how to properly test an abstract class

Question

I\'m currently in the process of creating a unit test for an abstract class, called Component. VS2008 compiled my program no problems so I was able to create a

Answer 1

This is how I do it. With a inner-nested-class on the UnitTest class.

namespace MyCompany.MyProject.UnitTests
{
    using System;
    using System.Collections.Generic;
    using System.Text;
    using System.Threading.Tasks;
    using Microsoft.VisualStudio.TestTools.UnitTesting;
    using FluentAssertions;

    [TestClass]
    [System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
    public class MyAbstractClassTests
    {
        [TestMethod]
        public void ConstructorILoggerFactoryIsNullTest()
        {
            Action a = () => new MyUnitTestConcreteClass(null);
            a.Should().Throw().WithMessage(MyAbstractClass.ErrorMessageILoggerFactoryIsNull);

        }

        [TestMethod]
        public void GetABooleanIsTrueTest()
        {
            /* here is more likely what you want to test..an implemented method on the abstract class */
            Mock iloggerFactoryMock = this.GetDefaultILoggerFactoryMock();
            MyUnitTestConcreteClass testItem = new MyUnitTestConcreteClass(iloggerFactoryMock.Object);
            Assert.IsTrue(testItem.GetABoolean());
        }   

        [TestMethod]
        public void GetSomeIntsIsNotNullTest()
        {
            /* you may not want to test the abstract methods, but you can */
            Mock iloggerFactoryMock = this.GetDefaultILoggerFactoryMock();
            MyUnitTestConcreteClass testItem = new MyUnitTestConcreteClass(iloggerFactoryMock.Object);
            Assert.IsNotNull(testItem.GetSomeInts());
        }       


        private Mock GetDefaultILoggerFactoryMock()
        {
            Mock returnMock = new Mock(MockBehavior.Strict);
            ////returnMock.Setup(x => x.SomeBooleanMethod()).Returns(true);
            return returnMock;
        }       



        internal class MyUnitTestConcreteClass : MyAbstractClass
        {
            internal MyUnitTestConcreteClass(ILoggerFactory loggerFactory) : base(loggerFactory)
            {
            }

            public override ICollection GetSomeInts()
            {
                return new List { 111, 222, 333 };
            }
        }
    }
}

and the "real" abstract class below

public abstract class MyAbstractClass : where T : struct
{

    public const string ErrorMessageILoggerFactoryIsNull = "ILoggerFactory is null";

    public WhiteListStepBodyAsyncBase(ILoggerFactory loggerFactory)
    {
        if (null == loggerFactory)
        {
            throw new ArgumentNullException(ErrorMessageILoggerFactoryIsNull, (Exception)null);
        }

    }           

    public bool GetABoolean()
    {
          /* note , this is important factor (sometimes), here this implemented method DEPENDS on an abstract method , and why I have the code "return new List { 111, 222, 333 };" above .. see the connection ?? */
                    return this.GetSomeInts().Count > 0;
    }

    public abstract ICollection GetSomeInts();


}

This question is older, but the principals are the same.

Here are my VS2019, year 2020 .. package imports.

  
    
      all
      runtime; build; native; contentfiles; analyzers; buildtransitive