add more struct field tests

pkg/dynamic/iterate.go

@@ -11,6 +11,10 @@ type StructFieldIterator func(tag string, ft reflect.StructField, fv reflect.Val
 var ErrCanNotIterateNilPointer = errors.New("can not iterate struct on a nil pointer")
 
 func IterateFields(obj interface{}, cb func(ft reflect.StructField, fv reflect.Value) error) error {
+	if obj == nil {
+		return errors.New("can not iterate field, given object is nil")
+	}
+
 	sv := reflect.ValueOf(obj)
 	st := reflect.TypeOf(obj)
 

pkg/dynamic/iterate_test.go

@@ -9,17 +9,36 @@ import (
 )
 
 func TestIterateFields(t *testing.T) {
-	var a = struct {
-		A int
-		B float64
-		C *os.File
-	}{}
 
-	cnt := 0
-	err := IterateFields(&a, func(ft reflect.StructField, fv reflect.Value) error {
-		cnt++
-		return nil
+	t.Run("basic", func(t *testing.T) {
+		var a = struct {
+			A int
+			B float64
+			C *os.File
+		}{}
+
+		cnt := 0
+		err := IterateFields(&a, func(ft reflect.StructField, fv reflect.Value) error {
+			cnt++
+			return nil
+		})
+		assert.NoError(t, err)
+		assert.Equal(t, 3, cnt)
 	})
-	assert.NoError(t, err)
-	assert.Equal(t, 3, cnt)
+
+	t.Run("non-ptr", func(t *testing.T) {
+		err := IterateFields(struct{}{}, func(ft reflect.StructField, fv reflect.Value) error {
+			return nil
+		})
+		assert.Error(t, err)
+	})
+
+	t.Run("nil", func(t *testing.T) {
+		err := IterateFields(nil, func(ft reflect.StructField, fv reflect.Value) error {
+			return nil
+		})
+		assert.Error(t, err)
+	})
+
+
 }