Verifier: make Verifier support old and new Verifier tokens

When we have run this code for a while, we can remove this Rails 7.0-compatible fallback code.

The links in the code comment lead to where we need to change when we upgrade, one more time.

Author: olleolleolle

lib/verifier.rb

@@ -20,7 +20,21 @@ def verify(model)
   private
 
   def verifier
-    @verifier ||= ActiveSupport::MessageVerifier.new(Rails.application.config.secret_key_base)
+    @verifier ||= begin
+      # This is a Rails 7.1 MessageVerifier, which is Rails 7.0-compatible verifier - as a fallback.
+      #
+      # Read more:
+      # https://api.rubyonrails.org/v7.0/classes/ActiveSupport/MessageVerifier.html
+      # https://api.rubyonrails.org/v7.1/classes/ActiveSupport/MessageVerifier.html
+      # https://api.rubyonrails.org/v8.0.2.1/classes/ActiveSupport/MessageVerifier.html
+
+      verifier = ActiveSupport::MessageVerifier.new(Rails.application.config.secret_key_base)
+      # Rails 7.0 default: Marshal. Rails 7.1 (the default) is :json_allow_marshal.
+      verifier.rotate(serializer: Marshal)
+      # Rails 7.0 default: "SHA1". Rails 7.1 (the default) is "SHA256".
+      verifier.rotate(digest: 'SHA1')
+      verifier
+    end
   end
 
   def generate_access_token

spec/lib/verifier_spec.rb

@@ -6,7 +6,7 @@
   end
 
   it 'generates access_token for an id' do
-    expect(Verifier.new(id: 1).access_token).to be_eql('BAhpBg==--30d45b871c77098a0ba79cf27dd532650ca75531')
+    expect(Verifier.new(id: 1).access_token).to eq('MQ==--a3487195ba15b69d4aa07b7da0234463b82c96b3')
   end
 
   it 'verifies a model' do
@@ -15,4 +15,20 @@
 
     expect(Verifier.new(token: access_token).verify(Member)).to eq(member)
   end
+
+  context 'with an access token from Rails 7.0' do
+    it 'verifies a model' do
+      member = Fabricate(:member)
+      access_token = build_access_token_from_rails70(member.id)
+
+      expect(Verifier.new(token: access_token).verify(Member)).to eq(member)
+    end
+
+    def build_access_token_from_rails70(id)
+      # Old Rails 7.0 default was Marshal. Rails 7.1 (the default) is :json_allow_marshal.
+      # Old Rails 7.0 default was "SHA1". Rails 7.1 (the default) is "SHA256".
+      verifier = ActiveSupport::MessageVerifier.new(Rails.application.config.secret_key_base, serializer: Marshal, digest: 'SHA1')
+      verifier.generate(id)
+    end
+  end
 end