jasmine-stray-timers

Jasmine test helper for detecting setTimeout and setInterval usage outside of test boundaries.

Requires jasmine.

Install

$ npm install --save-dev jasmine-stray-timers

Usage

In karma:

// karma.conf.js
module.exports = function(config) {
  config.set({
    frameworks: ['jasmine'],
 
    files: [
      // ...,
      require.resolve('jasmine-stray-timers'),
      // ...
    ],
  });
};

Ignoring stray timers in a test

Stray timers can be ignored in a single test or in a suite by calling this._ignoreStrayTimers in the jasmine test context.

export function foo(a) {
  setTimeout(function() {
    // do something async
  }, 100);
  return a + 1;
}
 
describe('foo', function() {
  it('bar', function() {
    this._ignoreStrayTimers();
 
    expect(bar()).toEqual(2);
  });
});

Only print warning on stray timers in a test

Stray timers can be ignored, and an error can be printed in a single test or in a suite by calling this._onlyWarnOnStrayTimers in the jasmine test context.

export function foo(a) {
  setTimeout(function() {
    // do something async
  }, 100);
  return a + 1;
}
 
describe('foo', function() {
  it('bar', function() {
    this._onlyWarnOnStrayTimers();
 
    expect(bar()).toEqual(2);
  });
});

Output

If test code executed a timer and didn't wait for it to resolve before ending the test, it will throw an error.

// src.js
export function foo(a) {
  setTimeout(function() {
    // do something async
  }, 100);
  return a + 1;
}
 
export function bar() {
  return foo(1);
}

// test.js
import { bar } from './src';
 
describe('foo', function() {
  it('bar', function() {
    expect(bar()).toEqual(2);
  });
});

PhantomJS 2.1.1 (Mac OS X 0.0.0) foo bar FAILED
       Error: Stray "setTimeout" call was executed outside the test constraints (line 68)
       localSetTimeout
       foo
       bar
       loaded@http://localhost:9876/context.js:151:17
PhantomJS 2.1.1 (Mac OS X 0.0.0): Executed 1 of 1 (1 FAILED) (skipped 10) ERROR (0.005 secs / 0.001 secs)

Caveat

Due to the nature of how async javascript execution works, if a timer is set up within another async operation (eg. Promise), this library cannot reliably determine the exact test that triggered the timer.

In this case, the error will be triggered in an subsequent test in which the async operation resolved.

// src.js
export function foo(a) {
  window.fetch('some url')
    .then(function() {
      setTimeout(function() {
        // do something async
      }, 100);
    });
  return a + 1;
}

// test.js
import './src';
 
describe('foo', function() {
  it('test 1', function() {
    expect(foo(1)).toEqual(2);
  });
 
  it('test 2', function() {
    expect(2).toEqual(2);
  });
});

License

Apache-2.0