Merge pull request #32 from nave91/feature/more-tests

Test for columns with same value in all rows or no value at all

README.md

@@ -72,6 +72,31 @@ model_name:
       - ref('other_table_name')
 
 ```
+
+#### at_least_one ([source](macros/schema_tests/at_least_one.sql))
+This schema test asserts if column has at least one value. 
+
+Usage:
+```
+model_name:
+  constraints:
+    at_least_one:
+      - column_name
+
+```
+
+#### not_constant ([source](macros/schema_tests/not_constant.sql))
+This schema test asserts if column does not have same value in all rows.
+
+Usage:
+```
+model_name:
+  constraints:
+    not_constant:
+      - column_name
+
+```
+
 ---
 ### SQL helpers
 #### group_by ([source](macros/sql/groupby.sql))

macros/schema_tests/at_least_one.sql

@@ -0,0 +1,15 @@
+{% macro test_at_least_one(model, arg) %}
+
+select count(*)
+from (
+    select
+
+      count({{ arg }})
+
+    from {{ model }}
+
+    having count({{ arg }}) = 0
+
+) validation_errors
+
+{% endmacro %}

macros/schema_tests/not_constant.sql

@@ -0,0 +1,18 @@
+
+{% macro test_not_constant(model, arg) %}
+
+select count(*)
+
+from (
+
+    select
+          count(distinct {{ arg }})
+
+    from {{ model }}
+
+    having count(distinct {{ arg }}) = 1
+
+    ) validation_errors
+
+
+{% endmacro %}