Enforce valid describe() callback (valid-describe)

Using an improper describe() callback function can lead to unexpected test errors.

Rule Details

This rule validates that the second parameter of a describe() function is a callback function. This callback function:

• should not be async
• should not contain any parameters
• should not contain any return statements

The following describe function aliases are also validated:

• describe
• describe.only
• describe.skip
• fdescribe
• xdescribe

The following patterns are considered warnings:

// Async callback functions are not allowed
describe('myFunction()', async () => {
  // ...
});

// Callback function parameters are not allowed
describe('myFunction()', done => {
  // ...
});

//
describe('myFunction', () => {
  // No return statements are allowed in block of a callback function
  return Promise.resolve().then(() => {
    it('breaks', () => {
      throw new Error('Fail');
    });
  });
});

The following patterns are not considered warnings:

describe('myFunction()', () => {
  it('returns a truthy value', () => {
    expect(myFunction()).toBeTruthy();
  });
});