Jmcneill/expression is true tweak (dbt-labs#507)

* Update README.md

* add some flexibility to expression_is_true execution plan and add a few new tests

* catch duplicate field name exception when the expression_is_true test is invoked

* expression is true - rename seeds, format sql and get rid of dupe column handler from PR comments

Co-authored-by: Joel Labes <joel.labes@dbtlabs.com>

integration_tests/data/schema_tests/data_test_expression_is_true_window_functions.csv

@@ -0,0 +1,5 @@
+col_a,col_b,col_c
+1,10,15
+1,5,15
+2,16,24
+2,8,24

integration_tests/models/generic_tests/schema.yml

@@ -31,6 +31,21 @@ models:
               expression: = 0.5
               condition: col_a = 0.5
 
+  - name: data_test_expression_is_true_window_functions
+    tests:
+      - dbt_utils.expression_is_true:
+          expression: count(*) over (partition by col_a) = 2
+      - dbt_utils.expression_is_true:
+          expression: max(col_c) over (partition by col_a) = min(col_c) over (partition by col_a)
+      - dbt_utils.expression_is_true:
+          expression: sum(col_b) over (partition by col_a) = 15
+          condition: col_a = 1
+    columns:
+      - name: col_c
+        tests:
+          - dbt_utils.expression_is_true:
+              expression: = sum(col_b) over (partition by col_a)
+
   - name: test_recency
     tests:
       - dbt_utils.recency:

macros/generic_tests/expression_is_true.sql

@@ -7,16 +7,19 @@
 {% macro default__test_expression_is_true(model, expression, column_name, condition) %}
 
 with meet_condition as (
-    select * from {{ model }} where {{ condition }}
+    select
+      *,
+      {% if column_name is none %}
+      {{ expression }}
+      {%- else %}
+      {{ column_name }} {{ expression }}
+      {%- endif %}
+      as _dbt_utils_test_expression_passed
+    from {{ model }}
+    where {{ condition }}
 )
 
-select
-    *
-from meet_condition
-{% if column_name is none %}
-where not({{ expression }})
-{%- else %}
-where not({{ column_name }} {{ expression }})
-{%- endif %}
+select * from meet_condition
+where not(_dbt_utils_test_expression_passed)
 
 {% endmacro %}