newcommand with argument produces unwanted extra space within tikzpicture

Question

I am creating some pictures I want to use within nodes. When I use a \newcommand with an argument, extra space is added and I can't get rid of it.

\documentclass{article}
\usepackage{tikz}
\begin{document}

\newcommand{\foo}[1][3]{
\begin{tikzpicture}
    \foreach \x in {0,1,...,#1}
        \filldraw (\x,0) circle (0.2cm);
\end{tikzpicture}
}

\newcommand{\test}{
\begin{tikzpicture}
    \foreach \x in {0,1,...,3}
        \filldraw (\x,0) circle (0.2cm);
\end{tikzpicture}
}

\begin{tikzpicture}
    \node at(0,0)    [draw, rectangle, inner sep=0] {\foo};
    \node at(0,-0.5) [draw, rectangle, inner sep=0] {\test};
\end{tikzpicture}
\end{document}

Answer 1

Remove spurious blank spaces:

\newcommand{\foo}[1][3]{%
\begin{tikzpicture}
    \foreach \x in {0,1,...,#1}
        \filldraw (\x,0) circle (0.2cm);
\end{tikzpicture}%
}

\newcommand{\test}{%
\begin{tikzpicture}
    \foreach \x in {0,1,...,3}
        \filldraw (\x,0) circle (0.2cm);
\end{tikzpicture}%
}