ModelAttribute spec: Allow test to handle existing elements in `@@all`

When `ModelAttribute` instances are added to `@@all` directly in the
class, the test breaks. Make it a little more robust by checking change
in array size instead of total size.

Refs #4401

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/model_attribute.rb b/lib/model_attribute.rb
index be5caea94..b1297d43d 100644
--- a/lib/model_attribute.rb
+++ b/lib/model_attribute.rb
@@ -14,4 +14,6 @@ class ModelAttribute
     @name = name
     @data_type = data_type
   end
+
+  define :journey_pattern, :name, :string
 end