fix timestamp serialization zero data <-> zeroTimestamp

Changes:
1) Unmarshalling `zero data` into `time.Time` return `time.Time{}` before, now returns `zeroTimestamp`
2) Marshalling the `0001-1-1T00:00:00Z` value of the `time.Time` return `zero data` before, now returns a data that is equivalent to the difference between `0001-1-1T00:00:00Z` and `1970-1-1T00:00:00Z`
3) Tests fixed

cassandra_test.go

@@ -2075,7 +2075,9 @@ func TestNilInQuery(t *testing.T) {
 
 // Don't initialize time.Time bind variable if cassandra timestamp column is empty
 func TestEmptyTimestamp(t *testing.T) {
+	zeroTimestamp := time.UnixMilli(0).UTC()
 	session := createSession(t)
+
 	defer session.Close()
 
 	if err := createTable(session, "CREATE TABLE gocql_test.test_empty_timestamp (id int, time timestamp, num int, PRIMARY KEY (id))"); err != nil {
@@ -2092,8 +2094,8 @@ func TestEmptyTimestamp(t *testing.T) {
 		t.Fatalf("failed to select with err: %v", err)
 	}
 
-	if !timeVal.IsZero() {
-		t.Errorf("time.Time bind variable should still be empty (was %s)", timeVal)
+	if !timeVal.Equal(zeroTimestamp) {
+		t.Errorf("time.Time bind variable should be zero (was %s)", timeVal)
 	}
 }
 

serialization/timestamp/marshal_utils.go

@@ -27,9 +27,6 @@ func EncTime(v time.Time) ([]byte, error) {
 	if v.After(maxTimestamp) || v.Before(minTimestamp) {
 		return nil, fmt.Errorf("failed to marshal timestamp: the (%T)(%s) value should be in the range from -292275055-05-16T16:47:04.192Z to 292278994-08-17T07:12:55.807", v, v.Format(time.RFC3339Nano))
 	}
-	if v.IsZero() {
-		return make([]byte, 0), nil
-	}
 	ms := v.Unix()*1e3 + int64(v.Nanosecond())/1e6
 	return []byte{byte(ms >> 56), byte(ms >> 48), byte(ms >> 40), byte(ms >> 32), byte(ms >> 24), byte(ms >> 16), byte(ms >> 8), byte(ms)}, nil
 }

serialization/timestamp/unmarshal_utils.go

@@ -55,7 +55,7 @@ func DecTime(p []byte, v *time.Time) error {
 	}
 	switch len(p) {
 	case 0:
-		*v = time.Time{}
+		*v = zeroTimestamp
 	case 8:
 		*v = decTime(p)
 	default:
@@ -73,7 +73,8 @@ func DecTimeR(p []byte, v **time.Time) error {
 		if p == nil {
 			*v = nil
 		} else {
-			*v = new(time.Time)
+			val := zeroTimestamp
+			*v = &val
 		}
 	case 8:
 		val := decTime(p)

tests/serialization/marshal_16_timestamp_test.go

@@ -40,12 +40,7 @@ func TestMarshalsTimestamp(t *testing.T) {
 		},
 	}
 
-	zeroTime := time.Unix(0, 0).UTC()
-
-	// The `time` package have a speciality - values `time.Time{}` and `time.Unix(0,0).UTC()` are different
-	// The old unmarshal function unmarshalls `nil` and `zero` data into `time.Time{}`, but data with zeros into `time.Unix(0,0).UTC()`
-	brokenTime := serialization.GetTypes(time.Time{}, &time.Time{})
-	_ = brokenTime
+	zeroTimestamp := time.Unix(0, 0).UTC()
 
 	for _, tSuite := range testSuites {
 		marshal := tSuite.marshal
@@ -62,23 +57,21 @@ func TestMarshalsTimestamp(t *testing.T) {
 			serialization.PositiveSet{
 				Data: nil,
 				Values: mod.Values{
-					int64(0), zeroTime,
+					int64(0), zeroTimestamp,
 				}.AddVariants(mod.CustomType),
-				BrokenUnmarshalTypes: brokenTime,
 			}.Run("[nil]unmarshal", t, nil, unmarshal)
 
 			serialization.PositiveSet{
 				Data: make([]byte, 0),
 				Values: mod.Values{
-					int64(0), zeroTime,
+					int64(0), zeroTimestamp,
 				}.AddVariants(mod.All...),
-				BrokenUnmarshalTypes: brokenTime,
 			}.Run("[]unmarshal", t, nil, unmarshal)
 
 			serialization.PositiveSet{
 				Data: []byte("\x00\x00\x00\x00\x00\x00\x00\x00"),
 				Values: mod.Values{
-					int64(0), zeroTime,
+					int64(0), zeroTimestamp,
 				}.AddVariants(mod.All...),
 			}.Run("zeros", t, marshal, unmarshal)