refactor(ng-lib): manage HttpClient dependency

[LayZeeDK]

PR Checklist

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• The commit message follows our guidelines: https://github.com/scullyio/scully/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
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PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Other... Please describe:

What is the current behavior?

ComponentsModule.forRoot only provides HttpClient, but not its dependencies.

Pull Requests: #69 #75
Issue Number: #52

What is the new behavior?

Instead of providing only HttpClient, but not its dependencies, we now re-export HttpClientModule in the static forRoot method of ComponentsModule.

I have also added a test suite for the ComponentsModule which exercises injecting HttpClient and its dependencies.

Does this PR introduce a breaking change?

• Yes
• No

Other information

Note that the init schematic currently adds HttpClientModule to the consumers AppModule imports.

Sorry for bringing this up again, but the current implementation only provides HttpClient. I did some digging and discovered that HttpClientModule actually provides quite a few dependencies used by HttpClient at runtime.

How do we want to handle this?

In the new approach of this PR, I simply re-export HttpClientModule in ComponentsModule.forRoot.

Usually, we would just expect the consuming application to inject HttpClientModule. The classes depending on HttpClient (ScullyRoutesService and ScullyContentComponent) would crash at runtime, if HttpClient and its dependencies were not provided by the consuming application.

Is this a better option? Then we can remove the static forRoot method instead. If so, we could probably detect the error early by attempting to inject HttpClient in ComponentsModule's constructor as an optional dependency and throw an error with a helpful message if it could not be resolved.

[claassistantio]

All committers have signed the CLA.

[LayZeeDK]

Alternatives to guard for HttpClient or have transient import of HttpClientModule.
https://gist.github.com/LayZeeDK/d55b22365c87260387273a42f6baa5cc

[LayZeeDK]

Closed because of decision to remove the HttpClient dependency.