A simple library that facilitates runtime checks of code and allows to define preconditions and invariants within a method.
Its main purpose is to leverage the precondition checks that appear in almost all methods, through a clean interface that accentuates intention and eliminates confusion.
public void AddUser(User user)
{
Guard.NotNull(user, nameof(user), "optional custom error message"); // throws ArgumentNullException
// OR use an explicit Exception
var invalidOperationException = new InvalidOperationException("custom message");
Guard.NotNull(user, invalidOperationException);
...
}
public void GetUserByName(string name)
{
Guard.NotNullOrWhitespace(name, nameof(name), "optional custom error message"); // throws ArgumentException
// OR use an explicit Exception
var invalidOperationException = new InvalidOperationException("custom message");
Guard.NotNullOrWhitespace(userName, invalidOperationException);
...
}
public void GetUsers(int pageSize)
{
Guard.NotGreaterThan(pageSize, _maxPageSize, nameof(pageSize), "optional custom error message"); // throws ArgumentOutOfRangeException
// OR use an explicit Exception
var invalidOperationException = new InvalidOperationException("custom message");
Guard.NotGreaterThan(pageSize, _maxPageSize, invalidOperationException);
...
}
public void UpdateEmailAddress(int userId, string newEmailAddress)
{
Guard.For(() => userId < 0, new ArgumentException(nameof(userId)));
Guard.For(() => Regex.IsMatch(newEmailAddress, _emailRegexPattern), new ArgumentException(nameof(newEmailAddress)));
...
}
The Guard class can be used by installing Guard.NET nuget package available here.
Install-Package Guard.NET
The package has no external dependencies.
