using System.Collections.Generic;
using NUnit.Framework;

namespace System
{
    /// <summary>
    /// A set of reusable tests for testing types that implement 
    /// <see cref="IServiceProvider"/>.
    /// </summary>
    public abstract class ServiceProviderTests
    {
        [Test, Description("Ensures the IServiceProvider.GetService(Type) method " + 
            "returns a non-null service that is of the proper type " +
            "(ICollection<Int32> in this case), and is equal to " +
            "ServiceProviderTests.ExpectedService.")]
        public void GetServiceTest()
        {
            IServiceProvider serviceProvider = CreateServiceProvider();
            
            Type expectedType = typeof (ICollection<Int32>);
            object service = serviceProvider.GetService(expectedType);

            Assert.NotNull(service);
            Assert.IsInstanceOf(expectedType, service);
            Assert.AreEqual(ExpectedService, service);
        }

        /// <summary>
        /// Creates the <see cref="IServiceProvider"/> to test. This method 
        /// should always create a new instance. The <see cref="IServiceProvider"/>
        /// must contain a service of type <see cref="ICollection{T}"/> that
        /// is not null and equal to <see cref="ServiceProviderTests.ExpectedService"/>.
        /// </summary>
        /// <returns>The <see cref="IServiceProvider"/> instance to test.</returns>
        protected abstract IServiceProvider CreateServiceProvider();

        /// <summary>
        /// The service that is to be contained within the 
        /// <see cref="IServiceProvider"/> returned by 
        /// <see cref="CreateServiceProvider()"/>.
        /// </summary>
        protected abstract ICollection<Int32> ExpectedService { get; }
    }
}