public void GetAllAccountClasses_ShouldReturnAllValidValues_UnderAllConditions()
{
// Arrange & Act
AccountClass[] output = CUT.GetAllAccountClasses().ToArray();
// Assert
output.ShouldNotBeNull();
output.ShouldNotBeEmpty();
output.ShouldContain(AccountClass.Residential);
output.ShouldContain(AccountClass.SmallCommercial);
output.ShouldContain(AccountClass.LargeCommercial);
}
