object destructuring defaults reported as uncovered branch

Do you want to request a feature or report a bug? bug

What is the current behavior? The coverage reporter reports that the default values I assign in object destructuring are “not covered branches”.

If the current behavior is a bug, please provide the steps to reproduce and either a repl.it demo through https://repl.it/languages/jest or a minimal repository on GitHub that we can yarn install and yarn test. Simply create a code that uses object destructuring defaults and check out the coverage report:

const {
  foo = 'bar'
} = this.props;

The = 'bar' segment will be considered “uncovered” by the coverage reporter.

What is the expected behavior?

The coverage reported will ignore it, since there’s nothing to test there.

Please provide your exact Jest configuration and mention your Jest, node, yarn/npm version and operating system.

create-react-app config reproduces the problem just fine.

Moved from https://github.com/facebook/jest/issues/3091

[mehmetnyarar]

I encounter this issue. My fn:

export const getConfig = (env?: EnvVars, phase?: string): EnvConfig => {
  const {
    KEY1 = 'default',
    KEY2 = 'default',
    KEY3,
    KEY4,
    KEY5 = 10
  } = env || process.env

  // ...

  return config
}

My tests include:

• getConfig() without initial env (defaults to process.env)
• getConfig({}) empty env
• getConfig({ KEY1: 'value', KEY2: 'value', KEY3: 'value', KEY4: undefined, KEY5: 20 }) with initial env

yet the de-structuring is not covered.

Is there any solution to this?

Putting /* istanbul ignore next */ comment before any de-structuring is not really a solution.

[akhileshwarr]

I faced same issue while destructuring props, culprit was react defaultProps, and code will never reach destructuring defaults.

const {  withCancel = false } = props;  // destructuring defaults are  not reachable

 ContentFooter.defaultProps = { // react defaultProps will set the value before it reaches destructuring defaults
  withCancel: false
};