public static void Ctor_String_Int_Int_Int(string value, int startIndex, int length)
{
var builder = new StringBuilder(value, startIndex, length, 42);
string expected = value?.Substring(startIndex, length) ?? "";
Assert.Equal(expected, builder.ToString());
Assert.Equal(length, builder.Length);
Assert.Equal(expected.Length, builder.Length);
Assert.True(builder.Capacity >= 42);
}