---
title: "Adding Elementary Tests"
sidebarTitle: "Elementary tests"
---

This tutorial will add a few common tests to our data set.
To read more about Elementary's suite of tests click [here](/data-tests/add-elementary-tests). <br/>

There are 3 models in our tutorial:<br/>

- **Customers**
- **Orders**
- **Returned Orders**

In Elementary Data, tests are added to the `schema.yml` file. We will now navigate there and add tests for each of our models.

<Warning>
A `schema.yml` file that includes all the below tests can be found at the bottom of this page, so there is no need to manually add each test.
</Warning>
<br/>
<Accordion title="Test 1: Customer Signups">
First, we will use the **tables_anomalies** test to perform a **row_count**. This tests counts the number of rows created in a given period to determine if there have been any anomalies in the number of signups in a given time period.

We will add the **volume_anomalies** test as follows:

```yaml
models:
  - name: customers
    description: This table has basic information about a customer, as well as some derived facts based on a customer's orders
    config:
      tags: ["PII"]
    tests:
      - elementary.volume_anomalies
```

Now that we have configured a test, we should define a column to use for our timestamp. This will be used to create time buckets for anomaly detection. We select the **signup_date** column as seen below:

```yaml
models:
  - name: customers
    description: This table has basic information about a customer, as well as some derived facts based on a customer's orders
    config:
      tags: ["PII"]
      elementary:
        timestamp_column: "signup_date"
    tests:
      - elementary.volume_anomalies
```

This test will fail if there are any days (as defined by **signup_date**) where the number of rows exceeds 3 standard deviations above/below the mean.

</Accordion>
<br/>
<Accordion title="Test 2: Returned Orders">
Similar to Test 1, we will use the **volume_anomalies** test to detect an anomalous number of returned orders in a given time period. In this test, however, we will define the timestamp column at the test level - instead of at the model level.
```yaml
  - 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"

````
</Accordion>
<br/>
<Accordion title="Test 3: Dimension Anomalies in the Orders Model">
The **elementary.dimension_anomalies** tests can be used to check for anomalies in the distribution of data in low cardinality fields. First, we will select the **status** column in the Orders model to run this test on:
```yaml
  - name: orders
    description: This table has basic information about orders, as well as some derived facts based on payments
    config:
      tags: ["finance"]

    tests:
      - elementary.dimension_anomalies:
          dimensions:
            - status
````

Next, we will define a timestamp column for determining time buckets:

```yaml
- name: orders
  description: This table has basic information about orders, as well as some derived facts based on payments
  config:
    tags: ["finance"]
    elementary:
      timestamp_column: "order_date"

  tests:
    - elementary.dimension_anomalies:
        dimensions:
          - status
```

This test will gather row count metrics for each value in the **status** column and will fail if the distribution deviates substantially from the mean.

</Accordion>
<br/>
<Accordion title="Test 4: Column Anomalies in the Customers Model">
We will use the **elementary.column_anomalies** test to monitor the count of customers with 0 orders. To do so, we will define a **zero_count** test under **elementary.column_anomalies** for the **number_of_orders** column:
```yaml
      - name: number_of_orders
        description: Count of the number of orders a customer has placed
        tests:
          - elementary.column_anomalies:
              config:
                severity: warn
              tags: ["column_anomalies"]
              column_anomalies:
                - zero_count
              timestamp_column: "signup_date"
```
<Info>
Notice that we already defined the **timestamp_column** at the model level, so we don't have to define it in the test. [This page](/data-tests/elementary-tests-configuration) has in-depth details on test priorities.
</Info>
</Accordion>
<br/>
Copy the text below into your `schema.yml` file to add all of the above tests to our project:
<Accordion title="Final schema.yml file">

```yaml
version: 2

models:
  - name: customers
    description: This table has basic information about a customer, as well as some derived facts based on a customer's orders
    config:
      tags: ["PII"]
      elementary:
        timestamp_column: "signup_date"
    tests:
      - elementary.volume_anomalies

    columns:
      - name: customer_id
        description: This is a unique identifier for a customer

      - name: first_name
        description: Customer's first name. PII.

      - name: last_name
        description: Customer's last name. PII.

      - name: first_order
        description: Date (UTC) of a customer's first order

      - name: most_recent_order
        description: Date (UTC) of a customer's most recent order

      - name: number_of_orders
        description: Count of the number of orders a customer has placed
        tests:
          - elementary.column_anomalies:
              config:
                severity: warn
              tags: ["column_anomalies"]
              column_anomalies:
                - zero_count
              timestamp_column: "signup_date"

      - name: customer_lifetime_value
        description: Total value (AUD) of a customer's orders

      - name: customer_email
        description: Customer's email. PII.

      - name: signup_date
        description: Date (UTC) of a customer's signup to the online shop.

  - name: orders
    description: This table has basic information about orders, as well as some derived facts based on payments
    config:
      tags: ["finance"]
      elementary:
        timestamp_column: "order_date"

    tests:
      - elementary.dimension_anomalies:
          dimensions:
            - status
    columns:
      - name: order_id
        description: This is a unique identifier for an order

      - name: customer_id
        description: Foreign key to the customers table

      - name: order_date
        description: Date (UTC) that the order was placed

      - name: status
        description: '{{ doc("orders_status") }}'

      - name: amount
        description: Total amount (AUD) of the order

      - name: credit_card_amount
        description: Amount of the order (AUD) paid for by credit card

      - name: coupon_amount
        description: Amount of the order (AUD) paid for by coupon

      - name: bank_transfer_amount
        description: Amount of the order (AUD) paid for by bank transfer

      - name: gift_card_amount
        description: Amount of the order (AUD) paid for by gift card

  - 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"

    columns:
      - name: order_id
        description: This is a unique identifier for an order

      - name: customer_id
        description: Foreign key to the customers table

      - name: order_date
        description: Date (UTC) that the order was placed

      - name: status
        description: '{{ doc("orders_status") }}'

      - name: amount
        description: Total amount (AUD) of the order

      - name: credit_card_amount
        description: Amount of the order (AUD) paid for by credit card

      - name: coupon_amount
        description: Amount of the order (AUD) paid for by coupon

      - name: bank_transfer_amount
        description: Amount of the order (AUD) paid for by bank transfer

      - name: gift_card_amount
        description: Amount of the order (AUD) paid for by gift card
```

</Accordion>
<br/>

**You have now added Elementary tests to your project. Now let's see how they are run and visualized.**