fix: spanlogger should support log.Valuer (#209)

Author: Reasno

logging/log.go

@@ -95,14 +95,23 @@ func LevelFilter(levelCfg string) level.Option {
 	}
 }
 
+type span interface {
+	LogKV(alternatingKeyValues ...interface{})
+}
+
 type spanLogger struct {
-	span opentracing.Span
+	span span
 	base log.Logger
 	kvs  []interface{}
 }
 
 func (s spanLogger) Log(keyvals ...interface{}) error {
 	s.kvs = append(s.kvs, keyvals...)
+	for k := range s.kvs {
+		if f, ok := s.kvs[k].(log.Valuer); ok {
+			s.kvs[k] = f()
+		}
+	}
 	s.span.LogKV(s.kvs...)
 	return s.base.Log(s.kvs...)
 }

logging/log_test.go

@@ -51,3 +51,22 @@ func TestWithContext(t *testing.T) {
 	ll.Log("baz", "qux")
 	assert.Contains(t, buf.String(), "foo=bar baz=qux")
 }
+
+type mockSpan struct {
+	received []interface{}
+}
+
+func (m *mockSpan) LogKV(alternatingKeyValues ...interface{}) {
+	m.received = alternatingKeyValues
+}
+
+func TestSpanLogger(t *testing.T) {
+	var mock mockSpan
+	spanLogger{
+		span: &mock,
+		base: log.NewNopLogger(),
+		kvs:  []interface{}{"foo", "bar"},
+	}.Log("baz", log.Valuer(func() interface{} { return "qux" }))
+
+	assert.Equal(t, []interface{}{"foo", "bar", "baz", "qux"}, mock.received)
+}