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using System;
using System.Reflection;
using NUnit.Framework;

namespace XenAdminTests.UnitTests.UnitTestHelper
{
    public class VerifyStaticMethodReturn : IUnitTestVerifier
    {
        private readonly Type typeTovalidate;

        public VerifyStaticMethodReturn(Type typeTovalidate)
        {
            this.typeTovalidate = typeTovalidate;
        }

        /// <summary>
        /// Use this class to go through a class with the constructed type and 
        /// verify there are methods that return the expected type and the
        /// return value is not null
        /// </summary>
        /// <param name="returnTypeForMethod">Type that the static method will check for as a return type</param>
        public void Verify( object returnTypeForMethod )
        {
            Type returnType = returnTypeForMethod as Type;
            MethodInfo[] methods = typeTovalidate.GetMethods();
            
            Assert.AreNotEqual(0, methods.Length, "No methods found returning " + returnType );

            int staticMethodCount = 0;
            foreach (MethodInfo methodInfo in methods)
            {
                if (methodInfo.ReturnType == returnType && methodInfo.IsStatic)
                {
                    Assert.IsNotNull(methodInfo.Invoke(null, null), "Null value returned for " + methodInfo.Name);
                    staticMethodCount++;
                }
            }

            Assert.AreNotEqual(0, staticMethodCount, "Static method call count should not be zero");
        }
    }
}
