[MM-36472] Fix inconsistencies in Roles columns (#18390)

* Fix inconsistencies in Roles columns

* Add new migrations

model/session_test.go

@@ -5,12 +5,74 @@ package model
 
 import (
 	"strconv"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
+func TestSessionIsValid(t *testing.T) {
+	tcs := []struct {
+		name          string
+		input         Session
+		expectedError string
+	}{
+		{
+			"Invalid Id",
+			Session{},
+			"model.session.is_valid.id.app_error",
+		},
+		{
+			"Invalid UserId",
+			Session{
+				Id: NewId(),
+			},
+			"model.session.is_valid.user_id.app_error",
+		},
+		{
+			"Invalid CreateAt",
+			Session{
+				Id:     NewId(),
+				UserId: NewId(),
+			},
+			"model.session.is_valid.create_at.app_error",
+		},
+		{
+			"Invalid Roles",
+			Session{
+				Id:       NewId(),
+				UserId:   NewId(),
+				CreateAt: 1000,
+				Roles:    strings.Repeat("a", UserRolesMaxLength+1),
+			},
+			"model.session.is_valid.roles_limit.app_error",
+		},
+		{
+			"Valid",
+			Session{
+				Id:       NewId(),
+				UserId:   NewId(),
+				CreateAt: 1000,
+				Roles:    strings.Repeat("a", UserRolesMaxLength),
+			},
+			"",
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			err := tc.input.IsValid()
+			if tc.expectedError != "" {
+				require.NotNil(t, err)
+				require.Equal(t, tc.expectedError, err.Id)
+			} else {
+				require.Nil(t, err)
+			}
+		})
+	}
+}
+
 func TestSessionDeepCopy(t *testing.T) {
 	sessionId := NewId()
 	userId := NewId()