Mocking the RolesInRoles Provider

[Fact]
public void HowToMockRolesInRolesProvider()
{
  // create and configure roles-in-roles provider mock
  var role = Sitecore.Security.Accounts.Role.FromName(@"sitecore/Editors");
  var user = Sitecore.Security.Accounts.User.FromName(@"sitecore/John", false);

  var provider =
    Substitute.For<Sitecore.Security.Accounts.RolesInRolesProvider>();
  provider.IsUserInRole(user, role, true).Returns(true);

  // switch the roles-in-roles provider so the mocked version is used
  using (new Sitecore.FakeDb.Security.Accounts.RolesInRolesSwitcher(provider))
  {
    Xunit.Assert.True(user.IsInRole(role));
  }
}