03-writing-tests-and-scripts

Writing tests and scripts

Table of Contents

• First test
  • Notes on writing tests
• Testing an API
• Testing an API - Writing more tests
• Recap: Path parameters vs query parameters
• Assignment notes

First test

Tests in Postman run only after a request is completed.

pm.test('Status code is 200', () => {
  pm.response.to.have.status(200)
})

This is added to the Tests tab of the request builder.

Once a request is made and responds, the result of your tests can be evaluated in the response section under Tests.

If a test is passing without having failed before... test that it does fail! We don't want false positives leading us astray.

Notes on writing tests

• tests always start with pm.test
• tests are run in a non-blocking in case of developer errors
• each test can contain multiple assertions
• pm.response is Postman's response assertion API for making assertions on the response specifically (status, headers, body, etc)

Testing an API

We'll use Trello as a basis for our API tests.

We'll need to get an API key, which identifies the application (Postman, in this case) making requests to Trello, and get a token, which is what identifies the specific user: trello.com/app-key

• Method: POST

• Address: https://api.trello.com/1/boards/

• Query Params:

    name: 'My board',
    key: [My Trello API key]
    token: [My Trello token]
  

This creates a board with Trello's default lists. To disable the default lists one can provide a query param of defaultList=false.

Testing an API - Writing more tests

When creating a Trello board, it's not good enough to only test that the status code in the response is correct. We need to evaluate the data returned in the response is correct, too.

To do this, we need to do a few things:

pm.test('sets the correct board name', () => {
  // get the json data from the response
  const jsonData = pm.response.json()

  pm.expect(jsonData.name).to.eql('My board name')
})

Check that the test fails by adding a name that is incorrect.

We can expand on these tests:

pm.test('sets the correct board name', () => {
  // get the json data from the response
  const jsonData = pm.response.json()

  pm.expect(jsonData.name).to.eql('My board name')
  pm.expect(jsonData.closed).to.eql(false)
  pm.expect(jsonData.prefs.permissionLevel).to.eql('private')
})

Recap: Path parameters vs query parameters

When using the Params section of the request builder, path variables cannot be toggled, as this changes the path, whereas query parameters being toggled don't change the path.

Assignment notes

It's tedious to add query parameters with hard-coded values to multiple requests, so to make this easier to manage, we can save parameters to global variables:

1. Copy the key value in the previous request's query parameters
2. Click the eye in the top right, and edit globals
3. Add a trelloKey and paste your value
4. Do the same for your Trello token
5. In the Params tab replace the hardcoded values for key and token with {{trelloKey}} and {{trelloToken}}

Hovering over the global variables will show what is stored.

To quickly copy query parameters to other requests in Postman, select Bulk edit and copy what you want, instead of manually creating individual params in each request.