diff --git a/pkg/structure/value_test.go b/pkg/structure/value_test.go
index 4e660e6..71558b1 100644
--- a/pkg/structure/value_test.go
+++ b/pkg/structure/value_test.go
@@ -84,3 +84,35 @@ func TestValue_InferValue(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, f, -1.2)
 }
+
+func TestValue_ChangeValue(t *testing.T) {
+	value := NewValue()
+	oldLen := value.GetLength()
+	chanageLen := value.ChangeValueLength(func() {
+		value.SetString("小葵花课堂开课了")
+	})
+	require.Equal(t, chanageLen, int64(value.GetLength()-oldLen))
+
+	lens := value.ChangeValueLength(func() {
+		value.SetInt(100)
+	})
+	require.Equal(t, lens, int64(-16))
+
+	lengs := value.ChangeValueLength(func() {
+		value.SetFloat64(9.99)
+	})
+	require.Equal(t, lengs, int64(0))
+
+	value = NewValue()
+	lengs = value.ChangeValueLength(func() {
+		value.SetFloat64(10.99)
+	})
+	require.Equal(t, lengs, int64(0))
+
+	value = NewValue()
+	value.SetString("909awdawdawd")
+	lengs = value.ChangeValueLength(func() {
+		value.SetString("9akjwbddddddddddddddddddddddddddddddddddddddddddddd")
+	})
+	require.Equal(t, lengs, int64(39))
+}