Friendlier waitFor errors

[haroldtreen]

First off - this library has been a huge help, so thanks for sharing!

Current Behavior:

waitFor is not very user friendly in failure cases.

It you waitFor an event that is never fired, the test suite will just hang until a timeout kicks in.

This is a slow way to detect a failure.

Expected Behavior:

It would be awesome if redux-saga-tester could detect that a saga had run to completion without emitting the desired action.

await sagaTester.waitFor(actions.FAKE_ACTION);

// Fail: actions.FAKE_ACTION was never dispatched

I haven't dug into the saga internals too much, so not sure what the implementation would look like. If you have an idea and can point me in the direction, I'd be happy to open a PR.

Thanks!

[peterox]

I monkey patch SagaTester to do exactly that

SagaTester.prototype.myWaitFor = function(timeout, actionType, futureOnly) {
  function doTimeout(timeout) {
    return new Promise(function(resolve, reject) {
      setTimeout(reject, timeout - 100, `Timed out waiting for action ${actionType} to be dispatched from saga`);
    });
  }

  return Promise.race([doTimeout(timeout), this.waitFor(actionType, futureOnly)]);
};

You need to pass in the timeout value but it works well.
Example:

it('failed - form error', async function () {
      sagaTester.dispatch(sendPasswordResetEmail('test@example.com'));
      await sagaTester.myWaitFor(2000, sendPasswordResetEmailFailed().type);
      expect(sagaTester.getCalledActions()).to.deep.include(...);
    });
});

[haroldtreen]

The error message is definitely nicer that way 👍 . It's still time based though.

It would be awesome if you could detect the saga had run to completion and never dispatched that action - then explode.

[ghost]

I'm not sure if that would be possible as the original error you saw was from the testing framework (in your case Jasmine), not SagaTester. Once jasmine times out there is no way to continue with the test.

The caveat to my patch is that the timeout value must be <= to the testing frameworks timeout.

When I was using mocha I was calling timeout() to get that, but as the is no equivalent in jasmine I now just hard code a value of 2 seconds

[haroldtreen]

The test isn't failing because code is taking too long to run, so the timeout message is irrelevant.
The test is failing because waitFor can accept non-existent actions and will never return.

I would like waitFor to detect that the saga is complete and return an error stating that the action was never detected.

[mzedeler]

I have a similar problem - I am looking for two different actions, let's call them openDone and openError. If I receive openDone, the test succeds and if I get openError, the test fails.

I propose that we extend the api of the saga tester like this:

• waitFor accepts multiple actions to wait for.
• We add a more generic wait that just returns the first available action.

I don't mind adding the above if someone with access can approve a PR.

[mzedeler]

Ping @3LOK.

[haroldtreen]

@mzedeler Not sure how much our problems align, but I'm going to open a PR for the fix I was proposing 👍 .

[haroldtreen]

PR opened @3LOK 👍

#43

[mzedeler]

I'm sure it is a different thing, but do go ahead, @haroldtreen :-)

[3LOK]

@haroldtreen's PR merged.
@mzedeler - since waitFor returns a promise, can't you use Promise.race or Promise.all for your use case? or am I missing something?

[haroldtreen]

Yay! Well my PR addressed the original reason I opened this issue. So fixed!

I'll close and let others open another if there's any lingering concerns. 👍

[tuzmusic]

@peterox I'm getting funny behavior with your monkeypatch:

it("returns an error for an invalid username", async () => {
    sagaStore.dispatch(login(creds.badUser));
    await sagaStore.myWaitFor(2000, "LOGIN_FAILURE");
    expect(sagaStore.getCalledActions()).toEqual([
      actions.startSuccess,
      actions.loginBadUser
    ]);
  });

I don't get an error message. Of any kind! Just Test run was interrupted.

 ● integration › returns an error for an invalid username

      233 |   });
      234 | 
    > 235 |   it("returns an error for an invalid username", async () => {
          |   ^
      236 |     sagaStore.dispatch(login(creds.badUser));
      237 |     await sagaStore.wait(2000, "LOGIN_FAILURE");

      at Env.it (node_modules/@jest/core/node_modules/jest-jasmine2/build/jasmineAsyncInstall.js:91:24)
      at Suite.it (tests/userLogin-saga.test.js:235:3)
      at Object.fdescribe (tests/userLogin-saga.test.js:220:1)

Test Suites: 1 failed, 1 total
Tests:       1 failed, 18 skipped, 1 passed, 20 total
Snapshots:   0 total
Time:        9.723s
Test run was interrupted.

This is a test that should fail (I've yet to implement login failure correctly), and I've also implemented your function in a passing test, so it is working. Am I missing something?