Professor Chaos

Professor Chaos is a tool to help unexpectently break your programs to see how they handle errors.

npm install professor-chaos

Usage

Professor Chaos has two methods of destruction: time and call based error triggers. These errors are instances of ChaosError as to be more easily identifiable.

var pc = require('professor-chaos');

/*
  Calling `timer` will set an error to be thrown within a given timeframe.
*/
var clock = pc.timer(1000);

/*
  Calling `fault` creates a break point where an error will be thrown/handled
  within a random number of `hasError` calls between a given interval.
*/
var fault = pc.fault(10);

function handler(value1, value2, callback) {
  if(fault.hasError()) {
    fault.error('Random handler error', callback);
  } else {
    // do something
  }
}

Methods

timer

/*
timer(max: number): number
timer(min: number, max: number): number
*/

Accepts a required maximum time max to wait to throw an error. Accepts an optional minimum time min to wait to throw an error which defaults to zero. Returns the setTimeout ID to allow you to use clearTimeout if necessary.

This function will asynchronously throw an error some time between min and max.

fault

/*
fault(max: number): Fault
fault(min: number, max: number): Fault
*/

Accepts a required maximum max to count to until throwing an error. Accepts an optional minimum min to count to until throwing an error which defaults to zero. Returns a Fault object.

This method creates a Fault object to be used inside the scope of a given function to create an error to then either throw or pass to a provided callback.

/*
interface Fault {
  hasError(): boolean
  error(): void
  error(message: string): void
  error(callback: (error) => any): void
  error(message: string, callback: (error) => any): void
}
*/

The hasError() method returns whether or not an error if ready to be thrown. The hasError() method is managed internally to see how often it is called and will signal error() to throw somewhere within the given min and max parameters.

The error() method accepts an optional error message which by default is awesome. The error() method accepts an optional callback function which receives the error that would otherwise be thrown if no callback is provided.

Note: error() will continue to create random errors after the first and each will be just as unpredictable as the last.

Contributing

We can always have more tests: if you find a bug, create an issue or be fabulous and fix the problem and write the tests up yourself in a coherent pull request.

Run tests with the npm test command.

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