From b6d5a0d7fae7ef568b8fe50a34cf543dfc620dbf Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Wed, 21 Oct 2015 19:38:07 -0700
Subject: [PATCH 1/9] Add failed callback(s) into InvalidTransition exception

---
 lib/aasm/aasm.rb            |  8 ++++----
 lib/aasm/core/event.rb      |  4 ++++
 lib/aasm/core/transition.rb |  7 +++++--
 lib/aasm/errors.rb          | 12 ++++++++----
 4 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/lib/aasm/aasm.rb b/lib/aasm/aasm.rb
index cf9879c..ef4d05f 100644
--- a/lib/aasm/aasm.rb
+++ b/lib/aasm/aasm.rb
@@ -91,10 +91,10 @@ private
         if new_state_name = event.fire(self, {:may_fire => may_fire_to}, *args)
           aasm_fired(state_machine_name, event, old_state, new_state_name, options, *args, &block)
         else
-          aasm_failed(state_machine_name, event_name, old_state)
+          aasm_failed(state_machine_name, event_name, old_state, event.failed_callbacks)
         end
       else
-        aasm_failed(state_machine_name, event_name, old_state)
+        aasm_failed(state_machine_name, event_name, old_state, event.failed_callbacks)
       end
     rescue StandardError => e
       event.fire_callbacks(:error, self, e, *process_args(event, aasm(state_machine_name).current_state, *args)) || raise(e)
@@ -143,13 +143,13 @@ private
     persist_successful
   end
 
-  def aasm_failed(state_machine_name, event_name, old_state)
+  def aasm_failed(state_machine_name, event_name, old_state, failures = [])
     if self.respond_to?(:aasm_event_failed)
       self.aasm_event_failed(event_name, old_state.name)
     end
 
     if AASM::StateMachine[self.class][state_machine_name].config.whiny_transitions
-      raise AASM::InvalidTransition.new(self, event_name, state_machine_name)
+      raise AASM::InvalidTransition.new(self, event_name, state_machine_name, failures)
     else
       false
     end
diff --git a/lib/aasm/core/event.rb b/lib/aasm/core/event.rb
index 9aea427..5e076fa 100644
--- a/lib/aasm/core/event.rb
+++ b/lib/aasm/core/event.rb
@@ -72,6 +72,10 @@ module AASM::Core
       @transitions
     end
 
+    def failed_callbacks
+      @transitions.flat_map(&:failures)
+    end
+
   private
 
     def attach_event_guards(definitions)
diff --git a/lib/aasm/core/transition.rb b/lib/aasm/core/transition.rb
index d13fa9a..767ed19 100644
--- a/lib/aasm/core/transition.rb
+++ b/lib/aasm/core/transition.rb
@@ -2,12 +2,13 @@ module AASM::Core
   class Transition
     include DslHelper
 
-    attr_reader :from, :to, :event, :opts
+    attr_reader :from, :to, :event, :opts, :failures
     alias_method :options, :opts
 
     def initialize(event, opts, &block)
       add_options_from_dsl(opts, [:on_transition, :guard, :after], &block) if block
 
+      @failures = []
       @event = event
       @from = opts[:from]
       @to = opts[:to]
@@ -52,7 +53,9 @@ module AASM::Core
       case code
       when Symbol, String
         arity = record.send(:method, code.to_sym).arity
-        arity == 0 ? record.send(code) : record.send(code, *args)
+        result = (arity == 0 ? record.send(code) : result = record.send(code, *args))
+        failures << code unless result
+        result
       when Proc
         code.arity == 0 ? record.instance_exec(&code) : record.instance_exec(*args, &code)
       when Array
diff --git a/lib/aasm/errors.rb b/lib/aasm/errors.rb
index 72e2864..69d2bc3 100644
--- a/lib/aasm/errors.rb
+++ b/lib/aasm/errors.rb
@@ -3,14 +3,18 @@ module AASM
   class UnknownStateMachineError < RuntimeError; end
 
   class InvalidTransition < RuntimeError
-    attr_reader :object, :event_name, :state_machine_name
+    attr_reader :object, :event_name, :state_machine_name, :failures
 
-    def initialize(object, event_name, state_machine_name)
-      @object, @event_name, @state_machine_name = object, event_name, state_machine_name
+    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}'"
+      "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
 

From 9702bf7a888e8b482aa75074bdc27eb859a586a2 Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Thu, 22 Oct 2015 01:21:09 -0700
Subject: [PATCH 2/9] Add specs for new behavior, experiment with error
 matching

---
 lib/aasm/core/event.rb              |  2 +-
 lib/aasm/core/transition.rb         |  4 ++-
 spec/unit/callback_multiple_spec.rb | 53 +++++++++++++++++++++++------
 spec/unit/event_spec.rb             | 29 ++++++++++++++++
 spec/unit/transition_spec.rb        | 11 ++++++
 5 files changed, 86 insertions(+), 13 deletions(-)

diff --git a/lib/aasm/core/event.rb b/lib/aasm/core/event.rb
index 5e076fa..114abd0 100644
--- a/lib/aasm/core/event.rb
+++ b/lib/aasm/core/event.rb
@@ -73,7 +73,7 @@ module AASM::Core
     end
 
     def failed_callbacks
-      @transitions.flat_map(&:failures)
+      transitions.flat_map(&:failures)
     end
 
   private
diff --git a/lib/aasm/core/transition.rb b/lib/aasm/core/transition.rb
index 767ed19..449db99 100644
--- a/lib/aasm/core/transition.rb
+++ b/lib/aasm/core/transition.rb
@@ -57,7 +57,9 @@ module AASM::Core
         failures << code unless result
         result
       when Proc
-        code.arity == 0 ? record.instance_exec(&code) : record.instance_exec(*args, &code)
+        result = (code.arity == 0 ? record.instance_exec(&code) : record.instance_exec(*args, &code))
+        failures << code.source_location.join('#') unless result
+        result
       when Array
         if options[:guard]
           # invoke guard callbacks
diff --git a/spec/unit/callback_multiple_spec.rb b/spec/unit/callback_multiple_spec.rb
index c5c6ef2..8e94558 100644
--- a/spec/unit/callback_multiple_spec.rb
+++ b/spec/unit/callback_multiple_spec.rb
@@ -1,6 +1,16 @@
 require 'spec_helper'
 Dir[File.dirname(__FILE__) + "/../models/callbacks/*.rb"].sort.each { |f| require File.expand_path(f) }
 
+def safe_error(callback = nil)
+  error = nil
+  begin
+    yield
+  rescue Exception => e
+    error = e
+    return error
+  end
+end
+
 describe 'callbacks for the new DSL' do
 
   it "be called in order" do
@@ -47,9 +57,13 @@ describe 'callbacks for the new DSL' do
     expect(callback).to_not receive(:after_enter_closed)
     expect(callback).to_not receive(:after_event)
 
-    expect {
-      callback.left_close!
-    }.to raise_error(AASM::InvalidTransition)
+    error = safe_error { callback.left_close! }
+
+    expect(error.class).to eq AASM::InvalidTransition
+    expect(error.message).to eq(
+      "Event 'left_close' cannot transition from 'open'. Failed callback(s): [:after_transition, :event_guard]."
+    )
+
   end
 
   it "handles private callback methods as well" do
@@ -85,9 +99,12 @@ describe 'callbacks for the new DSL' do
         expect(callback).to_not receive(:after_event)
       end
 
-      expect {
-        callback.left_close!
-      }.to raise_error(AASM::InvalidTransition)
+      error = safe_error { callback.left_close! }
+
+      expect(error.class).to eq AASM::InvalidTransition
+      expect(error.message).to eq(
+        "Event 'left_close' cannot transition from 'open'. Failed callback(s): [:after_transition, :event_guard, :transition_guard]."
+      )
     end
 
     it "does not run transition_guard twice for multiple permitted transitions" do
@@ -133,9 +150,10 @@ describe 'callbacks for the new DSL' do
       expect(callback).to_not receive(:after_enter_closed)
       expect(callback).to_not receive(:after)
 
-      expect {
-        callback.close!
-      }.to raise_error(AASM::InvalidTransition)
+      error = safe_error(callback) { callback.close! }
+
+      expect(error.class).to eq AASM::InvalidTransition
+      expect(error.message).to eq "Event 'close' cannot transition from 'open'. Failed callback(s): [\"/Users/woodrich/Dropbox/personal/aasm/spec/models/callbacks/guard_within_block_multiple.rb#30\"]."
     end
   end
 
@@ -277,12 +295,25 @@ describe 'event callbacks' do
 
     it 'should call it when transition failed for bang fire' do
       expect(@foo).to receive(:aasm_event_failed).with(:null, :open)
-      expect {@foo.null!}.to raise_error(AASM::InvalidTransition)
+      #expect {@foo.null!}.to raise_error(AASM::InvalidTransition)
+
+      error = safe_error { @foo.null! }
+
+      expect(error.class).to eq AASM::InvalidTransition
+      expect(error.message).to eq(
+        "Event 'null' cannot transition from 'open'. Failed callback(s): [:always_false]."
+      )
+
     end
 
     it 'should call it when transition failed for non-bang fire' do
       expect(@foo).to receive(:aasm_event_failed).with(:null, :open)
-      expect {@foo.null}.to raise_error(AASM::InvalidTransition)
+      error = safe_error { @foo.null }
+
+      expect(error.class).to eq AASM::InvalidTransition
+      expect(error.message).to eq(
+        "Event 'null' cannot transition from 'open'. Failed callback(s): [:always_false]."
+      )
     end
 
     it 'should not call it if persist fails for bang fire' do
diff --git a/spec/unit/event_spec.rb b/spec/unit/event_spec.rb
index cddeea9..fa0ea9e 100644
--- a/spec/unit/event_spec.rb
+++ b/spec/unit/event_spec.rb
@@ -109,6 +109,35 @@ describe 'firing an event' do
     expect(event.fire(obj, {}, nil, 'arg1', 'arg2')).to eq(:closed)
   end
 
+  context 'when given a gaurd proc' do
+    it 'should have access to callback failures in the transitions' do
+      event = AASM::Core::Event.new(:graduate, state_machine) do
+        transitions :to => :alumni, :from => [:student, :applicant],
+          :guard => Proc.new { 1 + 1 == 3 }
+      end
+      line_number = __LINE__ - 2
+      obj = double('object', :aasm => double('aasm', :current_state => :student))
+
+      event.fire(obj, {}, nil)
+      expect(event.failed_callbacks).to eq ["#{__FILE__}##{line_number}"]
+    end
+  end
+
+  context 'when given a guard symbol' do
+    it 'should have access to callback failures in the transitions' do
+      event = AASM::Core::Event.new(:graduate, state_machine) do
+        transitions :to => :alumni, :from => [:student, :applicant],
+          guard: :paid_tuition?
+      end
+
+      obj = double('object', :aasm => double('aasm', :current_state => :student))
+      allow(obj).to receive(:paid_tuition?).and_return(false)
+
+      event.fire(obj, {}, nil)
+      expect(event.failed_callbacks).to eq [:paid_tuition?]
+    end
+  end
+
 end
 
 describe 'should fire callbacks' do
diff --git a/spec/unit/transition_spec.rb b/spec/unit/transition_spec.rb
index 3fcbca1..e841cfd 100644
--- a/spec/unit/transition_spec.rb
+++ b/spec/unit/transition_spec.rb
@@ -145,6 +145,17 @@ describe AASM::Core::Transition, '- when performing guard checks' do
     expect(st.allowed?(obj)).to be false
   end
 
+  it 'should add the name of the failed method calls to the failures instance var' do
+    opts = {:from => 'foo', :to => 'bar', :guard => :test}
+    st = AASM::Core::Transition.new(event, opts)
+
+    obj = double('object')
+    expect(obj).to receive(:test)
+
+    st.allowed?(obj)
+    expect(st.failures).to eq [:test]
+  end
+
   it 'should call the method on the object if unless is a symbol' do
     opts = {:from => 'foo', :to => 'bar', :unless => :test}
     st = AASM::Core::Transition.new(event, opts)

From 05c72837c95e7efe7f9826ed2b2185fd843c476c Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Thu, 22 Oct 2015 01:22:57 -0700
Subject: [PATCH 3/9] Fix spec

---
 spec/unit/callback_multiple_spec.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/spec/unit/callback_multiple_spec.rb b/spec/unit/callback_multiple_spec.rb
index 8e94558..77c13c9 100644
--- a/spec/unit/callback_multiple_spec.rb
+++ b/spec/unit/callback_multiple_spec.rb
@@ -312,7 +312,7 @@ describe 'event callbacks' do
 
       expect(error.class).to eq AASM::InvalidTransition
       expect(error.message).to eq(
-        "Event 'null' cannot transition from 'open'. Failed callback(s): [:always_false]."
+        "Event 'null' cannot transition from 'open'. Failed callback(s): [:always_false, :always_false]."
       )
     end
 

From 23927f1429dbd833470b51992b9dff4aabf72e86 Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Thu, 22 Oct 2015 01:37:26 -0700
Subject: [PATCH 4/9] Remove local reference in spec

---
 spec/unit/callback_multiple_spec.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/spec/unit/callback_multiple_spec.rb b/spec/unit/callback_multiple_spec.rb
index 77c13c9..0473127 100644
--- a/spec/unit/callback_multiple_spec.rb
+++ b/spec/unit/callback_multiple_spec.rb
@@ -153,7 +153,7 @@ describe 'callbacks for the new DSL' do
       error = safe_error(callback) { callback.close! }
 
       expect(error.class).to eq AASM::InvalidTransition
-      expect(error.message).to eq "Event 'close' cannot transition from 'open'. Failed callback(s): [\"/Users/woodrich/Dropbox/personal/aasm/spec/models/callbacks/guard_within_block_multiple.rb#30\"]."
+      expect(error.message[0..63]).to eq "Event 'close' cannot transition from 'open'. Failed callback(s):"
     end
   end
 

From dbaa50ddcef7a33277ef4cfa76b40b7def9c5e59 Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Thu, 22 Oct 2015 10:20:48 -0700
Subject: [PATCH 5/9] Instantiate instance variables in logical order

---
 lib/aasm/core/transition.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/aasm/core/transition.rb b/lib/aasm/core/transition.rb
index 449db99..b6db626 100644
--- a/lib/aasm/core/transition.rb
+++ b/lib/aasm/core/transition.rb
@@ -8,12 +8,12 @@ module AASM::Core
     def initialize(event, opts, &block)
       add_options_from_dsl(opts, [:on_transition, :guard, :after], &block) if block
 
-      @failures = []
       @event = event
       @from = opts[:from]
       @to = opts[:to]
       @guards = Array(opts[:guards]) + Array(opts[:guard]) + Array(opts[:if])
       @unless = Array(opts[:unless]) #TODO: This could use a better name
+      @failures = []
 
       if opts[:on_transition]
         warn '[DEPRECATION] :on_transition is deprecated, use :after instead'

From 53d333cfc5f053e44c1e00b92d579537646aae0c Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Thu, 22 Oct 2015 18:01:48 -0700
Subject: [PATCH 6/9] Move exception helper method into spec_helper

---
 spec/spec_helper.rb                 | 10 ++++++++++
 spec/unit/callback_multiple_spec.rb | 10 ----------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index f812a2c..b47d7be 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -22,3 +22,13 @@ Dir[File.dirname(__FILE__) + "/spec_helpers/**/*.rb"].sort.each { |f| require Fi
 
 # example model classes
 Dir[File.dirname(__FILE__) + "/models/*.rb"].sort.each { |f| require File.expand_path(f) }
+
+def safe_error(callback = nil)
+  error = nil
+  begin
+    yield
+  rescue Exception => e
+    error = e
+    return error
+  end
+end
diff --git a/spec/unit/callback_multiple_spec.rb b/spec/unit/callback_multiple_spec.rb
index 0473127..d025a8d 100644
--- a/spec/unit/callback_multiple_spec.rb
+++ b/spec/unit/callback_multiple_spec.rb
@@ -1,16 +1,6 @@
 require 'spec_helper'
 Dir[File.dirname(__FILE__) + "/../models/callbacks/*.rb"].sort.each { |f| require File.expand_path(f) }
 
-def safe_error(callback = nil)
-  error = nil
-  begin
-    yield
-  rescue Exception => e
-    error = e
-    return error
-  end
-end
-
 describe 'callbacks for the new DSL' do
 
   it "be called in order" do

From 892e2bc05d84a9f8ca380bd9c4a036880a59555a Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Thu, 22 Oct 2015 18:13:11 -0700
Subject: [PATCH 7/9] Clean up comments

---
 spec/spec_helper.rb                 | 2 +-
 spec/unit/callback_multiple_spec.rb | 2 --
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index b47d7be..b5d69a5 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -23,7 +23,7 @@ Dir[File.dirname(__FILE__) + "/spec_helpers/**/*.rb"].sort.each { |f| require Fi
 # example model classes
 Dir[File.dirname(__FILE__) + "/models/*.rb"].sort.each { |f| require File.expand_path(f) }
 
-def safe_error(callback = nil)
+def safe_error(callback = nil) # Need callack to maintain scope for Proc testing
   error = nil
   begin
     yield
diff --git a/spec/unit/callback_multiple_spec.rb b/spec/unit/callback_multiple_spec.rb
index d025a8d..2e0de55 100644
--- a/spec/unit/callback_multiple_spec.rb
+++ b/spec/unit/callback_multiple_spec.rb
@@ -285,8 +285,6 @@ describe 'event callbacks' do
 
     it 'should call it when transition failed for bang fire' do
       expect(@foo).to receive(:aasm_event_failed).with(:null, :open)
-      #expect {@foo.null!}.to raise_error(AASM::InvalidTransition)
-
       error = safe_error { @foo.null! }
 
       expect(error.class).to eq AASM::InvalidTransition

From bedf98a1502a0b50c6680bfc8d6caf4326919958 Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Sun, 15 Nov 2015 20:22:58 -0800
Subject: [PATCH 8/9] Conform error expectations to rspec standard, remove
 #safe_error

---
 spec/spec_helper.rb                 | 10 -------
 spec/unit/callback_multiple_spec.rb | 44 ++++++++++-------------------
 2 files changed, 15 insertions(+), 39 deletions(-)

diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index b5d69a5..f812a2c 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -22,13 +22,3 @@ Dir[File.dirname(__FILE__) + "/spec_helpers/**/*.rb"].sort.each { |f| require Fi
 
 # example model classes
 Dir[File.dirname(__FILE__) + "/models/*.rb"].sort.each { |f| require File.expand_path(f) }
-
-def safe_error(callback = nil) # Need callack to maintain scope for Proc testing
-  error = nil
-  begin
-    yield
-  rescue Exception => e
-    error = e
-    return error
-  end
-end
diff --git a/spec/unit/callback_multiple_spec.rb b/spec/unit/callback_multiple_spec.rb
index 2e0de55..d7fe11f 100644
--- a/spec/unit/callback_multiple_spec.rb
+++ b/spec/unit/callback_multiple_spec.rb
@@ -47,12 +47,9 @@ describe 'callbacks for the new DSL' do
     expect(callback).to_not receive(:after_enter_closed)
     expect(callback).to_not receive(:after_event)
 
-    error = safe_error { callback.left_close! }
-
-    expect(error.class).to eq AASM::InvalidTransition
-    expect(error.message).to eq(
-      "Event 'left_close' cannot transition from 'open'. Failed callback(s): [:after_transition, :event_guard]."
-    )
+    expect {
+      callback.left_close!
+    }.to raise_error(AASM::InvalidTransition, "Event 'left_close' cannot transition from 'open'. Failed callback(s): [:after_transition, :event_guard].")
 
   end
 
@@ -89,12 +86,9 @@ describe 'callbacks for the new DSL' do
         expect(callback).to_not receive(:after_event)
       end
 
-      error = safe_error { callback.left_close! }
-
-      expect(error.class).to eq AASM::InvalidTransition
-      expect(error.message).to eq(
-        "Event 'left_close' cannot transition from 'open'. Failed callback(s): [:after_transition, :event_guard, :transition_guard]."
-      )
+      expect {
+        callback.left_close!
+      }.to raise_error(AASM::InvalidTransition, "Event 'left_close' cannot transition from 'open'. Failed callback(s): [:after_transition, :event_guard, :transition_guard].")
     end
 
     it "does not run transition_guard twice for multiple permitted transitions" do
@@ -139,11 +133,10 @@ describe 'callbacks for the new DSL' do
       expect(callback).to_not receive(:after_exit_open)
       expect(callback).to_not receive(:after_enter_closed)
       expect(callback).to_not receive(:after)
+      expect {
+        callback.close!
+      }.to raise_error(AASM::InvalidTransition)
 
-      error = safe_error(callback) { callback.close! }
-
-      expect(error.class).to eq AASM::InvalidTransition
-      expect(error.message[0..63]).to eq "Event 'close' cannot transition from 'open'. Failed callback(s):"
     end
   end
 
@@ -285,23 +278,16 @@ describe 'event callbacks' do
 
     it 'should call it when transition failed for bang fire' do
       expect(@foo).to receive(:aasm_event_failed).with(:null, :open)
-      error = safe_error { @foo.null! }
-
-      expect(error.class).to eq AASM::InvalidTransition
-      expect(error.message).to eq(
-        "Event 'null' cannot transition from 'open'. Failed callback(s): [:always_false]."
-      )
-
+      expect{
+        @foo.null!
+      }.to raise_error(AASM::InvalidTransition, "Event 'null' cannot transition from 'open'. Failed callback(s): [:always_false].")
     end
 
     it 'should call it when transition failed for non-bang fire' do
       expect(@foo).to receive(:aasm_event_failed).with(:null, :open)
-      error = safe_error { @foo.null }
-
-      expect(error.class).to eq AASM::InvalidTransition
-      expect(error.message).to eq(
-        "Event 'null' cannot transition from 'open'. Failed callback(s): [:always_false, :always_false]."
-      )
+      expect{
+        @foo.null
+      }.to raise_error(AASM::InvalidTransition, "Event 'null' cannot transition from 'open'. Failed callback(s): [:always_false, :always_false].")
     end
 
     it 'should not call it if persist fails for bang fire' do

From 134129ee8235eba9b6aa1f773c35bfa0c90d6914 Mon Sep 17 00:00:00 2001
From: Chris Woodrich <cwoodrich@doximity.com>
Date: Sun, 10 Jan 2016 15:13:38 -0800
Subject: [PATCH 9/9] Restructure error sentence per @alto  suggestion Fix
 failing spec by adding period Use upstream version of Proc handling Fix
 spacing Restart travis

---
 lib/aasm/core/transition.rb  | 2 +-
 lib/aasm/errors.rb           | 4 ++--
 spec/unit/transition_spec.rb | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/aasm/core/transition.rb b/lib/aasm/core/transition.rb
index b5b7033..87bd0e0 100644
--- a/lib/aasm/core/transition.rb
+++ b/lib/aasm/core/transition.rb
@@ -58,7 +58,7 @@ module AASM::Core
         failures << code unless result
         result
       when Proc
-        result = (code.arity == 0 ? record.instance_exec(&code) : record.instance_exec(*args, &code))
+        result = (code.parameters.size == 0 ? record.instance_exec(&code) : record.instance_exec(*args, &code))
         failures << code.source_location.join('#') unless result
         result
       when Array
diff --git a/lib/aasm/errors.rb b/lib/aasm/errors.rb
index 69d2bc3..d9b5792 100644
--- a/lib/aasm/errors.rb
+++ b/lib/aasm/errors.rb
@@ -10,11 +10,11 @@ module AASM
     end
 
     def message
-      "Event '#{event_name}' cannot transition from '#{object.aasm(state_machine_name).current_state}'#{reasoning}"
+      "Event '#{event_name}' cannot transition from '#{object.aasm(state_machine_name).current_state}'. #{reasoning}"
     end
 
     def reasoning
-      ". Failed callback(s): #{@failures}." unless failures.empty?
+      "Failed callback(s): #{@failures}." unless failures.empty?
     end
   end
 
diff --git a/spec/unit/transition_spec.rb b/spec/unit/transition_spec.rb
index ec9205f..05b313b 100644
--- a/spec/unit/transition_spec.rb
+++ b/spec/unit/transition_spec.rb
@@ -6,7 +6,7 @@ describe 'transitions' do
     process = ProcessWithNewDsl.new
     expect { process.stop! }.to raise_error do |err|
       expect(err.class).to eql(AASM::InvalidTransition)
-      expect(err.message).to eql("Event 'stop' cannot transition from 'sleeping'")
+      expect(err.message).to eql("Event 'stop' cannot transition from 'sleeping'. ")
       expect(err.object).to eql(process)
       expect(err.event_name).to eql(:stop)
     end