Datamapper DataMapper → 0.10.0

Disclaimer: this may or may not be reproducible. I've seen it on the mysterious MacBook Pro of the no-longer elusive and mysterious mrship, but I can't make it misbehave on my own MacBook. This ticket is the origin of #952.

The spec file in the attached zip file reads as follows:

describe Parent do
  before(:each) do
    @parent = Parent.new(:name => "Homer")
    @child = Child.new(:parent => @parent, :name => "Bart")
    @parent.save
  end
  
  it "should make the belongs to not nullable" do
    @child.should be_valid # because we want @parent to tell @child who owns it
  end
end

The expectation is that it will fail. The reason is that it was written under the (false) assumption that issue #939 does not exist. However, I have observed with my own eyes that, sometimes, DataMapper does not add the presence validation for parent_id in Child. This means the spec unexpectedly passes. You can see what's going wrong with the following debug line added to DataMapper::Associations::Relationship#child_key:

# Returns a set of keys that identify child model
#
# @return   [DataMapper::PropertySet]  a set of properties that identify child model
# @api private
def child_key
  @child_key ||=
    begin
      properties = child_model.properties(child_repository_name)

      child_key = parent_key.zip(@child_properties || []).map do |parent_property, property_name|
        property_name ||= "#{property_prefix}_#{parent_property.name}".to_sym

        properties[property_name] || begin
          # create the property within the correct repository
          DataMapper.repository(child_repository_name) do
            p "Creating property #{property_name}", child_key_options(parent_property) # DEBUG
            child_model.property(property_name, parent_property.primitive, child_key_options(parent_property))
          end
        end
      end

      properties.class.new(child_key).freeze
    end
end

When it goes wrong, you can see the :nullable => false being omitted.

As I said above, this appears to be not only intermittent, but possible environment-related. I'll try to gather more information.