public void AddElementToArray()
{
// Arrange
var document = new XmlDocument(@"<xml>
<a>
<x>1</x>
</a>
<b>2</b>
<c>3</c>
<d />
</xml>");
// Act
document.AddElementToArray(new[] { "xml", "d" }, "<val>1</val>");
document.AddElementToArray(new[] { "xml", "d" }, "<val>2</val>");
document.AddElementToArray(new[] { "xml", "f" }, "<x>1</x>");
var result = document.ToString();
// Assert
Assert.Equal(@"<xml>
<a>
<x>1</x>
</a>
<b>2</b>
<c>3</c>
<d>
<val>1</val>
<val>2</val>
</d>
<f>
<x>1</x>
</f>
</xml>", result, ignoreCase: true, ignoreLineEndingDifferences: true, ignoreWhiteSpaceDifferences: true);
}