# Singular tests

Singular tests are simple SQL queries that return failing records of a model or a resource. They are typically used for one-off checks or specific business rules that do not require reusability.

You can use Jinja functions like `ref()` and `source()` to make reference to the target resource.

For example:

```sql
-- In the payment model, check for payment with negative amount

select *
from {{ ref('payment') }}
where amount < 0
```

## Create a singular test

To add a singular test to a model, open the **Test case template** and select the **Custom SQL** template:

<figure><img src="/files/pRvVkbgOdWSwOQ0g8GzB" alt="" width="563"><figcaption></figcaption></figure>


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