public void AllowChars_String()
        {
            // Arrange
            var filter = new CodePointFilter();

            // Act
            var retVal = filter.AllowChars("\u0100\u0102");

            // Assert
            Assert.Same(filter, retVal); // returns 'this' instance
            Assert.True(filter.IsCharacterAllowed('\u0100'));
            Assert.False(filter.IsCharacterAllowed('\u0101'));
            Assert.True(filter.IsCharacterAllowed('\u0102'));
            Assert.False(filter.IsCharacterAllowed('\u0103'));
        }
        public void AllowChars_String()
        {
            // Arrange
            var filter = new CodePointFilter();

            // Act
            var retVal = filter.AllowChars("\u0100\u0102");

            // Assert
            Assert.Same(filter, retVal); // returns 'this' instance
            Assert.True(filter.IsCharacterAllowed('\u0100'));
            Assert.False(filter.IsCharacterAllowed('\u0101'));
            Assert.True(filter.IsCharacterAllowed('\u0102'));
            Assert.False(filter.IsCharacterAllowed('\u0103'));
        }