[CHEF-3799] fixes TypeError for puts on VividMash

2 files changed, 21 insertions, 1 deletions

diff --git a/lib/chef/node/attribute_collections.rb b/lib/chef/node/attribute_collections.rb
index dcbb4601bd..d5d496fd60 100644
--- a/lib/chef/node/attribute_collections.rb
+++ b/lib/chef/node/attribute_collections.rb
@@ -154,7 +154,14 @@ class Chef
       alias :attribute? :has_key?
 
       def method_missing(symbol, *args)
-        if args.empty?
+        # Calling `puts arg` implicitly calls #to_ary on `arg`. If `arg` does
+        # not implement #to_ary, ruby recognizes it as a single argument, and
+        # if it returns an Array, then ruby prints each element. If we don't
+        # account for that here, we'll auto-vivify a VividMash for the key
+        # :to_ary which creates an unwanted key and raises a TypeError.
+        if symbol == :to_ary
+          super
+        elsif args.empty?
           self[symbol]
         elsif symbol.to_s =~ /=$/
           key_to_set = symbol.to_s[/^(.+)=$/, 1]
diff --git a/spec/unit/node/attribute_spec.rb b/spec/unit/node/attribute_spec.rb
index fac898be26..435dc3230c 100644
--- a/spec/unit/node/attribute_spec.rb
+++ b/spec/unit/node/attribute_spec.rb
@@ -234,6 +234,19 @@ describe Chef::Node::Attribute do
     end
   end
 
+  describe "when printing attribute components" do
+
+    it "does not cause a type error" do
+      # See CHEF-3799; IO#puts implicitly calls #to_ary on its argument. This
+      # is expected to raise a NoMethodError or return an Array. `to_ary` is
+      # the "strict" conversion method that should only be implemented by
+      # things that are truly Array-like, so NoMethodError is the right choice.
+      # (cf. there is no Hash#to_ary).
+      lambda { @attributes.default.to_ary }.should raise_error(NoMethodError)
+    end
+
+  end
+
   describe "when fetching values based on precedence" do
     before do
       @attributes.default["default"] = "cookbook default"