Cast string to symbol in fire/fire!, and fix deceptive error class and message (#788)

* Cast string to sym when checking event in `fire`

* Return early from method if event found

* Change message to reference Event, not State

* Add UndefinedEvent exception

Previously the code raised "UndefinedState" when it failed to find an
Event. This is confusing but was already released to the public. So this
adds UndefinedEvent as a subclass of UndefinedState and raises it
instead.

* Update Changelog

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## unreleased
 
+* Allow `fire` and `fire!` to accept a String or Symbol for the event name, and raise AASM::UndefinedEvent rather than AASM::UndefinedState
+  when an event can not be found, thanks to [norman](https://github.com/norman).
+
 ## 5.3.0
 
 * Add Ruby 3.1 and Rails 7 to the CI matrix [#775](https://github.com/aasm/aasm/pull/775), thanks to [petergoldstein](https://github.com/petergoldstein)

lib/aasm/errors.rb

@@ -17,5 +17,6 @@ module AASM
   end
 
   class UndefinedState < RuntimeError; end
+  class UndefinedEvent < UndefinedState; end
   class NoDirectAssignmentError < RuntimeError; end
 end

lib/aasm/instance_base.rb

@@ -134,10 +134,11 @@ module AASM
     private
 
     def event_exists?(event_name, bang = false)
-      event = @instance.class.aasm(@name).state_machine.events[event_name]
-      event_error = bang ? "#{event_name}!" : event_name
+      event = @instance.class.aasm(@name).state_machine.events[event_name.to_sym]
+      return true if event
 
-      raise AASM::UndefinedState, "State :#{event_error} doesn't exist" if event.nil?
+      event_error = bang ? "#{event_name}!" : event_name
+      raise AASM::UndefinedEvent, "Event :#{event_error} doesn't exist" if event.nil?
     end
   end
 end

spec/unit/callbacks_spec.rb

@@ -153,11 +153,11 @@ describe 'callbacks for the new DSL' do
 
     expect {
       callback.aasm.fire(:unknown)
-    }.to raise_error(AASM::UndefinedState, "State :unknown doesn't exist")
+    }.to raise_error(AASM::UndefinedEvent, "Event :unknown doesn't exist")
 
     expect {
       callback.aasm.fire!(:unknown)
-    }.to raise_error(AASM::UndefinedState, "State :unknown! doesn't exist")
+    }.to raise_error(AASM::UndefinedEvent, "Event :unknown! doesn't exist")
   end
 
   it "does not run any state callback if the event guard fails" do

spec/unit/complex_example_spec.rb

@@ -92,10 +92,10 @@ describe 'when being unsuspended' do
   end
 
   it "should raise AASM::UndefinedState when firing unknown events" do
-    expect { auth.aasm.fire(:unknown) }.to raise_error(AASM::UndefinedState, "State :unknown doesn't exist")
+    expect { auth.aasm.fire(:unknown) }.to raise_error(AASM::UndefinedEvent, "Event :unknown doesn't exist")
   end
 
   it "should raise AASM::UndefinedState when firing unknown bang events" do
-    expect { auth.aasm.fire!(:unknown) }.to raise_error(AASM::UndefinedState, "State :unknown! doesn't exist")
+    expect { auth.aasm.fire!(:unknown) }.to raise_error(AASM::UndefinedEvent, "Event :unknown! doesn't exist")
   end
 end

spec/unit/event_spec.rb

@@ -296,16 +296,33 @@ describe 'current event' do
   end
 
   describe "when calling events with fire/fire!" do
-    it "fire should populate aasm.current_event and transition (sleeping to showering)" do
+    context "fire" do
+      it "should populate aasm.current_event and transition (sleeping to showering)" do
         pe.aasm.fire(:wakeup)
         expect(pe.aasm.current_event).to eq :wakeup
         expect(pe.aasm.current_state).to eq :showering
       end
-    it "fire! should populate aasm.current_event and transition (sleeping to showering)" do
+
+      it "should allow event names as strings" do
+        pe.aasm.fire("wakeup")
+        expect(pe.aasm.current_event).to eq :wakeup
+        expect(pe.aasm.current_state).to eq :showering
+      end
+    end
+
+    context "fire!" do
+      it "should populate aasm.current_event and transition (sleeping to showering)" do
         pe.aasm.fire!(:wakeup)
         expect(pe.aasm.current_event).to eq :wakeup!
         expect(pe.aasm.current_state).to eq :showering
       end
+
+      it "should allow event names as strings" do
+        pe.aasm.fire!("wakeup")
+        expect(pe.aasm.current_event).to eq :wakeup!
+        expect(pe.aasm.current_state).to eq :showering
+      end
+    end
   end
 end