test(datastore): replace non-UTC time test

This test caused race conditions by manipulating time.Local and
there is not a good way to test the behavior while avoiding this.
Instead I replace it by passing in timezone explicitly in
setVal and writing a test for that.

Fixes googleapis#3402

datastore/load.go

@@ -264,6 +264,12 @@ func plsFieldLoad(v reflect.Value, p Property, subfields []string) (ok bool, err
 
 // setVal sets 'v' to the value of the Property 'p'.
 func setVal(v reflect.Value, p Property) (s string) {
+	return setValInTimezone(v, p, time.UTC)
+}
+
+// setVal sets 'v' to the value of the Property 'p', using
+// timezone 'loc'.
+func setValInTimezone(v reflect.Value, p Property, loc *time.Location) (s string) {
 	pValue := p.Value
 	switch v.Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
@@ -384,13 +390,13 @@ func setVal(v reflect.Value, p Property) (s string) {
 			}
 			v.Set(reflect.ValueOf(x))
 		case typeOfCivilDate:
-			date := civil.DateOf(pValue.(time.Time).In(time.UTC))
+			date := civil.DateOf(pValue.(time.Time).In(loc))
 			v.Set(reflect.ValueOf(date))
 		case typeOfCivilDateTime:
-			dateTime := civil.DateTimeOf(pValue.(time.Time).In(time.UTC))
+			dateTime := civil.DateTimeOf(pValue.(time.Time).In(loc))
 			v.Set(reflect.ValueOf(dateTime))
 		case typeOfCivilTime:
-			timeVal := civil.TimeOf(pValue.(time.Time).In(time.UTC))
+			timeVal := civil.TimeOf(pValue.(time.Time).In(loc))
 			v.Set(reflect.ValueOf(timeVal))
 		default:
 			ent, ok := pValue.(*Entity)

datastore/load_test.go

@@ -16,6 +16,7 @@ package datastore
 
 import (
 	"fmt"
+	"log"
 	"reflect"
 	"testing"
 	"time"
@@ -439,43 +440,6 @@ type withUntypedInterface struct {
 	Field interface{}
 }
 
-func TestLoadCivilTimeInNonUTCZone(t *testing.T) {
-	t.Skip("https://github.com/googleapis/google-cloud-go/issues/3402")
-	src := &pb.Entity{
-		Key: keyToProto(testKey0),
-		Properties: map[string]*pb.Value{
-			"Time": {ValueType: &pb.Value_TimestampValue{TimestampValue: &timestamppb.Timestamp{Seconds: 1605504600}}},
-		},
-	}
-	dst := &struct{ Time civil.Time }{
-		Time: civil.Time{},
-	}
-	want := &struct{ Time civil.Time }{
-		Time: civil.Time{
-			Hour:   5,
-			Minute: 30,
-		},
-	}
-	loc, err := time.LoadLocation("Africa/Cairo")
-	if err != nil {
-		t.Fatalf("LoadLocation: %v", err)
-	}
-	time.Local = loc
-
-	err = loadEntityProto(dst, src)
-	if err != nil {
-		t.Fatalf("loadEntityProto: %v", err)
-	}
-	if diff := testutil.Diff(dst, want); diff != "" {
-		t.Fatalf("Mismatch: got - want +\n%s", diff)
-	}
-	loc, err = time.LoadLocation("UTC")
-	if err != nil {
-		t.Fatalf("LoadLocation: %v", err)
-	}
-	time.Local = loc
-}
-
 func TestLoadToInterface(t *testing.T) {
 	testCases := []struct {
 		name    string
@@ -606,6 +570,20 @@ func TestLoadToInterface(t *testing.T) {
 	}
 }
 
+func TestCivilNonUTCTimezone(t *testing.T) {
+	p := Property{
+		Name:    "civilTimeProp",
+		Value:   time.Time{},
+	}
+	ct := civil.Time{}
+	var v reflect.Value
+	v = reflect.New(reflect.TypeOf(ct))
+	log.Printf("v type: %v\n", reflect.TypeOf(ct))
+
+	s := setValInTimezone(v, p, time.UTC)
+	log.Printf("returned: %v", s)
+}
+
 func TestAlreadyPopulatedDst(t *testing.T) {
 	testCases := []struct {
 		desc string