Snippets for 2009 blog post "Code Contracts"

CodeContracts1.cs

/// <summary>
/// Search for a collection of customers, given a set of criteria.
/// </summary>
/// <param name="queryCriteria" />Query Object defining the search criteria.</param>
/// <returns>Collection of customers matching the specified criteria.</returns>
/// <exception cref="System.ArgumentNullException">Where queryCriteria is null</exception>
/// <exception cref="System.ArgumentException">Where no query criteria have been set (we do not permit searching for all customers)</exception>
public static CustomerCollection Find(CustomerQuery queryCriteria)
{
    #region Validate parameters

    // Guard clause 1 - null queryCriteria - throw exception
    if ( queryCriteria == null ) throw new ArgumentNullException( "queryCriteria" );
    // Guard clause 2 - no query criteria specified - throw exception
    if ( !queryCriteria.IsUsed( SourceSystem.All ) ) throw new ArgumentException( ExceptionMessages.BusinessLogic_CustomerRepository_Find_NoCriteriaSpecified, "queryCriteria" );
    
    #endregion
    // More stuff here to return customers
}

CodeContracts2.cs

// Guard clause 1 - null queryCriteria
Contract.Requires( queryCriteria!=null );

// Guard clause 2 - no query criteria specified
Contract.Requires( queryCriteria.IsUsed( SourceSystem.All ), ExceptionMessages.BusinessLogic_CustomerRepository_Find_NoCriteriaSpecified);