feat: add_testing (#45)

## Description

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At least please give us some description what you are trying to achieve and why your change is needed. -->

relates to #1234

## Checklist

- [ ] Issue was linked above
- [ ] Code format was applied: `make fmt`
- [ ] Examples were added / adjusted (see `examples/` directory)
- [x] Docs are up-to-date: `make generate-docs` (will be checked by CI)
- [ ] Unit tests got implemented or updated
- [ ] Acceptance tests got implemented or updated (see e.g. [here](f5f99d1709/stackit/internal/services/dns/dns_acc_test.go))
- [x] Unit tests are passing: `make test` (will be checked by CI)
- [x] No linter issues: `make lint` (will be checked by CI)

Reviewed-on: #45
Reviewed-by: Andre_Harms <andre.harms@stackit.cloud>
Co-authored-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>
Co-committed-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>

stackit/internal/services/postgresflexalpha/user/mapper.go

@@ -111,7 +111,7 @@ func mapResourceFields(userResp *postgresflex.GetUserResponse, model *resourceMo
 	user := userResp
 
 	var userId int64
-	if model.UserId.ValueInt64() != 0 {
+	if !model.UserId.IsNull() && !model.UserId.IsUnknown() && model.UserId.ValueInt64() != 0 {
 		userId = model.UserId.ValueInt64()
 	} else if user.Id != nil {
 		userId = *user.Id

stackit/internal/services/postgresflexalpha/user/resource.go

@@ -10,7 +10,6 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/hashicorp/terraform-plugin-framework/attr"
 	"github.com/hashicorp/terraform-plugin-framework/diag"
 	"github.com/hashicorp/terraform-plugin-framework/resource/identityschema"
 	postgresflex "tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/pkg_gen/postgresflexalpha"
@@ -503,45 +502,6 @@ func (r *userResource) IdentitySchema(
 	}
 }
 
-func mapFields(userResp *postgresflex.GetUserResponse, model *resourceModel, region string) error {
-	if userResp == nil {
-		return fmt.Errorf("response is nil")
-	}
-	if model == nil {
-		return fmt.Errorf("model input is nil")
-	}
-	user := userResp
-
-	var userId int64
-	if model.UserId.ValueInt64() != 0 {
-		userId = model.UserId.ValueInt64()
-	} else if user.Id != nil {
-		userId = *user.Id
-	} else {
-		return fmt.Errorf("user id not present")
-	}
-
-	model.UserId = types.Int64Value(userId)
-	model.Name = types.StringPointerValue(user.Name)
-
-	if user.Roles == nil {
-		model.Roles = types.List(types.SetNull(types.StringType))
-	} else {
-		var roles []attr.Value
-		for _, role := range *user.Roles {
-			roles = append(roles, types.StringValue(string(role)))
-		}
-		rolesSet, diags := types.SetValue(types.StringType, roles)
-		if diags.HasError() {
-			return fmt.Errorf("failed to map roles: %w", core.DiagsToError(diags))
-		}
-		model.Roles = types.List(rolesSet)
-	}
-	model.Region = types.StringValue(region)
-	model.Status = types.StringPointerValue(user.Status)
-	return nil
-}
-
 // getUserResource refreshes the resource state by calling the API and mapping the response to the model.
 // Returns true if the resource state was successfully refreshed, false if the resource does not exist.
 func (r *userResource) getUserResource(ctx context.Context, model *resourceModel, arg *clientArg) (bool, error) {