Truncate nanoseconds in EncodeText for Timestamptz and Timestamp

PostgreSQL has microsecond precision. If more than this precision is
supplied in the text format it is rounded. This was inconsistent with
the binary format.

See https://github.com/jackc/pgx/issues/699 for original issue.

timestamp.go

@@ -158,7 +158,7 @@ func (src Timestamp) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 
 	switch src.InfinityModifier {
 	case None:
-		s = src.Time.Format(pgTimestampFormat)
+		s = src.Time.Truncate(time.Microsecond).Format(pgTimestampFormat)
 	case Infinity:
 		s = "infinity"
 	case NegativeInfinity:

timestamp_test.go

@@ -32,6 +32,51 @@ func TestTimestampTranscode(t *testing.T) {
 	})
 }
 
+func TestTimestampNanosecondsTruncated(t *testing.T) {
+	tests := []struct {
+		input    time.Time
+		expected time.Time
+	}{
+		{time.Date(2020, 1, 1, 0, 0, 0, 999999999, time.UTC), time.Date(2020, 1, 1, 0, 0, 0, 999999000, time.UTC)},
+		{time.Date(2020, 1, 1, 0, 0, 0, 999999001, time.UTC), time.Date(2020, 1, 1, 0, 0, 0, 999999000, time.UTC)},
+	}
+	for i, tt := range tests {
+		{
+			ts := pgtype.Timestamp{Time: tt.input, Status: pgtype.Present}
+			buf, err := ts.EncodeText(nil, nil)
+			if err != nil {
+				t.Errorf("%d. EncodeText failed - %v", i, err)
+			}
+
+			ts.DecodeText(nil, buf)
+			if err != nil {
+				t.Errorf("%d. DecodeText failed - %v", i, err)
+			}
+
+			if !(ts.Status == pgtype.Present && ts.Time.Equal(tt.expected)) {
+				t.Errorf("%d. EncodeText did not truncate nanoseconds", i)
+			}
+		}
+
+		{
+			ts := pgtype.Timestamp{Time: tt.input, Status: pgtype.Present}
+			buf, err := ts.EncodeBinary(nil, nil)
+			if err != nil {
+				t.Errorf("%d. EncodeBinary failed - %v", i, err)
+			}
+
+			ts.DecodeBinary(nil, buf)
+			if err != nil {
+				t.Errorf("%d. DecodeBinary failed - %v", i, err)
+			}
+
+			if !(ts.Status == pgtype.Present && ts.Time.Equal(tt.expected)) {
+				t.Errorf("%d. EncodeBinary did not truncate nanoseconds", i)
+			}
+		}
+	}
+}
+
 func TestTimestampSet(t *testing.T) {
 	type _time time.Time
 

timestamptz.go

@@ -160,7 +160,7 @@ func (src Timestamptz) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
 
 	switch src.InfinityModifier {
 	case None:
-		s = src.Time.UTC().Format(pgTimestamptzSecondFormat)
+		s = src.Time.UTC().Truncate(time.Microsecond).Format(pgTimestamptzSecondFormat)
 	case Infinity:
 		s = "infinity"
 	case NegativeInfinity:

timestamptz_test.go

@@ -32,6 +32,51 @@ func TestTimestamptzTranscode(t *testing.T) {
 	})
 }
 
+func TestTimestamptzNanosecondsTruncated(t *testing.T) {
+	tests := []struct {
+		input    time.Time
+		expected time.Time
+	}{
+		{time.Date(2020, 1, 1, 0, 0, 0, 999999999, time.Local), time.Date(2020, 1, 1, 0, 0, 0, 999999000, time.Local)},
+		{time.Date(2020, 1, 1, 0, 0, 0, 999999001, time.Local), time.Date(2020, 1, 1, 0, 0, 0, 999999000, time.Local)},
+	}
+	for i, tt := range tests {
+		{
+			tstz := pgtype.Timestamptz{Time: tt.input, Status: pgtype.Present}
+			buf, err := tstz.EncodeText(nil, nil)
+			if err != nil {
+				t.Errorf("%d. EncodeText failed - %v", i, err)
+			}
+
+			tstz.DecodeText(nil, buf)
+			if err != nil {
+				t.Errorf("%d. DecodeText failed - %v", i, err)
+			}
+
+			if !(tstz.Status == pgtype.Present && tstz.Time.Equal(tt.expected)) {
+				t.Errorf("%d. EncodeText did not truncate nanoseconds", i)
+			}
+		}
+
+		{
+			tstz := pgtype.Timestamptz{Time: tt.input, Status: pgtype.Present}
+			buf, err := tstz.EncodeBinary(nil, nil)
+			if err != nil {
+				t.Errorf("%d. EncodeBinary failed - %v", i, err)
+			}
+
+			tstz.DecodeBinary(nil, buf)
+			if err != nil {
+				t.Errorf("%d. DecodeBinary failed - %v", i, err)
+			}
+
+			if !(tstz.Status == pgtype.Present && tstz.Time.Equal(tt.expected)) {
+				t.Errorf("%d. EncodeBinary did not truncate nanoseconds", i)
+			}
+		}
+	}
+}
+
 func TestTimestamptzSet(t *testing.T) {
 	type _time time.Time