Writing test cases

Once you have your components hooked up, you're ready to write some tests.

Basic test structure

Cavy provides describe and it functions to write and group your test cases. The basic structure of your tests will be something like this:

// specs/AppSpec.js

export default function(spec) {

  spec.describe('My feature', function() {
    spec.it('works', async function() {
      await spec.fillIn('Scene.TextInput', 'some string')
      await spec.press('Scene.button');
      await spec.exists('NextScene');
    });
  });
}

You reference your hooked-up components using the string you provided to generateTestHook in the ref assigned to them.

Setup

You can use beforeEach to call a function before each test runs. The beforeEach function will be called after AsyncStorage is cleared but before the app re-renders and the test is run. So the order of actions for each test execution is:

1. AsyncStorage is cleared (if the clearAsyncStorage prop is set to true in Tester)
2. The beforeEach function is called (if defined for this test)
3. The app is re-rendered
4. The test is run

// specs/AppSpec.js

export default function(spec) {

  spec.beforeEach(function() {
    // This will run before each test in this spec file.
  });

  spec.describe('My feature', function() {
    spec.it('works', async function() {
      await spec.fillIn('Scene.TextInput', 'some string')
      await spec.press('Scene.button');
      await spec.exists('NextScene');
    });
  });
}

See also

• beforeEach reference
• Tester component API

The DSL

Cavy gives you a set of functions which you can use when writing your tests to do the following:

• Querying
• Interacting through touch
• Inputting text
• Finding elements
• Pausing

Below is an overview of what you can do with Cavy. See the API for a more comprehensive reference.

Querying

Cavy gives you functions to query the existence, or absence, of elements in your app:

await spec.exists('MenuItem');
await spec.notExists('OtherMenuItem');

Interacting through touch

You can interact with elements that respond to onPress, such as Buttons or other "Touchable" components:

await spec.press('Button');

Inputting text

You can enter text into TextInput components:

await spec.fillIn('Input');

Finding elements

You can find specific elements in order to interact with them:

const link = await spec.findComponent('Scene.MyLink');

Pausing

Cavy lets you pause between interactions, which can be useful if you need to wait for a response before continuing:

 await spec.pause(3000);

Reference

• Helpers API