support RSpec match transition_from

CHANGELOG.md

@@ -1,5 +1,9 @@
 # CHANGELOG
 
+## unreleased
+
+ * add RSpec matcher `transition_from` (see [issue #178](https://github.com/aasm/aasm/issues/178)  for details, thanks to [@thomasstephane](https://github.com/thomasstephane))
+
 ## 4.4.1
 
  * add support for rejecting certain events on inspection (see [issue #272](https://github.com/aasm/aasm/issues/272)  for details, thanks to [@dubroe](https://github.com/dubroe))

README.md

@@ -723,28 +723,21 @@ Job.aasm.states_for_select
 
 ### Testing
 
-AASM provides matchers for [RSpec](http://rspec.info).
+AASM provides some matchers for [RSpec](http://rspec.info). Add `require 'aasm/rspec'` to your `spec_helper.rb` file and use them like this
 
-  job = Job.new
+```ruby
-  job.should have_state :sleeping
+# classes with only the default state machine
-  job.should allow_transition_to :running
+job = Job.new
-  job.should allow_event :run
+expect(job).to transition_from(:sleeping).to(:running).on_event(:run)
-  job.should allow_event :run!
+expect(job).not_to transition_from(:sleeping).to(:cleaning).on_event(:run)
-  job.should_not allow_event :clean
-  job.should_not allow_event :clean!
-
-  simple = SimpleMultipleExample.new
-  simple.should have_state :standing, :on => :move
-  simple.should allow_transition_to :walking, :on => :move
-  simple.should allow_event :run
-  simple.should allow_event :run!
-  simple.should have_state :sleeping, :on => :work
-  simple.should allow_transition_to :processing, :on => :work
-  simple.should allow_event :start
-  simple.should allow_event :start!
-  simple.should_not allow_event :stop
-  simple.should_not allow_event :stop!
 
+# classes with multiple state machine
+multiple = SimpleMultipleExample.new
+expect(multiple).to transition_from(:standing).to(:walking).on_event(:walk).on(:move)
+expect(multiple).to_not transition_from(:standing).to(:running).on_event(:walk).on(:move)
+expect(multiple).to transition_from(:sleeping).to(:processing).on_event(:start).on(:work)
+expect(multiple).to_not transition_from(:sleeping).to(:sleeping).on_event(:start).on(:work)
+```
 
 ## <a id="installation">Installation ##
 

lib/aasm/rspec.rb

@@ -0,0 +1,5 @@
+# relative-require all rspec files
+Dir[File.dirname(__FILE__) + '/rspec/*.rb'].each do |file|
+  require 'aasm/rspec/' + File.basename(file, File.extname(file))
+end
+

lib/aasm/rspec/transition_from.rb

@@ -0,0 +1,32 @@
+RSpec::Matchers.define :transition_from do |from_state|
+  match do |obj|
+    @state_machine_name ||= :default
+    obj.aasm(@state_machine_name).current_state = from_state.to_sym
+    # expect(obj).to receive(:broadcast_event).with(@event.to_s, obj, from_state, @to_state)
+    obj.send(@event) && obj.aasm(@state_machine_name).current_state == @to_state.to_sym
+  end
+
+  chain :on do |state_machine_name|
+    @state_machine_name = state_machine_name
+  end
+
+  chain :to do |state|
+    @to_state = state
+  end
+
+  chain :on_event do |event|
+    @event = event
+  end
+
+  description do
+    "transition state to :#{@to_state} from :#{expected} on event :#{@event} (on :#{@state_machine_name})"
+  end
+
+  failure_message do |obj|
+    "expected that :#{obj.aasm(@state_machine_name).current_state} would be :#{@to_state} (on :#{@state_machine_name})"
+  end
+
+  failure_message_when_negated do |obj|
+    "expected that :#{obj.aasm(@state_machine_name).current_state} would not be :#{@to_state} (on :#{@state_machine_name})"
+  end
+end

spec/spec_helper.rb

@@ -2,6 +2,7 @@ $LOAD_PATH.unshift(File.expand_path(File.dirname(__FILE__)))
 $LOAD_PATH.unshift(File.expand_path(File.join(File.dirname(__FILE__), '..', 'lib')))
 require 'aasm'
 require 'rspec'
+require 'aasm/rspec'
 
 # require 'ruby-debug'; Debugger.settings[:autoeval] = true; debugger; rubys_debugger = 'annoying'
 # require 'ruby-debug/completion'

spec/unit/rspec_matcher_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+describe 'state machine' do
+  let(:simple) { SimpleExample.new }
+  let(:multiple) { SimpleMultipleExample.new }
+
+  describe 'transition_from' do
+    it "works for simple state machines" do
+      expect(simple).to transition_from(:initialised).to(:filled_out).on_event(:fill_out)
+      expect(simple).to_not transition_from(:initialised).to(:authorised).on_event(:fill_out)
+    end
+
+    it "works for multiple state machines" do
+      expect(multiple).to transition_from(:standing).to(:walking).on_event(:walk).on(:move)
+      expect(multiple).to_not transition_from(:standing).to(:running).on_event(:walk).on(:move)
+
+      expect(multiple).to transition_from(:sleeping).to(:processing).on_event(:start).on(:work)
+      expect(multiple).to_not transition_from(:sleeping).to(:sleeping).on_event(:start).on(:work)
+    end
+  end
+end