Feature Request: Add `IfNotExistsAction` to Machinery

[camilamacedo86]

What is missing

We want to skip missing files during scaffolding without failing.

Right now, if a file doesn’t exist (like a test file), Scaffold.Execute() fails. But some files (like test/e2e/webhook_test.go) are optional, and we want to ignore them safely.

---

What do we need

We need something like

type IfNotExistsAction int

const (
	IgnoreFile IfNotExistsAction = iota
)

type File struct {
	Path              string
	Contents          string
	IfExistsAction    IfExistsAction
	IfNotExistsAction IfNotExistsAction
}

type Inserter interface {
	...
	GetIfNotExistsAction() IfNotExistsAction
}

type IfNotExistsActionMixin struct {
	IfNotExistsAction IfNotExistsAction
}

func (m IfNotExistsActionMixin) GetIfNotExistsAction() IfNotExistsAction {
	return m.IfNotExistsAction
}

AND

m, err := s.loadPreviousModel(i, models)
if err != nil {
	if i.GetIfNotExistsAction() == IgnoreFile && os.IsNotExist(err) {
		log.Infof("Skipping missing file: %s", i.GetPath())
		return nil
	}
	return fmt.Errorf("failed to load previous model for %s: %w", i.GetPath(), err)
}

So we can configure specific templates like:

type WebhookTestUpdater struct {
	machinery.MarkerUpdaterMixin
	machinery.IfNotExistsActionMixin
}

Such as we have:

	if f.Force {
		f.IfExistsAction = machinery.OverwriteFile
	}

By default should fail unless we configure / write to IfNotExistAction ignore files

[aman4433]

/assign