fix: ensure user inputs are normalized (#724)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

backend/internal/dto/dto_normalize_test.go

@@ -0,0 +1,84 @@
+package dto
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"golang.org/x/text/unicode/norm"
+)
+
+type testDto struct {
+	Name        string `unorm:"nfc"`
+	Description string `unorm:"nfd"`
+	Other       string
+	BadForm     string `unorm:"bad"`
+}
+
+func TestNormalize(t *testing.T) {
+	input := testDto{
+		// Is in NFC form already
+		Name: norm.NFC.String("Café"),
+		// NFC form will be normalized to NFD
+		Description: norm.NFC.String("vërø"),
+		// Should be unchanged
+		Other: "NöTag",
+		// Should be unchanged
+		BadForm: "BåD",
+	}
+
+	Normalize(&input)
+
+	assert.Equal(t, norm.NFC.String("Café"), input.Name)
+	assert.Equal(t, norm.NFD.String("vërø"), input.Description)
+	assert.Equal(t, "NöTag", input.Other)
+	assert.Equal(t, "BåD", input.BadForm)
+}
+
+func TestNormalizeSlice(t *testing.T) {
+	obj1 := testDto{
+		Name:        norm.NFC.String("Café1"),
+		Description: norm.NFC.String("vërø1"),
+		Other:       "NöTag1",
+		BadForm:     "BåD1",
+	}
+	obj2 := testDto{
+		Name:        norm.NFD.String("Résumé2"),
+		Description: norm.NFD.String("accéléré2"),
+		Other:       "NöTag2",
+		BadForm:     "BåD2",
+	}
+
+	t.Run("slice of structs", func(t *testing.T) {
+		slice := []testDto{obj1, obj2}
+		Normalize(&slice)
+
+		// Verify first element
+		assert.Equal(t, norm.NFC.String("Café1"), slice[0].Name)
+		assert.Equal(t, norm.NFD.String("vërø1"), slice[0].Description)
+		assert.Equal(t, "NöTag1", slice[0].Other)
+		assert.Equal(t, "BåD1", slice[0].BadForm)
+
+		// Verify second element
+		assert.Equal(t, norm.NFC.String("Résumé2"), slice[1].Name)
+		assert.Equal(t, norm.NFD.String("accéléré2"), slice[1].Description)
+		assert.Equal(t, "NöTag2", slice[1].Other)
+		assert.Equal(t, "BåD2", slice[1].BadForm)
+	})
+
+	t.Run("slice of pointers to structs", func(t *testing.T) {
+		slice := []*testDto{&obj1, &obj2}
+		Normalize(&slice)
+
+		// Verify first element
+		assert.Equal(t, norm.NFC.String("Café1"), slice[0].Name)
+		assert.Equal(t, norm.NFD.String("vërø1"), slice[0].Description)
+		assert.Equal(t, "NöTag1", slice[0].Other)
+		assert.Equal(t, "BåD1", slice[0].BadForm)
+
+		// Verify second element
+		assert.Equal(t, norm.NFC.String("Résumé2"), slice[1].Name)
+		assert.Equal(t, norm.NFD.String("accéléré2"), slice[1].Description)
+		assert.Equal(t, "NöTag2", slice[1].Other)
+		assert.Equal(t, "BåD2", slice[1].BadForm)
+	})
+}