\DocumentMetadata{}
\input regression-test.tex
\documentclass{ltx-talk}
\usepackage{ltxtalk-theme-minimal}

\title[T]{Plain block glue}
\author[A]{A}
\date{}

\begin{document}
\ExplSyntaxOn
\skip_new:N \l__ltxtalk_test_medskip_skip
\skip_set_eq:NN \l__ltxtalk_test_medskip_skip \medskipamount
\int_new:N \l__ltxtalk_test_medskip_int
\cs_new_eq:NN \__ltxtalk_test_medskip: \medskip
\cs_set_protected:Npn \medskip
  {
    \int_gincr:N \l__ltxtalk_test_medskip_int
    \int_compare:nNnTF { \l__ltxtalk_test_medskip_int } < { 3 }
      {
        \skip_if_eq:nnTF { \medskipamount } { 0pt }
          { \TYPE { block-header-medskip:removed } }
          { \TYPE { block-header-medskip:FAILED } }
      }
      {
        \int_compare:nNnT { \l__ltxtalk_test_medskip_int } = { 3 }
          {
            \exp_args:NVV \skip_if_eq:nnTF
              \medskipamount \l__ltxtalk_test_medskip_skip
              { \TYPE { block-body-medskip:preserved } }
              { \TYPE { block-body-medskip:FAILED } }
          }
      }
    \__ltxtalk_test_medskip:
  }
\START
\begin{frame}
  \frametitle{Plain block glue}
  \begin{block}{Card title}
    \skip_set:Nn \l_tmpa_skip { \tex_lastskip:D }
    \exp_args:NVV \skip_if_eq:nnTF \l_tmpa_skip \c_zero_skip
      { \TYPE { block-body-leading-glue:removed } }
      { \TYPE { block-body-leading-glue:FAILED } }
    \medskip
    Card body.
  \end{block}
\end{frame}
\ExplSyntaxOff
\END
\end{document}