Ephemeral write only attributes (#3171)

Signed-off-by: Andrei Ciobanu <andrei.ciobanu@opentofu.org>
Signed-off-by: Christian Mesh <christianmesh1@gmail.com>

internal/command/jsonformat/computed/renderers/testing.go

@@ -6,6 +6,8 @@
 package renderers
 
 import (
+	"maps"
+	"slices"
 	"sort"
 	"testing"
 
@@ -42,6 +44,18 @@ func ValidatePrimitive(before, after interface{}, action plans.Action, replace b
 	}
 }
 
+func ValidateWriteOnly(action plans.Action, replace bool) ValidateDiffFunction {
+	return func(t *testing.T, diff computed.Diff) {
+		validateDiff(t, diff, action, replace)
+
+		_, ok := diff.Renderer.(*writeOnlyRenderer)
+		if !ok {
+			t.Errorf("invalid renderer type: %T", diff.Renderer)
+			return
+		}
+	}
+}
+
 func ValidateObject(attributes map[string]ValidateDiffFunction, action plans.Action, replace bool) ValidateDiffFunction {
 	return func(t *testing.T, diff computed.Diff) {
 		validateDiff(t, diff, action, replace)
@@ -121,6 +135,12 @@ func validateKeys[C, V any](t *testing.T, actual map[string]C, expected map[stri
 		if diff := cmp.Diff(actualAttributes, expectedAttributes); len(diff) > 0 {
 			t.Errorf("actual and expected attributes did not match: %s", diff)
 		}
+	} else {
+		gotKeys := slices.Sorted(maps.Keys(actual))
+		wantKeys := slices.Sorted(maps.Keys(expected))
+		if diff := cmp.Diff(wantKeys, gotKeys); len(diff) > 0 {
+			t.Errorf("keys not match: %s", diff)
+		}
 	}
 }
 

internal/command/jsonformat/computed/renderers/write_only.go

@@ -0,0 +1,24 @@
+// Copyright (c) The OpenTofu Authors
+// SPDX-License-Identifier: MPL-2.0
+// Copyright (c) 2023 HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package renderers
+
+import (
+	"fmt"
+
+	"github.com/opentofu/opentofu/internal/command/jsonformat/computed"
+)
+
+func WriteOnly() computed.DiffRenderer {
+	return &writeOnlyRenderer{}
+}
+
+type writeOnlyRenderer struct {
+	NoWarningsRenderer
+}
+
+func (renderer writeOnlyRenderer) RenderHuman(diff computed.Diff, _ int, opts computed.RenderHumanOpts) string {
+	return fmt.Sprintf("(write-only attribute)%s%s", forcesReplacement(diff.Replace, opts), nullSuffix(diff.Action, opts))
+}