Ensure surrogate key handles single arg

integration_tests/data/sql/data_surrogate_key.csv

@@ -1,5 +1,5 @@
-field_1,field_2,field_3,expected
-a,b,c,7b193b3d33184464106f41ddf733783b
-a,,c,c5fd1b92380c6222ab0ef67839208624
-,,c,267743defab4558f1940311b66274e26
-,,,cfab1ba8c67c7c838db98d666f02a132
+column_1,column_2,column_3,expected_column_1_only,expected_all_columns
+a,b,c,0cc175b9c0f1b6a831c399e269772661,7b193b3d33184464106f41ddf733783b
+a,,c,0cc175b9c0f1b6a831c399e269772661,c5fd1b92380c6222ab0ef67839208624
+,,c,d41d8cd98f00b204e9800998ecf8427e,267743defab4558f1940311b66274e26
+,,,d41d8cd98f00b204e9800998ecf8427e,cfab1ba8c67c7c838db98d666f02a132

integration_tests/models/sql/schema.yml

@@ -104,11 +104,14 @@ models:
   - name: test_surrogate_key
     tests:
       - assert_equal:
-          actual: actual_arguments
-          expected: expected
+          actual: actual_column_1_only
+          expected: expected_column_1_only
       - assert_equal:
-          actual: actual_list
-          expected: expected
+          actual: actual_all_columns_arguments
+          expected: expected_all_columns
+      - assert_equal:
+          actual: actual_all_columns_list
+          expected: expected_all_columns
 
   - name: test_union
     tests:

integration_tests/models/sql/test_surrogate_key.sql

@@ -6,8 +6,10 @@ with data as (
 )
 
 select
-    {{ dbt_utils.surrogate_key('field_1', 'field_2', 'field_3') }} as actual_arguments,
-    {{ dbt_utils.surrogate_key(['field_1', 'field_2', 'field_3']) }} as actual_list,
-    expected
+    {{ dbt_utils.surrogate_key('column_1') }} as actual_column_1_only,
+    expected_column_1_only,
+    {{ dbt_utils.surrogate_key('column_1', 'column_2', 'column_3') }} as actual_all_columns_arguments,
+    {{ dbt_utils.surrogate_key(['column_1', 'column_2', 'column_3']) }} as actual_all_columns_list,
+    expected_all_columns
 
 from data

macros/sql/surrogate_key.sql

@@ -1,7 +1,6 @@
 {%- macro surrogate_key(field_list) -%}
 
-
-{%- if varargs|length >= 1 %}
+{%- if varargs|length >= 1 or field_list is string %}
 
 {%- do exceptions.warn("Warning: the `surrogate_key` macro now takes a single list argument instead of multiple string arguments. Support for multiple string arguments will be deprecated in a future release of dbt-utils.") -%}