chore: Simplifies Unknown detection (#3137)

* check that they behave the same

* remove HasUnknowns

* keep tests

Author: lantoli

internal/common/schemafunc/plan_modifier_state_for_unknown_test.go

@@ -42,6 +42,7 @@ type hasUnknownsPanicMissingMethod struct {
 	Field missingMethodType
 }
 
+// TestHasUnknown is kept even if HasUnknowns is not used so we can test isUnknown that is also used in CopyFromUnknown
 func TestHasUnknown(t *testing.T) {
 	tests := map[string]struct {
 		input        any

internal/service/advancedclustertpf/resource.go

@@ -16,7 +16,6 @@ import (
 
 	"github.com/mongodb/terraform-provider-mongodbatlas/internal/common/constant"
 	"github.com/mongodb/terraform-provider-mongodbatlas/internal/common/conversion"
-	"github.com/mongodb/terraform-provider-mongodbatlas/internal/common/schemafunc"
 	"github.com/mongodb/terraform-provider-mongodbatlas/internal/common/update"
 	"github.com/mongodb/terraform-provider-mongodbatlas/internal/config"
 	"github.com/mongodb/terraform-provider-mongodbatlas/internal/service/flexcluster"
@@ -99,7 +98,7 @@ type rs struct {
 // 1. UseStateForUnknown always copies the state for unknown values. However, that leads to `Error: Provider produced inconsistent result after apply` in some cases (see implementation below).
 // 2. Adding the different UseStateForUnknown is very verbose.
 func (r *rs) ModifyPlan(ctx context.Context, req resource.ModifyPlanRequest, resp *resource.ModifyPlanResponse) {
-	if req.Plan.Raw.IsNull() || req.State.Raw.IsNull() { // Return early unless it is an Update
+	if req.State.Raw.IsNull() || req.Plan.Raw.IsNull() || req.Plan.Raw.IsFullyKnown() { // Return early unless it is an Update
 		return
 	}
 	var plan, state TFModel
@@ -109,10 +108,8 @@ func (r *rs) ModifyPlan(ctx context.Context, req resource.ModifyPlanRequest, res
 	if diags.HasError() {
 		return
 	}
-	if !schemafunc.HasUnknowns(&plan) { // Don't do anything if there are no unknowns, this happens in Read
-		return
-	}
-	useStateForUnknowns(ctx, diags, &state, &plan) // Do only for Update
+
+	useStateForUnknowns(ctx, diags, &state, &plan)
 	if diags.HasError() {
 		return
 	}