public void FontListener_FillRelativeFont_FillsRelativeFontOptionalValues(string input, RelativeFont expected)
{
// Given.
var font = new AutoFont();
var parser = CreateParser(input);
var tree = parser.font();
WalkParseTree(tree);
// When.
TestSubject.FillRelativeFont(font, tree.relativeFont());
// Then.
font.Should().BeEquivalentTo(expected, opt => opt
.Excluding(x => x.Type));
}