mathml/test_tex.tex

\documentclass{article}
\usepackage{luamml}
\usepackage{amsmath,array}

\usepackage{unicode-math}
%% Uncomment the following lines when used without unicode-math
% \RegisterFamilyMapping\symsymbols{oms}
% \RegisterFamilyMapping\symletters{oml}
% \RegisterFamilyMapping\symlargesymbols{omx}

\ExplSyntaxOn
\tracingmathml=2
\pdfvariable compresslevel=0
\cs_new_protected:Npn \ShowMathMLObj {
  \message { \luamml_get_last_mathml_stream:e{}~0~R }
}
\ExplSyntaxOff

\begin{document}
\[
  \begin{pmatrix}
    1 & 0 & 0 \\
    0 & 1 & 0 \\
    0 & 0 & 1
  \end{pmatrix}
  =
  \begin{cases}
    1 & $if $a=b\\
    2 & $else$
  \end{cases}
\]
\ShowMathMLObj
\[
  x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}.
\]
\[
  \sum_a\underline c\dot bc'
\]

\begin{align}
  abc&=def & e^{\mathrm{i}\pi}&=-1\\
  \Big(1+2&=3\Big)\\
  5
\end{align}

Es gilt $\sin(x)-\sin(x+2\pi)=0$.
\end{document}