Merge pull request #15 from iamd3vil/fix/default-fields-odd

Fix panic in case of odd fields while default fields are not nil.

log.go

@@ -87,6 +87,10 @@ func New(opts Opts) Logger {
 		opts.CallerSkipFrameCount = 3
 	}
 
+	if len(opts.DefaultFields)%2 != 0 {
+		opts.DefaultFields = opts.DefaultFields[0 : len(opts.DefaultFields)-1]
+	}
+
 	return Logger{
 		out:  newSyncWriter(opts.Writer),
 		Opts: opts,
@@ -195,7 +199,7 @@ func (l Logger) handleLog(msg string, lvl Level, fields ...any) {
 
 	// If there are odd number of fields, ignore the last.
 	if fieldCount%2 != 0 {
-		fields = fields[0 : fieldCount-1]
+		fields = fields[0 : len(fields)-1]
 	}
 
 	for i := range l.DefaultFields {

log_test.go

@@ -223,6 +223,18 @@ func TestOddNumberedFields(t *testing.T) {
 	buf.Reset()
 }
 
+func TestOddNumberedFieldsWithDefaultFields(t *testing.T) {
+	buf := &bytes.Buffer{}
+	l := New(Opts{Writer: buf, DefaultFields: []any{
+		"defaultkey", "defaultval",
+	}})
+
+	// Give a odd number of fields.
+	l.Info("hello world", "key1", "val1", "key2")
+	require.Contains(t, buf.String(), `level=info message="hello world" defaultkey=defaultval key1=val1`)
+	buf.Reset()
+}
+
 // These test are typically meant to be run with the data race detector.
 func TestLoggerConcurrency(t *testing.T) {
 	buf := &bytes.Buffer{}