> ## Documentation Index
> Fetch the complete documentation index at: https://elementary-more-explicit-webhook-instructions.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Exposure validation test

Elementary dbt package includes **exposure validation tests, implemented as [dbt tests](https://docs.getdbt.com/docs/building-a-dbt-project/tests)**.
These tests can detect changes in your models' columns that break downstream exposures, such as BI dashboards.

## Configure your elementary exposure validation tests

Within your `models` directory, add a file called `exposures.yml`

```yml
version: 2
exposures:
  - name: customers
    label: Customer Dashboard
    type: dashboard
    maturity: high
    url: https://your.bi.tool/dashboards/1
    description: >
      Shows customer growth

    depends_on:
      - ref('customers')

    owner:
      name: Callum McData
      email: data@jaffleshop.com
```

<Tip>
  You can read up about exposures and how to add them at [dbt
  documentation](https://docs.getdbt.com/docs/build/exposures)
</Tip>

### Adding the Elementary exposure information

For each exposure you wish to verify, add a new property called `meta`:

```yml
version: 2
exposures:
  - name: customers
    label: Customer Dashboard
    type: dashboard
    maturity: high
    url: https://your.bi.tool/dashboards/1
    description: >
      Shows customer growth

    depends_on:
      - ref('customers')

    owner:
      name: Callum McData
      email: data@jaffleshop.com

    meta:
      referenced_columns:
        - column_name: "customer_id"
```

<Tip>
  In Elementary Cloud, the exposures and exposure validation tests are added
  automatically, leveraging an integration with your BI tool.
</Tip>

You can optionally also specify the column data type (`data_type`)

```yml
version: 2
- name: returned_orders
  label: Returned Orders
  type: dashboard
  maturity: high
  url: https://your.bi.tool/dashboards/2
  description: >
    Returned orders over time

  depends_on:
    - ref('returned_orders')

  owner:
    name: Callum McData
    email: data@jaffleshop.com
  meta:
    referenced_columns:
      - column_name: "order_id"
        data_type: "numeric"
```

In addition, if your exposure depends on several nodes, you can depend explicitly per column which source should be tested:

```yml
version: 2
- name: returned_orders
  label: Returned Orders
  type: dashboard
  maturity: high
  url: https://your.bi.tool/dashboards/2
  description: >
    Returned orders over time

  depends_on:
    - ref('returned_orders')
    - ref('orders')

  owner:
    name: Callum McData
    email: data@jaffleshop.com
  meta:
    referenced_columns:
      - column_name: "order_id"
        data_type: "numeric"
        node: ref('returned_orders')
      - column_name: "customer_id"
        data_type: "numeric"
        node: ref('orders')

```

### Adding the Elementary exposure tests for your module

For each module schema you wish to verify the exposure dependencies, add the elementary exposure tests:

```yml
  ...
  - name: returned_orders
    description: This table contains all of the returned orders
    config:
      tags: ["finance"]

    tests:
      - elementary.volume_anomalies:
          tags: ["table_anomalies"]
          timestamp_column: "order_date"
      - elementary.exposure_schema_validity:
          tags: [elementary]

```

We recommend adding a tag to the tests so you can execute these in a dedicated run using the selection parameter `--select tag:elementary`.

Upon running the tests, if breaking changes are detected in the model, the test will fail and in the test result query you'll be able to see the reasons:

```sql
SELECT 'customers' as exposure, 'https://your.bi.tool/dashboards/1' as url, 'different data type for the column customer_id numeric vs numeric' as error
UNION ALL SELECT 'customers' as exposure, 'https://your.bi.tool/dashboards/1' as url, 'order_id column missing in the model' as error
```

## What does it mean when a test fails?

When a test fails, it means that an exposure is potentially broken due to a missing or wrongly-typed column. Open your BI tool to validate, and if you make any changes to your dashboards be sure to update the `exposures.yml` and your model schema accordingly.