[dbt] add custom tests

tests/generic/custom_relationships.sql

@@ -0,0 +1,56 @@
+{% test custom_relationships(
+    model,
+    column_name,
+    to,
+    field,
+    ignore_values=None,
+    proportion_allowed_failures=0
+) %}
+
+    {{ config(severity="error") }}
+
+    with
+        child as (
+            select {{ column_name }} as child_value
+            from {{ model }}
+            {% if ignore_values %}
+                where {{ column_name }} not in ({{ ignore_values | join(", ") }})
+            {% endif %}
+        ),
+        parent as (select {{ field }} as parent_value from {{ to }}),
+        validation as (
+            select child.child_value
+            from child
+            left join parent on child.child_value = parent.parent_value
+            where parent.parent_value is null
+        ),
+        summary as (
+            select
+                count(*) as total_missing,
+                (select count(*) from child) as total_child_records,
+                round(
+                    ((count(*) * 100) / (select count(*) from child)), 2
+                ) as failure_rate
+            from validation
+        )
+
+    select
+        total_missing,
+        total_child_records,
+        failure_rate,
+        case
+            when failure_rate > {{ proportion_allowed_failures }}
+            then
+                'Test failed: Failure rate of '
+                || failure_rate
+                || '% exceeds allowed proportion of '
+                || '{{ proportion_allowed_failures }}%'
+            else
+                'Test passed: Failure rate of '
+                || failure_rate
+                || '% within acceptable limits'
+        end as result_message
+    from summary
+    where failure_rate > {{ proportion_allowed_failures }}
+
+{% endtest %}

tests/generic/custom_unique_combination_of_columns.sql

@@ -0,0 +1,49 @@
+{% test custom_unique_combinations_of_columns(
+    model, combination_of_columns, proportion_allowed_failures=5
+) %}
+
+    {{ config(severity="error") }}
+
+    {%- set column_list = combination_of_columns %}
+    {%- set columns_csv = column_list | join(", ") %}
+
+    with
+        validation_data as (
+            select {{ columns_csv }}, count(*) as duplicates_count
+            from {{ model }}
+            group by {{ columns_csv }}
+            having count(*) > 1
+        ),
+        summary as (
+            select duplicates_count, (select count(*) from {{ model }}) as total_rows
+            from validation_data
+        ),
+
+        final_summary as (
+            select
+                duplicates_count,
+                total_rows,
+                round(((duplicates_count * 100) / total_rows), 2) as proportion
+            from summary
+        )
+
+    select
+        duplicates_count,
+        total_rows,
+        proportion,
+        case
+            when proportion > {{ proportion_allowed_failures }}
+            then
+                'Test failed: Proportion of non-unique '
+                || proportion
+                || '% exceeds allowed proportion '
+                || '{{ proportion_allowed_failures }}%'
+            else
+                'Test passed: Proportion of non-unique '
+                || proportion
+                || '% within acceptable limits'
+        end as log_message
+    from final_summary
+    where proportion > {{ proportion_allowed_failures }}
+
+{% endtest %}