Merge pull request #183 from clonezone/paranoid-to_hash

Be careful about invoking #to_hash on arbitrary objects.

lib/awesome_print/formatter.rb

@@ -62,9 +62,9 @@ module AwesomePrint
     #------------------------------------------------------------------------------
     def awesome_self(object, type)
       if @options[:raw] && object.instance_variables.any?
-        awesome_object(object)
-      elsif object.respond_to?(:to_hash)
-        awesome_hash(object.to_hash)
+        return awesome_object(object)
+      elsif hash = convert_to_hash(object)
+        awesome_hash(hash)
       else
         colorize(object.inspect.to_s, type)
       end
@@ -318,6 +318,22 @@ module AwesomePrint
 
     # Utility methods.
     #------------------------------------------------------------------------------
+    def convert_to_hash(object)
+      if ! object.respond_to?(:to_hash)
+        return nil
+      end
+      if object.method(:to_hash).arity != 0
+        return nil
+      end
+
+      hash = object.to_hash
+      if ! hash.respond_to?(:keys) || ! hash.respond_to?('[]')
+        return nil
+      end
+
+      return hash
+    end
+
     def align(value, width)
       if @options[:multiline]
         if @options[:indent] > 0

spec/formats_spec.rb

@@ -708,5 +708,56 @@ EOS
       my = My.new
       expect { my.methods.ai(:plain => true) }.not_to raise_error
     end
+
+    describe "should handle a class that defines its own #to_hash method" do
+      it "that takes arguments" do
+        class My
+          def to_hash(a, b)
+          end
+        end
+
+        my = My.new
+        expect { my.ai(:plain => true) }.not_to raise_error
+      end
+
+      it "that returns nil" do
+        class My
+          def to_hash()
+            return nil
+          end
+        end
+
+        my = My.new
+        expect { my.ai(:plain => true) }.not_to raise_error
+      end
+
+      it "that returns an object that doesn't support #keys" do
+        class My
+          def to_hash()
+            object = Object.new
+            object.define_singleton_method('[]') { return nil }
+
+            return object
+          end
+        end
+
+        my = My.new
+        expect { my.ai(:plain => true) }.not_to raise_error
+      end
+
+      it "that returns an object that doesn't support subscripting" do
+        class My
+          def to_hash()
+            object = Object.new
+            object.define_singleton_method(:keys) { return [:foo] }
+
+            return object
+          end
+        end
+
+        my = My.new
+        expect { my.ai(:plain => true) }.not_to raise_error
+      end
+    end
   end
 end