prints independent operation name

[vasilich6107]

Hi @budde377

this PR adds printing of an independent operation name for the cases when we do not use graphql and graphql_flutter clients.

For example when we use https://github.com/artflutter/graphql_flutter_bloc and want to pass operationName to WatchQueryOptions
https://github.com/artflutter/graphql_flutter_bloc/blob/master/test/query_bloc_test.dart#L26

I see that there is a class WatchOptions$Query but it is being generated only in case if we add client generation.

[vasilich6107]

One more thing that we probably could try is...

[vasilich6107]

This is it

Added an ability to access the operation name via static variable operationNameDefinition which is useful in tests for mocking purposes

smth like

if(oprationName == WatchQueryOptions.operationNameDefinition) {
  // then return some mock
}

[vasilich6107]

If this approach makes sense for you I will finish the tests

[budde377]

Thanks for suggesting this @vasilich6107! Some minor suggestions:

I think it would make sense to store the operation name next to the document node, e.g.

const documentNodeMutationX = ...
const operantionNameMutationX = ...

That way you will always generate the operation name regardless of the client being present.

You can still expose it as you suggest on the options.

I would be nice if we are consistent on exposing it across the options, also the watch-options.

A protip for getting the tests updated would be to

1. Update the packages/graphql_codegen/test/builder_test.dart file to make the test override the files.
2. Run tests.
3. Review the new files.
4. Change back the lines above.

[vasilich6107]

Hi @budde377
Could you check the fixes