test: check custom (un)marshalling for RFC 8141 URNs

Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>

Author: leodido

urn8141_test.go

@@ -0,0 +1,51 @@
+package urn
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestURN8141JSONMarshaling(t *testing.T) {
+	t.Run("roundtrip", func(t *testing.T) {
+		// Marshal
+		expected := URN8141{
+			URN: &URN{
+				ID:         "lex",
+				SS:         "it:ministero.giustizia:decreto:1992-07-24;358~art5",
+				rComponent: "r",
+				qComponent: "q%D0",
+				fComponent: "frag",
+			},
+		}
+		bytes, err := json.Marshal(expected)
+		if !assert.NoError(t, err) {
+			return
+		}
+		require.Equal(t, `"urn:lex:it:ministero.giustizia:decreto:1992-07-24;358~art5?+r?=q%D0#frag"`, string(bytes))
+		// Unmarshal
+		var got URN8141
+		err = json.Unmarshal(bytes, &got)
+		if !assert.NoError(t, err) {
+			return
+		}
+		assert.Equal(t, expected.String(), got.String())
+		assert.Equal(t, expected.fComponent, got.FComponent())
+		assert.Equal(t, expected.qComponent, got.QComponent())
+		assert.Equal(t, expected.rComponent, got.RComponent())
+	})
+
+	t.Run("invalid URN", func(t *testing.T) {
+		var actual URN8141
+		err := json.Unmarshal([]byte(`"not a URN"`), &actual)
+		assert.EqualError(t, err, "invalid URN per RFC 8141: not a URN")
+	})
+
+	t.Run("empty", func(t *testing.T) {
+		var actual URN8141
+		err := actual.UnmarshalJSON(nil)
+		assert.EqualError(t, err, "unexpected end of JSON input")
+	})
+}