Allow implicit ResourceListProcessorFunc

[mozesl-nokia]

Currently, if you want to pass a function to AsMain, even if it has the correct ResourceListProcessorFunc signature, it will still fail the casting. Thus, it has to be explicitly wrapped.

With this PR, you can now just pass the function pointer or an anonymous/lambda function.

No AI was used in the creation of this PR.

[Copilot]

Pull request overview

This PR updates the Go KRM Functions SDK’s AsMain entrypoint to accept more natural processor inputs (including plain functions matching the ResourceListProcessorFunc signature) without requiring explicit wrapping, and adds tests to cover the newly supported input forms.

Changes:

• Extend AsMain to accept any ResourceListProcessor implementation and raw func(*ResourceList) (bool, error) values.
• Remove redundant processor type-casting logic from Run.
• Add a new unit test covering multiple AsMain input types (processor struct, implicit/explicit func, runner processor, anonymous func).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
go/fn/run.go	Broaden AsMain input handling and simplify Run by removing prior type switching.
go/fn/run_test.go	Add coverage for the expanded AsMain accepted input types.

Comments suppressed due to low confidence (1)

go/fn/run.go:216

• Run no longer validates the processor argument, so calling Run(nil, ...) will now panic when p.Process is invoked. Since Run is a public API, it should fail fast with a regular error for a nil processor (maintains the previous behavior of returning an error instead of panicking).

func Run(p ResourceListProcessor, input []byte) ([]byte, error) {
	rl, err := ParseResourceList(input)
	if err != nil {
		return nil, err
	}
	success, fnErr := p.Process(rl)
	out, yamlErr := rl.ToYAML()

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