(#6770) Don't pollute valid face list when #face? is called.

We had two conflicting uses of the list of available faces: in the #face?
method we were perfectly happy to create a top level key on any request, but
didn't populate the version set.

Meanwhile, in #faces we treated the set of top level keys as the absolute and
correct list of all *valid* faces, leading to pain and suffering when people
queried for an invalid face, but then expected to enumerate only valid faces.

Paired-With: Matt Robinson <matt@puppetlabs.com>

2 files changed, 15 insertions, 2 deletions

diff --git a/lib/puppet/interface/face_collection.rb b/lib/puppet/interface/face_collection.rb
index 84296582c..e4eb22fa3 100644
--- a/lib/puppet/interface/face_collection.rb
+++ b/lib/puppet/interface/face_collection.rb
@@ -53,7 +53,11 @@ module Puppet::Interface::FaceCollection
 
   def self.face?(name, version)
     name = underscorize(name)
-    return true if @faces[name].has_key?(version)
+
+    # Note: be careful not to accidentally create the top level key, either,
+    # because it will result in confusion when people try to enumerate the
+    # list of valid faces later. --daniel 2011-04-11
+    return true if @faces.has_key?(name) and @faces[name].has_key?(version)
 
     # We always load the current version file; the common case is that we have
     # the expected version and any compatibility versions in the same file,
@@ -106,7 +110,11 @@ module Puppet::Interface::FaceCollection
     # but we don't need that right now.
     #
     # So, this comment is a place-holder for that.  --daniel 2011-04-06
-    return !! @faces[name].has_key?(version)
+    #
+    # Note: be careful not to accidentally create the top level key, either,
+    # because it will result in confusion when people try to enumerate the
+    # list of valid faces later. --daniel 2011-04-11
+    return !! (@faces.has_key?(name) and @faces[name].has_key?(version))
   end
 
   def self.register(face)
diff --git a/spec/unit/interface/face_collection_spec.rb b/spec/unit/interface/face_collection_spec.rb
index e6e03c3d2..752871035 100755
--- a/spec/unit/interface/face_collection_spec.rb
+++ b/spec/unit/interface/face_collection_spec.rb
@@ -138,6 +138,11 @@ describe Puppet::Interface::FaceCollection do
         subject.face?(:huzzah, :current).should be_true
       end
     end
+
+    it "should not cause an invalid face to be enumerated later" do
+      subject.face?(:there_is_no_face, :current).should be_false
+      subject.faces.should_not include :there_is_no_face
+    end
   end
 
   describe "::register" do