Skip to content

Assertion library for unit testing JS generators. Works well with redux-saga. Allows snapshot testing.

License

Notifications You must be signed in to change notification settings

jimbol/expect-gen

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 

History

39 Commits
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Repository files navigation

Expect Gen

As in "expect generator...". An assertion / snapshot library for testing iterators and generators. It was designed for, and works particularly well with, redux-saga but can be used for anything that uses generators.

Example

function* myEffect(fakeAction) {
  const fooIds = yield select(fooIds);
  yield put(foosLoading());
  const results = yield call(apiFetch, options);
}

import expectGen from 'expect-gen';

it('runs effect with fakeFooIds and fakeResults', () => {
  expectGen(myEffect, fakeAction)
    // asserts step yields first `select(fooIds)`
    .yields(
      select(fooIds),
      // `fakeFooIds` gets pass into the following `next`
      fakeFooIds
    )
    .yields(
      put(foosLoading())
    )
    .yields(
      call(apiFetch, options),
      fakeResults
    )
    .finishes()
    .run();
});

it('runs effect with fakeFooIds and fakeResults', () => {
  const snapshot = expectGen(myEffect, fakeAction)
    // Doesn't run assertion for `next`
    .next(fakeFooIds)
    .next()
    .yields(
      call(apiFetch, options),
      fakeResults
    )
    .finishes()
    .toJSON();

  expect(snapshot).toMatchSnapshot();
});

API

expectGen

expectGen(generator, [...args])

  • Calls the first argument with the rest of the arguments
  • Returns instance of StepManager

StepManager

expectGen returns an instance StepManager. It gives us a set of chainable methods:

yields

expectGen(generator, [...args])
  .yields(expectedValue, [result])
  • Runs an assertion that iterator will yield the expectedValue
  • Passes result into generator's next method
  • Returns same instance StepManager

next

expectGen(generator, [...args])
  .next([result])
  • Passes result into generator's next method
  • Makes no assertion
  • Returns same instance StepManager

throws

expectGen(generator, [...args])
  .throws(error)
  • Throws error into generator
  • Checks that iterator throws an uncaught exception
  • Returns same instance StepManager

catches

expectGen(generator, [...args])
  .catches(error, [expectedValue])
  • Throws error into generator
  • Runs an assertion that thrown iterator will yield the expectedValue
  • Returns same instance StepManager

catchesAndFinishes

expectGen(generator, [...args])
  .catchesAndFinishes(error, [result])
  • Throws error into generator
  • Asserts that generator finishes with result
  • Returns same instance StepManager

finishes

expectGen(generator, [...args])
  ...
  .finishes([result])
  • Asserts that generator finishes with result
  • Returns same instance StepManager

run

expectGen(generator, [...args])
  ...
  .run()
  • Executes all assertions
  • Returns results of all generator steps as an array

toJSON

expectGen(generator, [...args])
  ...
  .toJSON()
  • Convert results from run() into a JSON object

Roadmap

Expect Gen is heading towards v1. The following items still need to go in before then. Please open issues for other v1 requirements you find.

v1.0.0

Previous Version

Expect Gen is a second generation version of generator-test-runner. Many of the concepts used here originated there.

About

Assertion library for unit testing JS generators. Works well with redux-saga. Allows snapshot testing.

Topics

Resources

License

Stars

Watchers

Forks

Releases

No releases published

Packages

No packages published

Contributors 4

  •  
  •  
  •  
  •