Allow finding of the latest stable release.

lib/shopify_api/api_version.rb

@@ -30,6 +30,10 @@ module ShopifyAPI
       define_version(Unstable.new)
     end
 
+    def self.latest_stable_version
+      @versions.values.select(&:stable?).sort.last
+    end
+
     def to_s
       @version_name
     end
@@ -51,6 +55,10 @@ module ShopifyAPI
       numeric_version <=> other.numeric_version
     end
 
+    def stable?
+      false
+    end
+
     def construct_api_path(_path)
       raise NotImplementedError
     end
@@ -109,6 +117,10 @@ module ShopifyAPI
         @numeric_version = version_number.tr('-', '').to_i
       end
 
+      def stable?
+        true
+      end
+
       def construct_api_path(path)
         "#{@url}#{path}"
       end

test/api_version_test.rb

@@ -106,6 +106,15 @@ class ApiVersionTest < Test::Unit::TestCase
     refute_equal version_2, version_1
   end
 
+  test 'release verions are stable' do
+    assert_predicate ShopifyAPI::ApiVersion::Release.new('2019-11'), :stable?
+  end
+
+  test 'no release version are not stable' do
+    refute_predicate ShopifyAPI::ApiVersion::NoVersion.new, :stable?
+    refute_predicate ShopifyAPI::ApiVersion::Unstable.new, :stable?
+  end
+
   test 'release versions are ordered by version number with unstable always being the newest and no version always being the oldest' do
     version_1 = ShopifyAPI::ApiVersion::Release.new('2017-11')
     version_2 = ShopifyAPI::ApiVersion::Release.new('2019-11')
@@ -131,6 +140,21 @@ class ApiVersionTest < Test::Unit::TestCase
     ].sort)
   end
 
+  test 'latest_stable_version will return the version that is newest and stable' do
+    ShopifyAPI::ApiVersion.clear_defined_versions
+    ShopifyAPI::ApiVersion.define_version(ShopifyAPI::ApiVersion::Release.new('2017-11'))
+    ShopifyAPI::ApiVersion.define_version(ShopifyAPI::ApiVersion::Release.new('2019-11'))
+    ShopifyAPI::ApiVersion.define_version(ShopifyAPI::ApiVersion::Release.new('2039-01'))
+    ShopifyAPI::ApiVersion.define_version(ShopifyAPI::ApiVersion::Release.new('2039-02'))
+    ShopifyAPI::ApiVersion.define_version(ShopifyAPI::ApiVersion::Unstable.new)
+    ShopifyAPI::ApiVersion.define_version(ShopifyAPI::ApiVersion::NoVersion.new)
+
+    assert_equal(
+      ShopifyAPI::ApiVersion::Release.new('2039-02'),
+      ShopifyAPI::ApiVersion.latest_stable_version
+    )
+  end
+
   class TestApiVersion < ShopifyAPI::ApiVersion
     def initialize(name)
       @version_name = name