Coordinator Role: json marshaling as string

coordinator/role/role.go

@@ -1,5 +1,10 @@
 package role
 
+import (
+	"encoding/json"
+	"strings"
+)
+
 //go:generate stringer -type=Role
 
 // Role is a peer's role.
@@ -10,3 +15,26 @@ const (
 	Coordinator
 	Node
 )
+
+// MarshalJSON marshals the Role to JSON string.
+func (r Role) MarshalJSON() ([]byte, error) {
+	return json.Marshal(r.String())
+}
+
+// UnmarshalJSON unmarshals the Role from JSON string.
+func (r *Role) UnmarshalJSON(b []byte) error {
+	var roleString string
+	if err := json.Unmarshal(b, &roleString); err != nil {
+		return err
+	}
+	switch strings.ToLower(roleString) {
+	case "coordinator":
+		*r = Coordinator
+
+	case "node":
+		*r = Node
+	default:
+		*r = Unknown
+	}
+	return nil
+}

coordinator/role/role_test.go

@@ -0,0 +1,96 @@
+package role
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestMarshal(t *testing.T) {
+	testCases := map[string]struct {
+		role         Role
+		jsonExpected string
+		errExpected  bool
+	}{
+		"coordinator role": {
+			role:         Coordinator,
+			jsonExpected: `"Coordinator"`,
+		},
+		"node role": {
+			role:         Node,
+			jsonExpected: `"Node"`,
+		},
+		"unknown role": {
+			role:         Unknown,
+			jsonExpected: `"Unknown"`,
+		},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			assert := assert.New(t)
+			require := require.New(t)
+
+			jsonRole, err := tc.role.MarshalJSON()
+			if tc.errExpected {
+				assert.Error(err)
+				return
+			}
+
+			require.NoError(err)
+			assert.Equal(tc.jsonExpected, string(jsonRole))
+		})
+	}
+}
+
+func TestUnmarshal(t *testing.T) {
+	testCases := map[string]struct {
+		json         string
+		expectedRole Role
+		errExpected  bool
+	}{
+		"Coordinator can be unmarshaled": {
+			json:         `"Coordinator"`,
+			expectedRole: Coordinator,
+		},
+		"lowercase coordinator can be unmarshaled": {
+			json:         `"coordinator"`,
+			expectedRole: Coordinator,
+		},
+		"Node can be unmarshaled": {
+			json:         `"Node"`,
+			expectedRole: Node,
+		},
+		"lowercase node can be unmarshaled": {
+			json:         `"node"`,
+			expectedRole: Node,
+		},
+		"other strings unmarshal to the unknown role": {
+			json:         `"anything"`,
+			expectedRole: Unknown,
+		},
+		"invalid json fails": {
+			json:        `"unterminated string literal`,
+			errExpected: true,
+		},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			assert := assert.New(t)
+			require := require.New(t)
+
+			var role Role
+			err := role.UnmarshalJSON([]byte(tc.json))
+
+			if tc.errExpected {
+				assert.Error(err)
+				return
+			}
+
+			require.NoError(err)
+			assert.Equal(tc.expectedRole, role)
+		})
+	}
+}