feat: Blocking provider mutator

[znonthedev]

This PR

Adds setProviderAndWait method in the API that will set the provider synchronously

• adds this new feature

Related Issues

Fixes #240

Follow-up Tasks

add test scenarios
update readme

[znonthedev]

Hi @toddbaert, could you please review this PR? I am very new to Go and not sure if this implementation is correct. I will refactor it and keep it DRY if the current implementation meets the expectations outlined in the issue. Thanks in advance.

[toddbaert]

Thank you @znonthedev !

I will review, and also add some reviewers who are more experienced with Go than me! Many people are on holiday however, so it may take a few days to get some approvals. Your patience is appreciated! 🙏

[codecov]

Codecov Report

Attention: 29 lines in your changes are missing coverage. Please review.

Comparison is base (95f592a) 81.61% compared to head (2d95374) 79.83%.

Files	Patch %	Lines
openfeature/api.go	61.97%	23 Missing and 4 partials ⚠️
openfeature/openfeature.go	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #244      +/-   ##
==========================================
- Coverage   81.61%   79.83%   -1.78%     
==========================================
  Files          10       10              
  Lines        1142     1195      +53     
==========================================
+ Hits          932      954      +22     
- Misses        192      220      +28     
- Partials       18       21       +3     

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[znonthedev]

I have updated the PR based on the comments. I have added two test cases also. I am not sure on the test cases. Do I need to add more test cases or change the current ones

[toddbaert]

We need to add an equivalent function for setting a named provider and waiting (see here).

[toddbaert]

@bacherfl when you get a moment, could you take a look at this as well?

[znonthedev]

We need to add an equivalent function for setting a named provider and waiting (see here).

Certainly, @toddbaert. I had the same thought. I will incorporate the necessary changes into the PR

[toddbaert]

It might be nice to add a test that works like this:

• set a provider which is ready after 1s (has an init function that returns after 1s)
• returns a valid flag value after that time only
• returns an error before 1s

This is consistent with how we'd expect many providers to work. Maybe you could add some options to NewMockFeatureProvider that would support this?

[znonthedev]

okay, I got the idea. I'll give it a try, but since I'm new to Go, it might take me some time 😇 .

[bacherfl]

I just had a look at the test, and to make sure the Init function actually gets called, you will need to have a type that consolidates a MockFeatureProvider and MockStateHandler - otherwise the check here will fail and the function will proceed without calling the Init function of the provider.

Since gomock, which we use for creating the mocks seems to not support the generation of a type that implements multiple interfaces, i believe the simplest way to get a struct that implements both the FeatureProvider and the StateHandler interfaces is to consolidate them into a single struct, such as follows:

type mockProviderAndStateHandler struct {
	*MockFeatureProvider
	*MockStateHandler
}

This type should be defined in the client_test.go file, and can then be used to pass it to the SetProviderAndWait function, such as in the following example:

...
		mockProvider.EXPECT().Metadata().AnyTimes()
		mockProvider.EXPECT().Hooks().AnyTimes()
		mockProvider.EXPECT().IntEvaluation(context.Background(), flagKey, defaultValue, flatCtx).
			Return(IntResolutionDetail{
				Value: 0,
				ProviderResolutionDetail: ProviderResolutionDetail{
					ResolutionError: NewGeneralResolutionError("test"),
				},
			}).Times(2)

		mockStateHandler := NewMockStateHandler(ctrl)

                // TODO add the desired behavior for the Init function of the MockStateHandler

		o := & mockProviderAndStateHandler{
			MockFeatureProvider: mockProvider,
			MockStateHandler:    mockStateHandler,
		}

		err := SetProviderAndWait(o)
...

[Kavindu-Dodan]

please remove this file

[Kavindu-Dodan]

You may refactor to combine initNewAndShutdownOldAsync & initNewAndShutdownOldSync as they perform similar set of operations with only difference being sync vs async.

[bacherfl]

Nitpick: to stay consistent with the naming i would suggest to call this function setProviderSync

[toddbaert]

Agreed. The spec doesn't dictate function names. I think your suggestion makes sense here.

[bacherfl]

i think this comment does not apply for this function anymore (since this is the blocking variant) and can be removed

[Kavindu-Dodan]

@znonthedev are you planning to complete this contribution soon ? There are pending changes in some providers which require this feature.

[toddbaert]

Closed with #251