Equalsメソッドのテストを補助するやつ

gistfile1.cs

namespace Program
{
    internal static class TestUtils
    {
        public static void CheckEqualsMethod<T>(params Expression<Func<T, string>>[] fieldAccessLambda)
            where T : new()
        {
            foreach (var lambda in fieldAccessLambda)
            {
                var assign = ConvertFieldAccessToAssign(lambda);
                var fieldName = ((MemberExpression)lambda.Body).Member.Name;

                var testObj1 = new T();
                var testObj2 = new T();

                assign(testObj1, "aaa");
                assign(testObj2, "aaa");
                Assert.True(testObj1.Equals(testObj2), fieldName);

                assign(testObj1, "aaa");
                assign(testObj2, "bbb");
                Assert.False(testObj1.Equals(testObj2), fieldName);
                Assert.False(testObj2.Equals(testObj1), fieldName);

                assign(testObj1, null);
                assign(testObj2, null);
                Assert.True(testObj1.Equals(testObj2), fieldName);

                assign(testObj1, null);
                assign(testObj2, "aaa");
                Assert.False(testObj1.Equals(testObj2), fieldName);
                Assert.False(testObj2.Equals(testObj1), fieldName);
            }
        }

        /// <summary>
        ///  x => x.Hoge の式木を (x, y) => x.Hoge = y の形に変形します
        /// </summary>
        private static Action<Tin, Tout> ConvertFieldAccessToAssign<Tin, Tout>(Expression<Func<Tin, Tout>> fieldAccessLambda)
        {
            var paramTestObject = fieldAccessLambda.Parameters.Single();
            var paramAssignValue = Expression.Parameter(typeof(Tout), "y");

            var fieldAssignLambda = Expression.Lambda<Action<Tin, Tout>>(
                Expression.Assign((MemberExpression)fieldAccessLambda.Body, paramAssignValue),
                paramTestObject, paramAssignValue);

            return fieldAssignLambda.Compile();
        }
    }
}