native: introduce Stringer for noderoles types

And rename roles.go to role.go to match the role_string.go and the
existing naming pattern for enums.

Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>

pkg/core/native/noderoles/role.go

@@ -0,0 +1,35 @@
+package noderoles
+
+//go:generate stringer -type=Role
+
+// Role represents the type of the participant.
+type Role byte
+
+// Role enumeration.
+const (
+	_ Role = 1 << iota
+	_
+	StateValidator
+	Oracle
+	NeoFSAlphabet
+	P2PNotary
+	// last denotes the end of roles enum. Consider adding new roles before the last.
+	last
+)
+
+// roles is a map of valid Role string representation to its type.
+var roles map[string]Role
+
+func init() {
+	roles = make(map[string]Role)
+	for i := StateValidator; i < last; i = i << 1 {
+		roles[i.String()] = i
+	}
+}
+
+// FromString returns a node role parsed from its string representation and a
+// boolean value denoting whether the conversion was OK and the role exists.
+func FromString(s string) (Role, bool) {
+	r, ok := roles[s]
+	return r, ok
+}

pkg/core/native/noderoles/role_string.go

@@ -0,0 +1,41 @@
+// Code generated by "stringer -type=Role"; DO NOT EDIT.
+
+package noderoles
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[StateValidator-4]
+	_ = x[Oracle-8]
+	_ = x[NeoFSAlphabet-16]
+	_ = x[P2PNotary-32]
+	_ = x[last-64]
+}
+
+const (
+	_Role_name_0 = "StateValidator"
+	_Role_name_1 = "Oracle"
+	_Role_name_2 = "NeoFSAlphabet"
+	_Role_name_3 = "P2PNotary"
+	_Role_name_4 = "last"
+)
+
+func (i Role) String() string {
+	switch {
+	case i == 4:
+		return _Role_name_0
+	case i == 8:
+		return _Role_name_1
+	case i == 16:
+		return _Role_name_2
+	case i == 32:
+		return _Role_name_3
+	case i == 64:
+		return _Role_name_4
+	default:
+		return "Role(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+}

pkg/core/native/noderoles/role_test.go

@@ -0,0 +1,27 @@
+package noderoles
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFromString(t *testing.T) {
+	valid := map[string]Role{
+		"StateValidator": StateValidator,
+		"Oracle":         Oracle,
+		"NeoFSAlphabet":  NeoFSAlphabet,
+		"P2PNotary":      P2PNotary,
+	}
+	for s, expected := range valid {
+		actual, ok := FromString(s)
+		require.True(t, ok)
+		require.Equal(t, expected, actual)
+	}
+
+	invalid := []string{"last", "InvalidRole"}
+	for _, s := range invalid {
+		_, ok := FromString(s)
+		require.False(t, ok)
+	}
+}

pkg/core/native/noderoles/roles.go

@@ -1,12 +0,0 @@
-package noderoles
-
-// Role represents the type of the participant.
-type Role byte
-
-// Role enumeration.
-const (
-	StateValidator Role = 4
-	Oracle         Role = 8
-	NeoFSAlphabet  Role = 16
-	P2PNotary      Role = 32
-)