miscellaneous_test.tex

%! TEX program = lualatex
\documentclass[12pt]{article}
\usepackage[paper=a4paper,margin=0.6cm]{geometry}
\usepackage{luacode}
\usepackage{miscellaneous}
\begin{document}

\ExplSyntaxOn
% some assertions~
\str_if_startswith:nnTF {abc} {a}
{
}
{
	\msg_error:nn {module} {ERROR}
}

\str_if_startswith:nnTF {abc} {b}
{
	\msg_error:nn {module} {ERROR}
}
{
}
\ExplSyntaxOff
all okay

\end{document}