public void ParseNonwordCharInVariable()
        {
            // Arrange
            var comparer = new TokenEqualityComparer();

            // Act
            var tokens = Parse("a $b c$d$");

            // Assert
            Assert.Equal(
                new[] {
                new Token(TokenCategory.Text, "a $b c"),
                new Token(TokenCategory.Variable, "d"),
            },
                tokens,
                comparer);
        }
        public void ParseVariables()
        {
            // Arrange
            var comparer = new TokenEqualityComparer();

            // Act
            var tokens = Parse("a $b$$c$");

            // Assert
            Assert.Equal(
                new[] {
                new Token(TokenCategory.Text, "a "),
                new Token(TokenCategory.Variable, "b"),
                new Token(TokenCategory.Variable, "c")
            },
                tokens,
                comparer);
        }