chore: utilities to handle labels and selectors (#881)

Will be used in #817

Author: apricote

internal/util/datasourceutil/labels.go

@@ -0,0 +1,33 @@
+package datasourceutil
+
+import (
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-framework/diag"
+)
+
+// GetOneResultForLabelSelector verifies that only one item is returned for a label selector. If none or >1 are returned
+// it returns an error [diag.Diagnostic].
+func GetOneResultForLabelSelector[T any](resourceName string, items []*T, labelSelector string) (*T, diag.Diagnostic) {
+	if len(items) == 0 {
+		return nil, diag.NewErrorDiagnostic(fmt.Sprintf("No %s found for label selector", resourceName), fmt.Sprintf(
+			"No %s found for label selector.\n\n"+
+				"Label selector: %s\n",
+			resourceName,
+			labelSelector,
+		))
+	}
+	if len(items) > 1 {
+		return nil, diag.NewErrorDiagnostic(
+			fmt.Sprintf("More than one %s found for label selector", resourceName),
+			fmt.Sprintf(
+				"More than one %s found for label selector.\n\n"+
+					"Label selector: %s\n",
+				resourceName,
+				labelSelector,
+			),
+		)
+	}
+
+	return items[0], nil
+}

internal/util/datasourceutil/labels_test.go

@@ -0,0 +1,67 @@
+package datasourceutil
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-framework/diag"
+)
+
+func TestGetOneResultForLabelSelector(t *testing.T) {
+	type item struct{ ID int }
+
+	type args struct {
+		resourceName  string
+		items         []*item
+		labelSelector string
+	}
+	type testCase struct {
+		name       string
+		args       args
+		want       *item
+		diagnostic diag.Diagnostic
+	}
+	tests := []testCase{
+		{
+			name: "one item",
+			args: args{
+				resourceName:  "item",
+				items:         []*item{{ID: 1}},
+				labelSelector: "foo=bar",
+			},
+			want:       &item{ID: 1},
+			diagnostic: nil,
+		},
+		{
+			name: "zero items",
+			args: args{
+				resourceName:  "item",
+				items:         []*item{},
+				labelSelector: "foo=bar",
+			},
+			want:       nil,
+			diagnostic: diag.NewErrorDiagnostic("No item found for label selector", "No item found for label selector.\n\nLabel selector: foo=bar\n"),
+		},
+		{
+			name: "two items",
+			args: args{
+				resourceName:  "item",
+				items:         []*item{{ID: 1}, {ID: 2}},
+				labelSelector: "foo=bar",
+			},
+			want:       nil,
+			diagnostic: diag.NewErrorDiagnostic("More than one item found for label selector", "More than one item found for label selector.\n\nLabel selector: foo=bar\n"),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotItem, gotDiagnostic := GetOneResultForLabelSelector(tt.args.resourceName, tt.args.items, tt.args.labelSelector)
+			if !reflect.DeepEqual(gotItem, tt.want) {
+				t.Errorf("GetOneResultForLabelSelector() got = %v, want %v", gotItem, tt.want)
+			}
+			if !reflect.DeepEqual(gotDiagnostic, tt.diagnostic) {
+				t.Errorf("GetOneResultForLabelSelector() got1 = %v, want %v", gotDiagnostic, tt.diagnostic)
+			}
+		})
+	}
+}

internal/util/resourceutil/labels.go

@@ -3,6 +3,7 @@ package resourceutil
 import (
 	"context"
 
+	"github.com/hashicorp/terraform-plugin-framework/diag"
 	"github.com/hashicorp/terraform-plugin-framework/resource/schema"
 	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
 	"github.com/hashicorp/terraform-plugin-framework/types"
@@ -47,3 +48,15 @@ func LabelsSchema() schema.MapAttribute {
 		},
 	}
 }
+
+// LabelsMapValueFrom prepare the labels from the API to be assigned into the resource model.
+//
+// In the resource schemas, labels can be null, but the API always returns an empty object for labels.
+// This causes a conflict in the Terraform Data Consistency check. This method handles empty label
+// objects by instead returning a null map.
+func LabelsMapValueFrom(ctx context.Context, in map[string]string) (types.Map, diag.Diagnostics) {
+	if len(in) > 0 {
+		return types.MapValueFrom(ctx, types.StringType, in)
+	}
+	return types.MapNull(types.StringType), nil
+}

internal/util/resourceutil/labels_test.go

@@ -2,6 +2,7 @@ package resourceutil
 
 import (
 	"context"
+	"reflect"
 	"sort"
 	"testing"
 
@@ -79,3 +80,36 @@ func TestLabelsValidator_ValidateMap(t *testing.T) {
 		})
 	}
 }
+
+func TestLabelsMapValueFrom(t *testing.T) {
+	tests := []struct {
+		name  string
+		in    map[string]string
+		want  types.Map
+		diags diag.Diagnostics
+	}{
+		{
+			name:  "Map with Labels",
+			in:    map[string]string{"foo": "bar"},
+			want:  types.MapValueMust(types.StringType, map[string]attr.Value{"foo": types.StringValue("bar")}),
+			diags: nil,
+		},
+		{
+			name:  "Empty Map",
+			in:    map[string]string{},
+			want:  types.MapNull(types.StringType),
+			diags: nil,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			labels, diags := LabelsMapValueFrom(context.Background(), tt.in)
+			if !reflect.DeepEqual(labels, tt.want) {
+				t.Errorf("LabelsMapValueFrom() got = %v, want %v", labels, tt.want)
+			}
+			if !reflect.DeepEqual(diags, tt.diags) {
+				t.Errorf("LabelsMapValueFrom() got1 = %v, want %v", diags, tt.diags)
+			}
+		})
+	}
+}