feat(ruby): check if truffleruby

lib/convenient_service/support/ruby.rb

@@ -33,6 +33,20 @@ def version
         def jruby?
           ::RUBY_PLATFORM.to_s.match?(/java/)
         end
+
+        ##
+        # Returns `true` when TruffleRuby, `false` otherwise.
+        #
+        # @return [Boolean]
+        #
+        # @internal
+        #   NOTE: Taken from irb testing. May NOT be stable.
+        #
+        #   TODO: Find a confirmation of stability.
+        #
+        def truffleruby?
+          ::RUBY_ENGINE.to_s.match?(/truffleruby/)
+        end
       end
     end
   end

spec/lib/convenient_service/support/ruby_spec.rb

@@ -58,6 +58,52 @@
         end
       end
     end
+
+    describe ".truffleruby?" do
+      context "when `::RUBY_ENGINE` is NOT valid" do
+        context "when `::RUBY_ENGINE` is `nil`" do
+          before do
+            stub_const("RUBY_ENGINE", nil)
+          end
+
+          it "returns `false`" do
+            expect(described_class.truffleruby?).to eq(false)
+          end
+        end
+
+        context "when `::RUBY_ENGINE` is empty string" do
+          before do
+            stub_const("RUBY_ENGINE", "")
+          end
+
+          it "returns `false`" do
+            expect(described_class.truffleruby?).to eq(false)
+          end
+        end
+      end
+
+      context "when `::RUBY_ENGINE` is valid" do
+        context "when `::RUBY_ENGINE` does NOT match `/truffleruby/`" do
+          before do
+            stub_const("RUBY_ENGINE", "jruby")
+          end
+
+          it "returns `false`" do
+            expect(described_class.truffleruby?).to eq(false)
+          end
+        end
+
+        context "when `::RUBY_ENGINE` matches `/truffleruby/`" do
+          before do
+            stub_const("RUBY_ENGINE", "truffleruby")
+          end
+
+          it "returns `true`" do
+            expect(described_class.truffleruby?).to eq(true)
+          end
+        end
+      end
+    end
   end
 end
 # rubocop:enable RSpec/NestedGroups