json-output: Add change reasons to explain deletes

[alisdair]

The extra feedback information for why resource instance deletion is planned is now included in the streaming JSON UI output.

We also add an explicit case for no-op actions to switch statements in this package to ensure exhaustiveness, for future linting.

[apparentlymart]

Oh, interesting! I updated what is essentially the same thing over in the jsonplan package.

terraform/internal/command/jsonplan/plan.go

Lines 336 to 357 in c8cd0b1

	switch rc.ActionReason {
	case plans.ResourceInstanceChangeNoReason:
	r.ActionReason = "" // will be omitted in output
	case plans.ResourceInstanceReplaceBecauseCannotUpdate:
	r.ActionReason = "replace_because_cannot_update"
	case plans.ResourceInstanceReplaceBecauseTainted:
	r.ActionReason = "replace_because_tainted"
	case plans.ResourceInstanceReplaceByRequest:
	r.ActionReason = "replace_by_request"
	case plans.ResourceInstanceDeleteBecauseNoResourceConfig:
	r.ActionReason = "delete_because_no_resource_config"
	case plans.ResourceInstanceDeleteBecauseWrongRepetition:
	r.ActionReason = "delete_because_wrong_repetition"
	case plans.ResourceInstanceDeleteBecauseCountIndex:
	r.ActionReason = "delete_because_count_index"
	case plans.ResourceInstanceDeleteBecauseEachKey:
	r.ActionReason = "delete_because_each_key"
	case plans.ResourceInstanceDeleteBecauseNoModule:
	r.ActionReason = "delete_because_no_module"
	default:
	return nil, fmt.Errorf("resource %s has an unsupported action reason %s", r.Address, rc.ActionReason)
	}

I didn't realize we had this in two places... updating them both to be in sync is a good immediate fix here, so let's indeed go ahead and merge this, but I think it'd also be good to think about how we can unify these two codepaths so that we only have to update one place and so that we don't risk them getting out of sync and using different strings to represent each case. 🤔

(Thankfully, it seems like you picked string values here that match what I added in the other place, so this'll be back to consistency for now.)

[alisdair]

Thankfully, it seems like you picked string values here that match what I added in the other place, so this'll be back to consistency for now.

Unfortunately for the previous set of action reasons I chose different values for the JSON string representations (not realizing that they were in the JSON plan, I guess?). So I think we are stuck with the divergence 😢

[github-actions]

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