Respect pretty_print methods on delegator (#39)

lib/pp.rb

@@ -200,14 +200,17 @@ def pop_inspect_key(id)
     def pp(obj)
       # If obj is a Delegator then use the object being delegated to for cycle
       # detection
-      obj = obj.__getobj__ if defined?(::Delegator) and ::Delegator === obj
+      delegated = defined?(::Delegator) && ::Delegator === obj
+      key = delegated ? obj.__getobj__ : obj
 
-      if check_inspect_key(obj)
+      if check_inspect_key(key)
+        obj = key if delegated and !obj.respond_to?(:pretty_print_cycle)
         group {obj.pretty_print_cycle self}
         return
       end
 
-      guard_inspect(obj) do
+      guard_inspect(key) do
+        obj = key if delegated and !obj.respond_to?(:pretty_print)
         group do
           obj.pretty_print self
         rescue NoMethodError

test/test_pp.rb

@@ -310,6 +310,16 @@ def test_direct_pp
 class PPDelegateTest < Test::Unit::TestCase
   class A < DelegateClass(Array); end
 
+  class Delegated < SimpleDelegator
+    def inspect
+      "<delegated>"
+    end
+
+    def pretty_print(q)
+      q.text inspect
+    end
+  end
+
   def test_delegate
     assert_equal("[]\n", A.new([]).pretty_inspect, "[ruby-core:25804]")
   end
@@ -325,6 +335,12 @@ def test_delegate_cycle
 
     assert_equal(cycle_pretty_inspect, delegator_cycle_pretty_inspect)
   end
+
+  def test_delegate_pretty_print
+    parent = HasPrettyPrint.new nil
+    delegated = Delegated.new(parent)
+    assert_equal("<delegated>\n", delegated.pretty_inspect)
+  end
 end
 
 class PPFileStatTest < Test::Unit::TestCase