private TestValue CreateDefaultTestValueBabyDiaper(
     TestValueType testValueType,
     TestTypeBabyDiaper
     testTypeBabyDiaper
     )
 => new TestValue
 {
     ArticleTestType            = ArticleType.BabyDiaper,
     CreatedDateTime            = DateTime.Now,
     CreatedPerson              = "system",
     LastEditedDateTime         = DateTime.Now,
     TestValueType              = testValueType,
     LastEditedPerson           = "system",
     DayInYearOfArticleCreation = DateTime.Now.DayOfYear,
     BabyDiaperTestValue        = new BabyDiaperTestValue
     {
         TestType          = testTypeBabyDiaper,
         RetentionRw       = RwType.Ok,
         Rewet140Rw        = RwType.Ok,
         Rewet210Rw        = RwType.Ok,
         PenetrationRwType = RwType.Ok
     }
 };
        /// <summary>
        ///     Gets the BabyDiaperTestValue out of a list of testvalues for the correct <see cref="TestTypeBabyDiaper" /> and
        ///     <see cref="TestValueType" />
        ///     One must exists and only one.
        /// </summary>
        /// <param name="testValues">the test values containing the wanted item</param>
        /// <param name="testTypeBabyDiaper">the type of the baby diaper. <see cref="TestTypeBabyDiaper" /></param>
        /// <param name="testValueType">the value type of the baby diaper. <see cref="TestValueType" /></param>
        /// <returns></returns>
        public BabyDiaperTestValue GetBabyDiaperTestValueForType(IEnumerable <TestValue> testValues, TestTypeBabyDiaper testTypeBabyDiaper, TestValueType testValueType)
        {
            var values = testValues.ToList()
                         .Where(
                x => (x.TestValueType == testValueType) && (x.BabyDiaperTestValue.TestType == testTypeBabyDiaper))
                         .ToList();
            var item = ValidateTestValueOnlyExactlyOneHasToExist(values, testTypeBabyDiaper.ToString(), testValueType.ToString());

            return(item.BabyDiaperTestValue);
        }