From 6c298acdef5bca6c61626558c6af7447ab6f1fac Mon Sep 17 00:00:00 2001
From: Jakub Pavlik <severus@post.cz>
Date: Mon, 3 Apr 2023 00:14:26 +0200
Subject: [PATCH] Rank, AbstractDate: fix exception on comparison

with instance of a different class
---
 lib/calendarium-romanum/abstract_date.rb | 2 ++
 lib/calendarium-romanum/rank.rb          | 2 ++
 spec/abstract_date_spec.rb               | 1 +
 spec/rank_spec.rb                        | 1 +
 4 files changed, 6 insertions(+)

diff --git a/lib/calendarium-romanum/abstract_date.rb b/lib/calendarium-romanum/abstract_date.rb
index 009e7c66..e1495653 100644
--- a/lib/calendarium-romanum/abstract_date.rb
+++ b/lib/calendarium-romanum/abstract_date.rb
@@ -25,6 +25,8 @@ def self.from_date(date)
     attr_reader :month, :day
 
     def <=>(other)
+      return nil unless other.class == self.class
+
       if month != other.month
         month <=> other.month
       else
diff --git a/lib/calendarium-romanum/rank.rb b/lib/calendarium-romanum/rank.rb
index 4f18542a..85c19774 100644
--- a/lib/calendarium-romanum/rank.rb
+++ b/lib/calendarium-romanum/rank.rb
@@ -44,6 +44,8 @@ def short_desc
     end
 
     def <=>(other)
+      return nil unless other.class == self.class
+
       other.priority <=> priority
     end
 
diff --git a/spec/abstract_date_spec.rb b/spec/abstract_date_spec.rb
index 41a65fa5..de726d86 100644
--- a/spec/abstract_date_spec.rb
+++ b/spec/abstract_date_spec.rb
@@ -59,6 +59,7 @@
   describe '#==' do
     it { expect(AD.new(1, 1)).to be == AD.new(1, 1) }
     it { expect(AD.new(1, 1)).not_to be == AD.new(1, 2) }
+    it { expect(AD.new(1, 1) == 'instance of another class').to be false }
   end
 
   describe 'as a Hash key' do
diff --git a/spec/rank_spec.rb b/spec/rank_spec.rb
index 32976b31..401fd111 100644
--- a/spec/rank_spec.rb
+++ b/spec/rank_spec.rb
@@ -26,6 +26,7 @@
   describe '#==' do
     it { expect(CR::Ranks[1.2]).to be == CR::Ranks[1.2] }
     it { expect(CR::Ranks[1.2]).not_to be == CR::Ranks[1.1] }
+    it { expect(CR::Ranks::FERIAL == 'instance of another class').to be false }
   end
 
   describe 'descriptions' do