How to inject arguments into forest as tree

Question

From the documentation, there is something called action character=@ to unfold macros. But if i try to use it with this code:

\newcommand{\hierarchy}[1]
{

\bracketset{action character=@}

\begin{forest}
forked edges,
for tree={
    font=\sffamily\bfseries,
    line width=1pt,
    draw=linecol,
    ellip=5,
    align=center,
    grow'=0,
    edge+={color=linecol, line width=1pt, rounded corners=5pt, -Stealth},
    drop shadow,
    anchor=parent,
    l sep'+=5pt,
},
where={isodd(n_children())}{%
    for n/.wrap pgfmath arg={{#1}{calign with current edge}}{int((n_children()+1)/2)}
}{},
where level=2{tier=second}{}
    @{#1}
\end{forest}
}

}

there is a error which says:

Package forest error: nodewalk stepped to the invalid node

I guess it has something to do with the second #1 expression in

where={isodd(n_children())}{%
     for n/.wrap pgfmath arg={{#1}{calign with current edge}}
{int((n_children()+1)/2)}
}{},

Any suggestions how to handle this?

Here is an complete example document:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[edges]{forest}
\usetikzlibrary{arrows.meta,shapes.geometric,shadows}
\title{Tests}


\date{October 2017}


\tikzset{ellip/.append style={rounded rectangle, inner color=blue!30, outer color=blue!40}}

\newcommand{\hierarchy}[1]
{

{\footnotesize

\bracketset{action character=@}

\begin{forest}
    forked edges,
    for tree={
        font=\sffamily\bfseries,
        line width=1pt,
        draw=black,
        ellip=5,
        align=center,
        grow'=0,
        edge+={line width=1pt, rounded corners=5pt, -Stealth},
        drop shadow,
        anchor=parent,
        l sep'+=5pt,
    },
    where={isodd(n_children())}{%
        for n/.wrap pgfmath arg={{#1}{calign with current edge}}{int((n_children()+1)/2)}
    }{},
    where level=2{tier=second}{}
    @{#1}
\end{forest}
}
}

\begin{document}

\hierarchy{
 [Test1[Test2][Test3[...]]]
}

\end{document}