[#36] Add attribute parser

Attribute parser converts strings of attribute chain into
one-dimension array of NodeInfo attributes, that used
in network map.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/util/attributes/parser_test.go

@@ -0,0 +1,60 @@
+package attributes_test
+
+import (
+	"testing"
+
+	"github.com/nspcc-dev/neofs-node/pkg/util/attributes"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseV2Attributes(t *testing.T) {
+	t.Run("empty", func(t *testing.T) {
+		attrs, err := attributes.ParseV2Attributes(nil, nil)
+		require.NoError(t, err)
+		require.Len(t, attrs, 0)
+	})
+
+	t.Run("non unique bucket keys", func(t *testing.T) {
+		good := []string{
+			"StorageType:HDD/RPM:7200",
+			"StorageType:HDD/SMR:True",
+		}
+		_, err := attributes.ParseV2Attributes(good, nil)
+		require.NoError(t, err)
+
+		bad := append(good, "StorageType:SSD/Cell:QLC")
+		_, err = attributes.ParseV2Attributes(bad, nil)
+		require.Error(t, err)
+
+	})
+
+	t.Run("malformed", func(t *testing.T) {
+		_, err := attributes.ParseV2Attributes([]string{"..."}, nil)
+		require.Error(t, err)
+
+		_, err = attributes.ParseV2Attributes([]string{"a:b", ""}, nil)
+		require.Error(t, err)
+
+		_, err = attributes.ParseV2Attributes([]string{"//"}, nil)
+		require.Error(t, err)
+	})
+
+	t.Run("unexpected", func(t *testing.T) {
+		unexpectedBucket := []string{
+			"Location:Europe/City:Moscow",
+			"Price:100",
+		}
+		_, err := attributes.ParseV2Attributes(unexpectedBucket, []string{"Price"})
+		require.Error(t, err)
+	})
+
+	t.Run("correct", func(t *testing.T) {
+		from := []string{
+			"/Location:Europe/Country:Sweden/City:Stockholm",
+			"/StorageType:HDD/RPM:7200",
+		}
+		attrs, err := attributes.ParseV2Attributes(from, nil)
+		require.NoError(t, err)
+		require.Len(t, attrs, 5)
+	})
+}