adds new method

lib/public/versions.rb

@@ -25,6 +25,19 @@ def find!(name)
       find(name) || raise("Version '#{name}' not found")
     end
 
+    sig { params(name: String).returns(T.nilable(Version)) }
+    def find_next(name)
+      version = find!(name)
+      index = T.must(sorted_versions.index(version))
+
+      sorted_versions[index + 1]
+    end
+
+    sig { returns(T::Array[Version]) }
+    def sorted_versions
+      versions.sort
+    end
+
     private
 
     sig { returns(T::Array[Version]) }

lib/public/versions/version.rb

@@ -26,6 +26,11 @@ def to_s
       def matches?(str)
         [name, *aliases].include?(str)
       end
+
+      sig { params(other: Version).returns(T.nilable(Integer)) }
+      def <=>(other)
+        name <=> other.name
+      end
     end
   end
 end

spec/public/versions_spec.rb

@@ -6,12 +6,14 @@
 
 RSpec.describe ResourceRegistry::Versions do
   subject do
-    described_class.new(
-      versions: [
-        ResourceRegistry::Versions::Version.new('2024-01-01'),
-        ResourceRegistry::Versions::Version.new('2024-04-01', aliases: 'stable')
-      ]
-    )
+    described_class.new(versions: versions)
+  end
+
+  let(:versions) do
+    [
+      ResourceRegistry::Versions::Version.new('2024-01-01'),
+      ResourceRegistry::Versions::Version.new('2024-04-01', aliases: 'stable')
+    ]
   end
 
   describe '#find!' do
@@ -42,4 +44,38 @@
       expect(subject.find!('stable').to_s).to eq('2024-04-01')
     end
   end
+
+  describe '#find_next' do
+    context 'when given an old version' do
+      it 'returns the following version' do
+        expect(subject.find_next('2024-01-01').to_s).to eq('2024-04-01')
+      end
+    end
+
+    context 'when given the last version' do
+      it 'does not returns a version' do
+        expect(subject.find_next('2024-04-01')).to be_nil
+      end
+    end
+
+    context 'when given a random value' do
+      it 'does not returns a version' do
+        expect(subject.find_next('2024-04-01')).to be_nil
+      end
+    end
+
+    context 'when given a list of unsorted versions' do
+      let(:versions) do
+        [
+          ResourceRegistry::Versions::Version.new('2024-03-01', aliases: 'stable'),
+          ResourceRegistry::Versions::Version.new('2024-04-01', aliases: 'deprecated'),
+          ResourceRegistry::Versions::Version.new('2024-02-01')
+        ]
+      end
+
+      it 'orders and returns the following version' do
+        expect(subject.find_next('2024-02-01').to_s).to eq('2024-03-01')
+      end
+    end
+  end
 end