Fix issue 42 (#43)

* Add IF condition to retrieve relation from deferral

* Update description for __get_relation_ref

Author: jingyu-infinitelambda

macros/artifacts/test/utilities/relation/__get_relation_ref.sql

@@ -7,6 +7,14 @@
                           database=item.database,
                           schema=item.schema,
                           identifier=item.alias or item.name) %}
+
+      {% if relation is none and item.defer_relation %}
+        {% set relation = adapter.get_relation(
+                            database=item.defer_relation.database,
+                            schema=item.defer_relation.schema,
+                            identifier=item.defer_relation.alias or item.defer_relation.name) %}
+      {% endif %}
+      
       {{ return(relation) }}
     {% endfor %}
 

macros/artifacts/test/utilities/relation/relation.yml

@@ -9,7 +9,7 @@ macros:
       Get to-relation string only applicable to the relationship test. Otherwise returns empty.
   - name: __get_relation_ref
     description: |
-      Find the ref node in `graph` variable and return the relation string if found. Otherwise empty.
+      Find the ref node in `graph` variable and return the relation string if found. If deferral is used, return the relation string based on the deferred environment. Otherwise empty.
   - name: __get_relation_source
     description: |
       Find the source node in `graph` variable and return the relation string if found. Otherwise empty.