diff --git a/mapper/mock_test.go b/mapper/mock_test.go
index bc643d1..5ed0416 100644
--- a/mapper/mock_test.go
+++ b/mapper/mock_test.go
@@ -11,23 +11,59 @@ func dummyMockMapperFct(res *string, tag []*TagItem) error {
 
 func TestMockRetag(t *testing.T) {
 	testData := []struct {
-		inputResourceTags, outputResourceTags map[string]map[string]string
-		inputResourceKeys, outputResourceKeys map[string][]string
+		existingTags, inputResourceTags, outputResourceTags map[string]map[string]string
+		existingKeys, inputResourceKeys, outputResourceKeys map[string][]string
 	}{
-		{map[string]map[string]string{}, nil, map[string][]string{}, nil},
+		{nil, map[string]map[string]string{}, nil, nil, map[string][]string{}, nil},
 		{
 			map[string]map[string]string{"foo": {"key1": "value1"}, "bar": {"key2": "value2", "key3": "value3"}, "joe": nil},
+			map[string]map[string]string{},
 			map[string]map[string]string{"foo": {"key1": "value1"}, "bar": {"key2": "value2", "key3": "value3"}, "joe": nil},
+			map[string][]string{"joe": {"mykey4"}, "bar": {"key3"}},
+			map[string][]string{},
+			map[string][]string{"joe": {"mykey4"}, "bar": {"key3"}},
+		},
+		{
+			map[string]map[string]string{"foo": {"key1": "value1"}, "bar": {"key2": "value2", "key3": "value3"}, "joe": nil},
+			map[string]map[string]string{"foo": {"tofoo1": "spicy1"}},
+			map[string]map[string]string{"foo": {"key1": "value1", "tofoo1": "spicy1"}, "bar": {"key2": "value2", "key3": "value3"}, "joe": nil},
+			map[string][]string{"joe": {"mykey4"}, "bar": {"key6"}},
+			map[string][]string{"joe": {"mykey4"}, "bar": {"key3", "key8"}},
+			map[string][]string{"foo": nil, "joe": {"mykey4", "mykey4"}, "bar": {"key6", "key3", "key8"}},
+		},
+		{
+			nil,
+			map[string]map[string]string{"foo": {"key1": "value1"}, "bar": {"key2": "value2", "key3": "value3"}, "joe": nil},
+			map[string]map[string]string{"foo": {"key1": "value1"}, "bar": {"key2": "value2", "key3": "value3"}, "joe": nil},
+			nil,
 			map[string][]string{"bar": {"mykey1", "mykey2"}, "joe": {"mykey3"}},
 			map[string][]string{"foo": nil, "bar": {"mykey1", "mykey2"}, "joe": {"mykey3"}},
 		},
 	}
 
 	for _, d := range testData {
-		m := MockMapper{}
-		for k, v := range d.inputResourceTags {
-			inKeys := []string{}
-			inKeys, _ = d.inputResourceKeys[k]
+		m := MockMapper{ResourceTags: d.existingTags, ResourceKeys: d.existingKeys}
+		resources := []string{}
+		for k := range d.inputResourceTags {
+			resources = append(resources, k)
+		}
+		for k := range d.inputResourceKeys {
+			// Only add if not already there
+			found := false
+			for _, rez := range resources {
+				if rez == k {
+					found = true
+					break
+				}
+			}
+			if !found {
+				resources = append(resources, k)
+			}
+		}
+		for _, k := range resources {
+			v, _ := d.inputResourceTags[k]
+			inKeys, _ := d.inputResourceKeys[k]
+			t.Logf("%s, %v, %v", k, v, inKeys)
 			m.Retag(&k, &v, inKeys, nil)
 		}
 		if !reflect.DeepEqual(d.outputResourceTags, m.ResourceTags) {