internal/fwserver: Ensure Attribute and Block Plan Modification Retur…

…ns Custom Value Type Implementations When Using Custom Type NestedAttributeObject/NestedBlockObject (#823)

* internal/fwserver: Attribute plan modification returns custom value type implementations for list, map, set nested attributes using a nested object with a custom type (#821)

Reference: #768
Reference: #767

* internal/fwserver: Block plan modification returns custom value type implementations for list, set nested blocks using a nested object with a custom type (#821)

Reference: #768
Reference: #767

* Using testschema throughout tests for attribute and block plan modifier (#821)

* Renaming attr and updating tests (#821)

* Add changelog entry (#821)

* Removing hardcoded AttrTypes (#821)

.changes/unreleased/BUG FIXES-20230816-113531.yaml

@@ -0,0 +1,6 @@
+kind: BUG FIXES
+body: 'internal/fwserver: Prevented `Invalid Element Type` diagnostics for nested
+  attributes and blocks implementing `CustomType` field'
+time: 2023-08-16T11:35:31.553124+01:00
+custom:
+  Issue: "823"

internal/fwserver/attribute_plan_modification.go

@@ -193,6 +193,22 @@ func AttributeModifyPlan(ctx context.Context, a fwschema.Attribute, req ModifyAt
 				return
 			}
 
+			planObjectValuable, diags := coerceObjectValuable(ctx, attrPath, planElem)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			typable, diags := coerceObjectTypable(ctx, attrPath, planObjectValuable)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
 			stateObject, diags := listElemObject(ctx, attrPath, stateList, idx, fwschemadata.DataDescriptionState)
 
 			resp.Diagnostics.Append(diags...)
@@ -219,7 +235,26 @@ func AttributeModifyPlan(ctx context.Context, a fwschema.Attribute, req ModifyAt
 
 			NestedAttributeObjectPlanModify(ctx, nestedAttributeObject, objectReq, objectResp)
 
-			planElements[idx] = objectResp.AttributePlan
+			respValue, diags := coerceObjectValue(ctx, attrPath, objectResp.AttributePlan)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			// A custom value type must be returned in the final response to prevent
+			// later correctness errors.
+			// Reference: https://github.com/hashicorp/terraform-plugin-framework/issues/821
+			respValuable, diags := typable.ValueFromObject(ctx, respValue)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			planElements[idx] = respValuable
 			resp.Diagnostics.Append(objectResp.Diagnostics...)
 			resp.Private = objectResp.Private
 			resp.RequiresReplace.Append(objectResp.RequiresReplace...)
@@ -309,6 +344,22 @@ func AttributeModifyPlan(ctx context.Context, a fwschema.Attribute, req ModifyAt
 				return
 			}
 
+			planObjectValuable, diags := coerceObjectValuable(ctx, attrPath, planElem)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			typable, diags := coerceObjectTypable(ctx, attrPath, planObjectValuable)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
 			stateObject, diags := setElemObject(ctx, attrPath, stateSet, idx, fwschemadata.DataDescriptionState)
 
 			resp.Diagnostics.Append(diags...)
@@ -335,7 +386,26 @@ func AttributeModifyPlan(ctx context.Context, a fwschema.Attribute, req ModifyAt
 
 			NestedAttributeObjectPlanModify(ctx, nestedAttributeObject, objectReq, objectResp)
 
-			planElements[idx] = objectResp.AttributePlan
+			respValue, diags := coerceObjectValue(ctx, attrPath, objectResp.AttributePlan)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			// A custom value type must be returned in the final response to prevent
+			// later correctness errors.
+			// Reference: https://github.com/hashicorp/terraform-plugin-framework/issues/821
+			respValuable, diags := typable.ValueFromObject(ctx, respValue)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			planElements[idx] = respValuable
 			resp.Diagnostics.Append(objectResp.Diagnostics...)
 			resp.Private = objectResp.Private
 			resp.RequiresReplace.Append(objectResp.RequiresReplace...)
@@ -425,6 +495,22 @@ func AttributeModifyPlan(ctx context.Context, a fwschema.Attribute, req ModifyAt
 				return
 			}
 
+			planObjectValuable, diags := coerceObjectValuable(ctx, attrPath, planElem)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			typable, diags := coerceObjectTypable(ctx, attrPath, planObjectValuable)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
 			stateObject, diags := mapElemObject(ctx, attrPath, stateMap, key, fwschemadata.DataDescriptionState)
 
 			resp.Diagnostics.Append(diags...)
@@ -451,7 +537,26 @@ func AttributeModifyPlan(ctx context.Context, a fwschema.Attribute, req ModifyAt
 
 			NestedAttributeObjectPlanModify(ctx, nestedAttributeObject, objectReq, objectResp)
 
-			planElements[key] = objectResp.AttributePlan
+			respValue, diags := coerceObjectValue(ctx, attrPath, objectResp.AttributePlan)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			// A custom value type must be returned in the final response to prevent
+			// later correctness errors.
+			// Reference: https://github.com/hashicorp/terraform-plugin-framework/issues/821
+			respValuable, diags := typable.ValueFromObject(ctx, respValue)
+
+			resp.Diagnostics.Append(diags...)
+
+			if resp.Diagnostics.HasError() {
+				return
+			}
+
+			planElements[key] = respValuable
 			resp.Diagnostics.Append(objectResp.Diagnostics...)
 			resp.Private = objectResp.Private
 			resp.RequiresReplace.Append(objectResp.RequiresReplace...)