1 files changed, 24 insertions, 0 deletions
diff --git a/spec/ruby/library/delegate/delegate_class/respond_to_missing_spec.rb b/spec/ruby/library/delegate/delegate_class/respond_to_missing_spec.rb
new file mode 100644
index 0000000000..3975e5208b
--- /dev/null
+++ b/spec/ruby/library/delegate/delegate_class/respond_to_missing_spec.rb
@@ -0,0 +1,24 @@
+require_relative "../../../spec_helper"
+require 'delegate'
+
+describe "DelegateClass#respond_to_missing?" do
+  it "is used for respond_to? behavior of late-bound delegated methods" do
+    # From jruby/jruby#3151:
+    # DelegateClass subtracts Delegate's public API from the target class's instance_methods
+    # to determine which methods to eagerly delegate. If respond_to_missing? shows up in
+    # instance_methods, it will get delegated and skip the delegate-aware implementation
+    # in Delegate. Any methods that must be delegated through method_missing, like methods
+    # defined after the DelegateClass is created, will fail to dispatch properly.
+
+    cls = Class.new
+    dcls = DelegateClass(cls)
+    cdcls = Class.new(dcls)
+    cdcls_obj = cdcls.new(cls.new)
+
+    cdcls_obj.respond_to?(:foo).should == false
+
+    cls.class_eval { def foo; end }
+
+    cdcls_obj.respond_to?(:foo).should == true
+  end
+end