add json processor

processor/json/processor.go

@@ -0,0 +1,19 @@
+package json //nolint:revive
+
+import (
+	"context"
+
+	"gitoa.ru/go-4devs/config"
+	"gitoa.ru/go-4devs/config/param"
+	"gitoa.ru/go-4devs/config/value"
+)
+
+//nolint:revive
+func Json(_ context.Context, in config.Value, _ ...param.Option) (config.Value, error) {
+	data, err := in.ParseString()
+	if err != nil {
+		return in, nil //nolint:nilerr
+	}
+
+	return value.JString(data), nil
+}

processor/json/processor_test.go

@@ -0,0 +1,48 @@
+package json_test
+
+import (
+	"context"
+	"testing"
+
+	"gitoa.ru/go-4devs/config"
+	"gitoa.ru/go-4devs/config/processor/json"
+	"gitoa.ru/go-4devs/config/test/require"
+	"gitoa.ru/go-4devs/config/value"
+)
+
+func TestJson(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	val, err := json.Json(ctx, value.String("42"))
+	require.NoError(t, err)
+
+	var res int
+	require.NoError(t, val.Unmarshal(&res))
+	require.Equal(t, 42, res)
+
+	sval, serr := json.Json(ctx, value.String("\"test data\""))
+	require.NoError(t, serr)
+
+	var sres string
+	require.NoError(t, sval.Unmarshal(&sres))
+	require.Equal(t, "test data", sres)
+
+	slval, slerr := json.Json(ctx, value.String("[\"test\",\"test2 data\",\"test3\"]"))
+	require.NoError(t, slerr)
+
+	var slres []string
+	require.NoError(t, slval.Unmarshal(&slres))
+	require.Equal(t, []string{"test", "test2 data", "test3"}, slres)
+}
+
+func TestJson_invalidValue(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	val, err := json.Json(ctx, value.New("42"))
+	require.NoError(t, err)
+
+	var data string
+	require.ErrorIs(t, val.Unmarshal(&data), config.ErrInvalidValue)
+}