add nop store

[peczenyj]

Hello

In some scenarios it is interesting add an object that does nothing (for testing, debug, etc)

for instance, imagine I may use one of few different implementations of govk.Store and I decide it based on configuration using some strategy pattern. To test the application without the govk.Store I had two options:

1. use a nil store and add several if store != nil {... } around the code, or
2. I had to implement a nop interface by myself

not anymore!

This also perform the validation of key / value like a regular gokv.Store does, to avoid break compatibility.

If you want, I can add an option to disable this validation

Enjoy

[philippgille]

Hi, thanks a lot! I'll have a look on Tuesday.

[philippgille]

Thank you very much for your contribution!

Two comments, but not blockers.

[philippgille]

Not a blocker, but checking all other *_test.go files in this repo, they use either "Expected an error" or "An error was expected". The exact phrasing doesn't matter, but I'd suggest uppercase and past tense for consistency, e.g.

Suggested change

	t.Error("expect error, got nil")
	t.Error("Expected error, got nil")

Errors are usually lowercase as they can be chained in a log message (e.g. "couldn't x: failed to y: ...", but here it's a log message and not an error that might be chained, where I like the differentiation.

Again, totally not a blocker though.

[philippgille]

Thanks for the change 💪