> ## Documentation Index
> Fetch the complete documentation index at: https://docs.metlo.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Writing a Test

You can write tests for your endpoints in a simple YAML based DSL. These tests
can be run using either the CLI or inside Metlo's UI.

### Creating a New Test

To create a new test make a new yaml file (i.e. `user_endpoint_test.yaml`).

#### 1. Define Metadata

The first step is to define some metadata for your test:

```yaml YAML theme={null}
id: www-example-com-user-test

meta:
  name: www.example.com/user Test Auth
  severity: LOW
  tags:
    - BROKEN_AUTHENTICATION
```

* **id** - A unique id for your test. This can be any string that matches the
  pattern `[A-Za-z0-9-_]+`
* **meta.name \[optional]** - A name for your test
* **meta.severity \[optional]** - `LOW | MEDIUM | HIGH | CRITICAL`
* **meta.tags \[optional]** - A list of tags for your test

#### 2. Add your Test

A test is a set of steps, where each step has an HTTP request and a set of
assertions. Heres an example of a test that sends a `GET` request to
[https://example.com](https://example.com) and verifies that the response status
is `200` and the content length header is `"648"`.

*All the fields in the `resp` object are documented
[here](/advanced-tests#resp-object)*

```yaml YAML theme={null}
test:
  - request:
      method: GET
      url: https://example.com
    assert:
      - key: resp.status
        value: 200
      - key: resp.headers['content-length']
        value: "648"
```

You can also specify query params, headers and data for a request.

```yaml YAML theme={null}
test:
  - request:
      method: POST
      url: https://test-payment-processor.metlo.com/user/billing
      headers:
        - name: Content-Type
          value: application/json
        - name: Authorization
          value: ...
      data: |-
        {
            "ccn": "...",
            "cc_exp": "...",
            "cc_code": "..."
        }
    assert:
      - key: resp.status
        value: 200
```

A complete test might look something like this:

```yaml YAML theme={null}
id: test-payment-processor-metlo.com-user-billing

meta:
  name: test-payment-processor.metlo.com/user/billing Test Auth
  severity: CRITICAL
  tags:
    - BROKEN_AUTHENTICATION

test:
  - request:
      method: POST
      url: https://test-payment-processor.metlo.com/user/billing
      headers:
        - name: Content-Type
          value: application/json
        - name: Authorization
          value: ...
      data: |-
        { "ccn": "...", "cc_exp": "...", "cc_code": "..." }
    assert:
      - key: resp.status
        value: 200
  - request:
      method: POST
      url: https://test-payment-processor.metlo.com/user/billing
      headers:
        - name: Content-Type
          value: application/json
      data: |-
        { "ccn": "...", "cc_exp": "...", "cc_code": "..." }
    assert:
      - key: resp.status
        value:
          - 401
          - 403
```

### Run a Test

You can run your test with the Metlo CLI:

```bash Bash theme={null}
$ metlo test run user_endpoint_test.yaml
Running test at path "user_endpoint_test.yaml":
✔ Done loading test...
✔ Done running test...
All Tests Succeeded!
```

### Making a Test in Metlo's UI

You can make a test in Metlo's UI on the tests tab on the endpoint page.

<img src="https://mintcdn.com/metlo/bLaSw1tiF6Fz1nHn/images/31c8af8-136efa1-Screenshot_2022-12-26_at_7.14.04_PM.png?fit=max&auto=format&n=bLaSw1tiF6Fz1nHn&q=85&s=2a89046349e7bd6f9c052b5dcba4d64c" alt="3808" width="3808" height="2414" data-path="images/31c8af8-136efa1-Screenshot_2022-12-26_at_7.14.04_PM.png" />