end
+
+  #
+  # Close the circuit from an open or half open state.
+  #
+  def reset
+    fail invalid_transition_exception("reset") unless can_transition_to?(:reset, :closed, current_state)
+    @state = :closed
+    reset_failure_count
+  end
+
+  private
+
+  attr_reader :state
+
+  def can_transition_to?(transition, to_state, from_state)
+    TRANSITIONS.fetch(transition).fetch(to_state).include?(from_state)
+  end
+
+  def invalid_transition_exception(event_name)
+    invalid_transition_exception_class.new(self, event_name, "circuit_state")
+  end
+
+  def invalid_transition_exception_class
+    CircuitBreaker::InvalidTransition
+  end
 end

lib/circuit_breaker/errors.rb

@@ -0,0 +1,22 @@
+module CircuitBreaker
+  begin
+    require 'aasm'
+    InvalidTransition = ::AASM::InvalidTransition
+  rescue LoadError, NameError
+    InvalidTransition = Class.new(RuntimeError) do
+      attr_reader :object, :event_name, :state_machine_name, :failures
+
+      def initialize(object, event_name, state_machine_name, failures = [])
+        @object, @event_name, @state_machine_name, @failures = object, event_name, state_machine_name, failures
+      end
+
+      def message
+        "Event '#{event_name}' cannot transition from '#{object.aasm(state_machine_name).current_state}'. #{reasoning}"
+      end
+
+      def reasoning
+        "Failed callback(s): #{@failures}." unless failures.empty?
+      end
+    end
+  end
+end

lib/circuit_breaker/version.rb

@@ -1,3 +1,3 @@
 module CircuitBreaker
-  VERSION = '1.1.2'
+  VERSION = '1.2.0'
 end

spec/circuit_breaker_spec.rb

@@ -11,56 +11,56 @@ class TestClass
    include CircuitBreaker
 
    def initialize()
-      @failure = false
-    end
-
-    def fail!
-      @failure = true
-    end
-
-    def succeed!
-      @failure = false
-    end
-
-    def call_external_method()
-      if @failure == true
-        raise "FAIL"
-      end
-
-      "hello world!"
-    end
-
-    def second_method()
-      raise 'EPIC FAIL'
-    end
-
-    def unresponsive_method
-      sleep 1.1
-      "unresponsive method returned"
-    end
-
-    def raise_specific_error_method
-      if @failure == true
-        raise SpecificException.new "SPECIFIC FAIL"
-      end
-
-      raise NotFoundException.new "NOT FOUND FAIL"
-    end
-
-    # Register this method with the circuit breaker...
-    #
-    circuit_method :call_external_method, :second_method, :unresponsive_method, :raise_specific_error_method
-
-    #
-    # Define what needs to be set for configuration...
-    #
-    circuit_handler do |handler|
-      handler.logger = Logger.new(STDOUT)
-      handler.failure_threshold = 5
-      handler.failure_timeout = 5
-      handler.invocation_timeout = 1
-      handler.excluded_exceptions = [NotFoundException]
-    end
+     @failure = false
+   end
+
+   def fail!
+     @failure = true
+   end
+
+   def succeed!
+     @failure = false
+   end
+
+   def call_external_method()
+     if @failure == true
+       raise "FAIL"
+     end
+
+     "hello world!"
+   end
+
+   def second_method()
+     raise 'EPIC FAIL'
+   end
+
+   def unresponsive_method
+     sleep 1.1
+     "unresponsive method returned"
+   end
+
+   def raise_specific_error_method
+     if @failure == true
+       raise SpecificException.new "SPECIFIC FAIL"
+     end
+
+     raise NotFoundException.new "NOT FOUND FAIL"
+   end
+
+   # Register this method with the circuit breaker...
+   #
+   circuit_method :call_external_method, :second_method, :unresponsive_method, :raise_specific_error_method
+
+   #
+   # Define what needs to be set for configuration...
+   #
+   circuit_handler do |handler|
+     handler.logger = Logger.new(STDOUT)
+     handler.failure_threshold = 5
+     handler.failure_timeout = 5
+     handler.invocation_timeout = 1
+     handler.excluded_exceptions = [NotFoundException]
+   end
 
   end
 

spec/circuit_state_spec.rb

@@ -0,0 +1,88 @@
+require 'spec_helper'
+
+describe CircuitBreaker::CircuitState do
+  subject { described_class.new }
+
+  describe "#initialize" do
+    it "sets the state to closed" do
+      expect(subject).to be_closed
+    end
+  end
+
+  shared_examples_for "trip" do
+    it "changes the state from :closed to :open" do
+      subject.trip
+      expect(subject).to be_open
+    end
+
+    it "changes the state from :half_open to :open" do
+      subject.trip
+      subject.attempt_reset
+      subject.trip
+      expect(subject).to be_open
+    end
+
+    if defined?(AASM::InvalidTransition)
+      it "when AASM is defined, raises an AASM::InvalidTransition exception if invoked from :open" do
+        subject.trip
+        expect { subject.trip }.to raise_error(AASM::InvalidTransition)
+      end
+    else
+      it "raises a CircuitBreaker::InvalidTransition exception if invoked from :open" do
+        subject.trip
+        expect { subject.trip }.to raise_error(CircuitBreaker::InvalidTransition)
+      end
+    end
+  end
+
+  describe "#trip" do
+    include_examples "trip"
+  end
+
+  describe "#trip!" do
+    include_examples "trip"
+  end
+
+  describe "#attempt_reset" do
+    it "changes the state from :open to :half_open" do
+      subject.trip
+      subject.attempt_reset
+      expect(subject).to be_half_open
+    end
+
+    it "raises an exception if invoked from :half_open" do
+      subject.trip
+      subject.attempt_reset
+      expect { subject.attempt_reset }.to raise_error(CircuitBreaker::InvalidTransition)
+    end
+
+    it "raises an exception if invoked from :closed" do
+      expect { subject.attempt_reset }.to raise_error(CircuitBreaker::InvalidTransition)
+    end
+  end
+
+  describe "#reset" do
+    it "changes the state from :open to :closed" do
+      subject.trip
+      subject.reset
+      expect(subject).to be_closed
+    end
+
+    it "changes the state from :half_open to :closed" do
+      subject.trip
+      subject.attempt_reset
+      subject.reset
+      expect(subject).to be_closed
+    end
+
+    it "raises an exception if invoked from :closed" do
+      expect { subject.reset }.to raise_error(CircuitBreaker::InvalidTransition)
+    end
+
+    it "resets the failure count" do
+      subject.trip
+      subject.reset
+      expect(subject.failure_count).to eq(0)
+    end
+  end
+end