public IEnumerable <string> TextElement([PexAssumeNotNull] string input)
{
// arrange
int[] compiningCharacters = StringInfo.ParseCombiningCharacters(input);
// act
IEnumerable <string> result = CommonStringExtensions.TextElements(input);
// assert
PexAssert.IsNotNull(result);
PexAssert.AreEqual(compiningCharacters.Count(), result.Count());
return(result);
}