Added ability to use expression_is_true as a column test (#313)

Tidy up Jinja

Update changelog

CHANGELOG.md

@@ -1,6 +1,7 @@
 # dbt-utils v0.6.5 (unreleased)
 ## Features
 * Add new `accepted_range` test ([#276](https://github.com/fishtown-analytics/dbt-utils/pull/276) [@joellabes](https://github.com/joellabes))
+* Make `expression_is_true` work as a column test (code originally in [#226](https://github.com/fishtown-analytics/dbt-utils/pull/226/) from [@elliottohara](https://github.com/elliottohara), merged via [#313]) 
 
 ## Fixes
 

README.md

@@ -181,6 +181,25 @@ models:
 
 ```
 
+This macro can also be used at the column level. When this is done, the `expression` is evaluated against the column.  
+
+```yaml
+version: 2
+models: 
+    - name: model_name
+      columns: 
+        - name: col_a
+          tests:
+            - dbt_utils.expression_is_true:
+                expression: '>= 1'
+        - name: col_b
+          tests:
+            - dbt_utils.expression_is_true:
+                expression: '= 1'
+                condition: col_a = 1
+
+```
+
 
 #### recency ([source](macros/schema_tests/recency.sql))
 This schema test asserts that there is data in the referenced model at least as recent as the defined interval prior to the current timestamp.

integration_tests/models/schema_tests/schema.yml

@@ -20,6 +20,16 @@ models:
       - dbt_utils.expression_is_true:
           expression: col_a = 0.5
           condition: col_b = 0.5
+    columns:
+      - name: col_a
+        tests:
+          - dbt_utils.expression_is_true:
+              expression: + col_b = 1
+      - name: col_b
+        tests:
+          - dbt_utils.expression_is_true:
+              expression: = 0.5
+              condition: col_a = 0.5
 
   - name: test_recency
     tests:

macros/schema_tests/expression_is_true.sql

@@ -7,6 +7,7 @@
 {% macro default__test_expression_is_true(model, condition) %}
 
 {% set expression = kwargs.get('expression', kwargs.get('arg')) %}
+{% set column_name = kwargs.get('column_name') %}
 
 with meet_condition as (
 
@@ -18,7 +19,11 @@ validation_errors as (
     select
         *
     from meet_condition
-    where not({{expression}})
+    {% if column_name is none %}
+    where not({{ expression }})
+    {%- else %}
+    where not({{ column_name }} {{ expression }})
+    {%- endif %}
 
 )