(#22772) Add error checking to yaml format

This will raise a FormatError if asked to intern invalid YAML instead of an
unintelligible ruby error.

lib/puppet/network/formats.rb

@@ -3,18 +3,28 @@
 Puppet::Network::FormatHandler.create_serialized_formats(:yaml) do
   def intern(klass, text)
     data = YAML.load(text, :safe => true, :deserialize_symbols => true)
-    return data if data.is_a?(klass)
-    klass.from_pson(data)
+    data_to_instance(klass, data)
   end
 
   def intern_multiple(klass, text)
-    YAML.load(text, :safe => true, :deserialize_symbols => true).collect do |data|
-      if data.is_a?(klass)
-        data
-      else
-        klass.from_pson(data)
-      end
+    data = YAML.load(text, :safe => true, :deserialize_symbols => true)
+    unless data.respond_to?(:collect)
+      raise Puppet::Network::FormatHandler::FormatError, "Serialized YAML did not contain a collection of instances when calling intern_multiple"
+    end
+
+    data.collect do |datum|
+      data_to_instance(klass, datum)
+    end
+  end
+
+  def data_to_instance(klass, data)
+    return data if data.is_a?(klass)
+
+    unless data.is_a? Hash
+      raise Puppet::Network::FormatHandler::FormatError, "Serialized YAML did not contain a valid instance of #{klass}"
     end
+
+    klass.from_pson(data)
   end
 
   def render(instance)

spec/unit/network/formats_spec.rb

@@ -63,27 +63,31 @@ def to_pson(*args)
       @yaml.intern(String, YAML.dump(:foo)).should == "foo"
     end
 
-    it "should fail when type does not match deserialized form and has no from_pson" do
-      expect do
-        @yaml.intern(Hash, YAML.dump("foo"))
-      end.to raise_error(NoMethodError)
-    end
-
     it "should load from yaml when deserializing an array" do
       text = YAML.dump(["foo"])
       @yaml.intern_multiple(String, text).should == ["foo"]
     end
 
-    it "should fail when one element does not have a from_pson" do
+    it "fails intelligibly instead of calling to_pson with something other than a hash" do
+      expect do
+        @yaml.intern(Puppet::Node, '')
+      end.to raise_error(Puppet::Network::FormatHandler::FormatError, /did not contain a valid instance/)
+    end
+
+    it "fails intelligibly when intern_multiple is called and yaml doesn't decode to an array" do
       expect do
-        @yaml.intern_multiple(Hash, YAML.dump(["foo"]))
-      end.to raise_error(NoMethodError)
+        @yaml.intern_multiple(Puppet::Node, '')
+      end.to raise_error(Puppet::Network::FormatHandler::FormatError, /did not contain a collection/)
+    end
+
+    it "fails intelligibly instead of calling to_pson with something other than a hash when interning multiple" do
+      expect do
+        @yaml.intern_multiple(Puppet::Node, YAML.dump(["hello"]))
+      end.to raise_error(Puppet::Network::FormatHandler::FormatError, /did not contain a valid instance/)
     end
   end
 
   describe "base64 compressed yaml", :if => Puppet.features.zlib? do
-    yaml = Puppet::Network::FormatHandler.format(:b64_zlib_yaml)
-
     before do
       @yaml = Puppet::Network::FormatHandler.format(:b64_zlib_yaml)
     end
@@ -294,6 +298,12 @@ def to_pson(*args)
         PsonTest.expects(:from_pson).with("baz").returns "BAZ"
         @pson.intern_multiple(PsonTest, text).should == %w{BAR BAZ}
       end
+
+      it "fails intelligibly when given invalid data" do
+        expect do
+          @pson.intern(Puppet::Node, '')
+        end.to raise_error(PSON::ParserError, /source did not contain any PSON/)
+      end
     end
   end