Set Theorem counter as subsection number + 0.1?

Question

How to adjust counters for so that theorem is subsection+0.1 and the subsection number adjusts itself after the theorem. For example in the code below the output produces 1.1 subsection followed by the Theorem 1.1 (I want this to be Theorem 1.2) this is followed by 1.2 Another Subsection (I want this to 1.3).

I have tried using \addcounter and \setcounter but it does not produce the desired result.

\documentclass{article}
\usepackage{amsthm}

\newtheorem{theorem}{Theorem}[section]


\begin{document}

\section{Test Section} some text
\subsection{subsection} blah
\begin{theorem}
    How to set the theorem counter to 1.2 instead of 1.1 as in the output.
\end{theorem}
\subsection{Another subsection} How to set this counter to 1.3


\end{document}

Answer 1

You can set the theorem counter to be an alias (or duplicate) for the subsection counter using the methods described in Slave duplicate counter.

\documentclass{article}

\usepackage{amsthm}

\newtheorem{theorem}{Theorem}[section]

\makeatletter
\newcommand*{\dupcntr}[2]{%
  \expandafter\let\csname c@#1\expandafter\endcsname\csname c@#2\endcsname
}
\makeatother
\dupcntr{theorem}{subsection}

\begin{document}

\section{Test Section} some text

\subsection{subsection} blah
\begin{theorem}
How to set the theorem counter to 1.2 instead of 1.1.
\end{theorem}

\subsection{Another subsection} How to set this counter to 1.3

\end{document}